C S b. Gld>'P 96/9 »▼ U.S. DEPARTMENT OF COMMERCE Robert A.Mosbacher, Secretary W % National Oceanic and Atmospheric Administration c John A. Knauss, Under Secretary for Oceans and Atmosphere/Administrator Environmental Research Laboratories Joseph O. Fletcher, Director Enviromiieiital Research Laboratories Publicetion Abstracts FY 1991 PHMNSVLVAN^ MftR3 0A3K Offlber 1991 Boulder, Colorado FOREWORD As the research arm of the National Oceanic and Atmospheric Administration (NOAA), the Environmental Research Laboratories (ERL) support the present responsibilities and the development of future services of NOAA. Programs include investigation of ocean processes and their interactions with the atmosphere; studies of the ocean environment as it is affected by waste disposal and development of energy and food resources; fundamental studies of the upper atmosphere and space environments; atmosphere and ocean research on weather and climate change; research on severe local storms, hurricanes, and tsunamis; studies of cloud processes; research on the environmental effects of regional and global pollution; and development of equipment, instruments, systems, and facilities for these programs. A principal measure of the success of a research laboratory is its output of scientific and technical papers and reports. The listings (including abstracts when available) in the following pages are an index of such ERL output for the period October 1, 1990, through September 30, 1991. This document includes all known articles published in journals for FY 1991 and those reports published within the official series of the Laboratories, as well as conference proceedings and other reports. It also includes publications by ERL- University cooperative institutes and by contractors funded by ERL. Joseph O. Fletcher, Director Environmental Research Laboratories Boulder, Colorado HI A GUIDE FOR USERS Abstracts for this volume were submitted print ready by each Laboratory. If no abstract accompanied the original publication, the words "No abstract" follow the bibliographic entry. Sections are arranged alphabetically by Laboratory. Some Laboratories have included an addendum listing publications inadvertently omitted from the FY 1990 volume. Entries within the Laboratory sections are arranged alphabetically by author. ERL authors' names are typed in all capital letters. An author index starts on p. 201. A guide for using the index is on p. 200. Availability of Publications Papers published in scientific and technical journals are available through the journals. NOAA Technical Reports, Technical Memorandums, and Data Reports are available from National Technical Information Service (NTIS) U.S. Department of Commerce 5285 Port Royal Road Springfield, VA 22161 (703) 487-4600 FTS: Access code + 202 + 487-4600 The NTIS order number (if available at the time of publication of this document) is in parentheses following the report number in the bibliographic entry. Example: NOAA TM ERL ARL-119 (PB83-204347). Questions may be addressed to Programs Office, R/El National Oceanic and Atmospheric Administration Environmental Research Laboratories 325 Broadway Boulder, CO 80303 (303) 497-6212 FTS: Access Code + 320-6212 IV CONTENTS Index code* Page FOREWORD -- iii A GUIDE FOR USERS AERONOMY LABORATORY AIR RESOURCES LABORATORY ATLANTIC OCEANOGRAPHIC AND METEOROLOGICAL LABORATORY CLIMATE MONITORING AND DIAGNOSTICS LABORATORY FORECAST SYSTEMS LABORATORY GEOPHYSICAL FLUID DYNAMICS LABORATORY GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY NATIONAL SEVERE STORMS LABORATORY PACIFIC MARINE ENVIRONMENTAL LABORATORY SPACE ENVIRONMENT LABORATORY WAVE PROPAGATION LABORATORY APPENDIX: FEDERAL-STATE COOPERATIVE PROGRAM IN ATMOSPHERIC MODIFICATION RESEARCH ABOUT THE AUTHOR INDEX AUTHOR INDEX " IV AL 1 AR 15 AO 45 CM 63 FS 75 GF 83 GL 95 NS 106 PM 125 SE 140 WP 156 AP 190 -- 200 __ 201 *See AUTHOR INDEX, p. 201. Digitized by the Internet Archive in 2012 with funding from LYRASIS Members and Sloan Foundation http://archive.org/details/environmentalrOOenvi ERL Publication Abstracts FY 1991 AERONOMY LABORATORY AL-001 ALBRTTTON, D.L., F.C. FEHSENFELD, and A.F. TUCK. Instrumental requirements for global atmospheric chemistry. Science 250:75- 81 (1990). The field of atmospheric chemistry is data-limited, primarily because of the challenge of measuring the key chemical constituents in the global environment. Several recent advances, however, in rugged, portable, remote-sensing, ground-based instrumentation and accurate, fast-response airborne instrumentation have provided powerful tools for the understanding of stratospheric ozone, particularly in polar regions. Current discoveries of the role of heterogeneous chemical processes point to the need for better techniques for characterization of stratospheric aerosols. In the troposphere, advances in in situ, sensitive methods for detecting reactive nitrogen compounds have demonstrated the role that these compounds have in controlling global oxidation processes, but better measurements of the reservoir species by which the long-range transport of pollutant- reactive nitrogen compounds is thought to occur are urgently needed. The role of hydrocarbons, particularly those of natural origin, in ozone formation in rural areas has focused attention on the requirement for better speciation of these ubiquitous compounds. Lastly, rigorous instrument intercomparison experiments have provided unbiased estimates of measurement capabilities. AL-002 Angevine, W.M., D.A. CARTER, W.L. ECKLUND, and K.S. GAGE. A new technique for temperature profiling using RASS. Preprint Volume, International Conference on Radar Meteorology, Paris, France. American Meteorological Society, 241-244 (1991). No Abstract. AL-003 Angevine, W.M., D.A. CARTER, W.L ECKLUND, and K.S. GAGE. Temperature profiling using a 915 MHz wind profiler with RASS. The Second Symposium on Tropospheric Profiling: Needs and Technologies in Boulder, CO (1991). Extended Abstract. AL-004 Balsley, B.B., D.A. CARTER, A.C. Riddle, W.L. ECKLUND, and K.S. GAGE. On the potential of VHF wind profilers for studying cloud dynamics and deep convection in the tropics. Bulletin of the American Meteorological Society 72(9):1 355-1360 (1991). In this paper we provide a set of examples to demonstrate the potential of VHF radar wind profilers for studying tropical convection processes. Our examples were extracted from data obtained from the NOAA/CU Pacific Profiler Network, which has been in operation for a number of yean and is currently being expanded. AL-005 Brune, W.H., J.G. Anderson, D.W. Toohey, D.W. FAHEY, S.R. Kawa, R.L Jones, D.S. McKenna, and L.R. Poole. The potential for ozone depletion in the Arctic polar stratosphere. Science 252:1260-1266 (1991). The nature of the Arctic polar stratosphere is observed to be similar in many respects to that of the Antarctic polar stratosphere, where an ozone hole has been identified. Most of the available chlorine (HC1 and CIONO2) was converted by reactions on polar stratospheric clouds to reactive CIO and CI2O2 throughout the Arctic polar vortex before midwinter. Reactive nitrogen was converted to HNO3, and some, with spatial inhomogeneity, fell out of the stratosphere. These chemical changes ensured characteristic ozone losses of 10 to 15% at altitudes inside the polar vortex where polar stratospheric clouds had occurred. These local losses can translate into 5 to 8% losses in the vertical column abundance of ozone. As the amount of stratospheric chlorine inevitably increases by 50% over the next two decades, ozone losses recognizable as an ozone hole may well appear. AL-006 Burkholder, J.B., R.R. Wilson, T. Gierczak, R. Talukdar, S.A. McKeen, J.J. Orlando, and A.R. RAVISHANKARA. Atmospheric fate of CF3Br, CF2Br2, CF2aBr, and CF2BrCF2Br. Journal of Geophysical Research 96(D3):5025-5043 (1991). The temperature dependent UV absorption cross sections of the haloalkanes CFjBr, CF^Br, CF^ri and CF^rCFiBr are reported. The UV absorption cross sections were measured over the temperature range 210 to 296 K and the wavelength range 190 to 320 nm. Upper limits of the rate coefficients for the reactions of OH with CF3Br, CF^r^ CF2ClBr, and CFiBrCF^r were also determined using both pulsed photolysis and flow tube techniques. The rate coefficients at 296 K were found to be <1.2 x 10-16, <1.5 * 10-16, <5.0 x 10-16, and <1.5 x 10-16 cm3 molec-i s-i for CFsBr, CF^Br, CF^r^ and CF^rCF^r, respectively. The UV absorption cross section data and OH reaction rate coefficients of these species were combined with a one-dimensional model to yield atmospheric lifetimes of 65, 16, 3.2, and <20 years for CF3Br, CF2ClBr, CF^r^ and CF2BrCF2Br, respectively. AL-007 CARTER, D.A., W.L. ECKLUND, J.R. MCAFEE, K.S. GAGE, T. Keenan, and M. Manton. Results from the first year of observations using the Darwin VHF profiler. Preprints Volume, International Conference on Radar Meteorology, Paris, France. American Meteorological Society, 288-291 (1991). No Abstract. AL-008 CLARK, W.L., T.E. VANZANDT, K.S. GAGE, F.E. Einaudi, J.W. Rottman, and S.E. Hollinger. Combined flatland ST radar and digital- barometer network observations of mesoscale processes. Preprint Volume, International Conference on Radar Meteorology, Paris, France. American Meteorological Society, 292-295 (1991). No Abstract. AL-009 CLARK.W.L., T.E. VANZANDT, J.M. WARNOCK, F.E. Einaudi, and J. W. Rottman. Enhancement of the Flatland wind profiler with a 6-station mesoscale digital barometer network. The Second Symposium on Tropospheric Profiling: Needs and Technologies in Boulder, CO (1991). Extended Abstract. AL-010 Currier, P.E., S.K. Avery, B.B. Balsley, K.S. GAGE, and W.L. ECKLUND. Use of two wind profilers for precipitation studies. Preprint Volume, International Conference on Radar Meteorology, Paris, France. American Meteorological Society, 71-72 (1991). To estimate raindrop size distributions aloft, we fit a theoretical doppler spectrum to observed doppler power spectra measured by a 915 MHz profiler, while using the clear-air information supplied by a 50 MHz profiler. To derive the theoretical doppler spectrum several assumptions have been made. Model derived rainfall rates compare favorably with locally measured rain gauge based estimates. AL-011 Dabberdt, W.F., H.L. Cole, P. Hildebrand, T Horst, Y.H. Kuo, C. Martin, K.S. GAGE, W.L. ECKLUND, R. Strauch, and E.R. WESTWATER. The Integrated Sounding System--A new observing system for mesoscale research. Presented at the Seventh AMS Symposium on Meteorological Observations and Instrumentation, New Orleans, LA (1991). No Abstract. AL-012 Dabberdt, W.F., C. Martin, H.L. Cole, P. Hildebrand, T.Horst, Y.H. Kuo, K.S. GAGE, W.L. ECKLUND, R. Strauch, E.R. WESTWATER, H. Revercomb, and W.L. Smith. An integrated data assimilation and sounding system. Preprint Volume, International Conference on Radar Meteorology, Paris, France. American Meteorological Society, 276-299 (1991). No Abstract. AL-013 Danielsen, E.F., R.S. Hipskind, W.L. Starr, J.F. Vedder, S.E. Gaines, D. Kley, and K.K. KELLY. Irreversible transport in the stratosphere by internal waves of short vertical wavelength. Journal of Geophysical Research 96:17,433-17,452 (1991). The U-2 aircraft was instrumented and flown in the stratosphere during the Stratosphere Troposphere Exchange Project's experiments of April 1984 to provide a set of simultaneous measurements by fast responding sensors that would aid in the identification of the modes of cross-jet transport. The measurements confirm the preexperimental deductions that transport is dominated by waves, not by large-scale circulations. Monotonic gradients of trace constituents normal to the jet axis, with upper stratospheric tracers increasing poleward and tropospheric tracers increasing equatorward, are augmented by large-scale confluence as the jet intensified during cyclogenesis. These gradients are rotated, intensified, and significantly increased in area as their mixing ratio surfaces are folded by the differential transport of a very low frequency, transverse wave. The quasi-horizontal transport produces a laminar structure with stable layers rich in upper stratospheric tracers alternating vertically with less stable layers rich in tropospheric tracers. The transport proceeds toward irreversibility as higher frequency, shear-gravity waves extend the folding to smaller horizontal scales. It becomes irreversible when these short waves actually fold the isentropic surfaces and small-scale mixing develops. The progression to higher wave numbers is a discrete, not a continuous, cascade with major gaps in the observed horizontal wavelengths. The wave modes are identified by matching the observed amplitudes and phases against those obtained by linear perturbation theory. Prior to mixing, the wave-generated perturbations maintain the correlations produced by advecting the larger-scale mean gradients; thus the high resolution measurements support the linear turbulence closure assumption. AL-014 ECKLUND, W.L., D.A. CARTER, K.S. GAGE, A.C. Riddle, and B.B. Balsley. Prospects for lower tropospheric wind profiling in the tropics. Preprint Volume, International Conference on Radar Meteorology, Paris, France. American Meteorological Society, 249-252 (1991). No Abstract. AL-015 ECKLUND, W., D. CARTER, K. GAGE, A. Riddle, and B. Balsley. Tropical wind profiling at 915 MHz. The Second Symposium on Tropospheric Profiling: Needs and Technologies in Boulder, CO (1991). Extended Abstract. AL-016 FAHEY, D.W. Application of the NO/O3 chemiluminescence technique to measurements of reactive nitrogen species in the stratosphere. SPIE - The International Society for Optical Engineering 1433:212-223 (1991). The NO/0 3 chemiluminescence technique provides selectivity and high sensitivity for the measurement of NO in a flowing system. The technique requires the addition of reagent O3, produced by electric discharge in O2, and the detection of photons near lu.m wavelength with a photomultiplier tube. The technique has been used extensively in measurements of reactive nitrogen species in the atmosphere with detection limits reaching as low as a few parts per trillion by volume (pptv) for NO. With a gold catalyst, other oxides of nitrogen can be converted to NO and detected, thereby providing a measurement of the sum of reactive nitrogen species, designated NOy. An instrument that measures NO or NOy on board the NASA high altitude ER-2 aircraft will be described. Missions of this aircraft have addressed stratospheric ozone depletion in both polar regions in recent years. The polar data provides evidence for the condensation of reactive nitrogen species on aerosol particles and for the removal of reactive nitrogen through the sedimentation of aerosol particles. These processes facilitate the destruction of ozone through catalytic cycles involving reactive chlorine species. In the future, similar instruments will address the chemical impact of proposed supersonic aircraft for civilian transport. AL-017 Fried, A., B. Henry, D.D. PARRISH, J.R. Carpenter, and M.P. Buhr. Intercomparison of tunable diode laser and gas filter correlation measurements of ambient carbon monoxide. Atmospheric Environment 25A:2277-2284 (1991). An intercomparison that involved a standards intercomparison, interferant spiking tests and simultaneous ambient measurements was carried out between two CO measurement systems: a tunable diode laser absorption spectrometer (TDLAS) and a gas filter correlation, non- dispersive infrared absorption instrument (GFC). Both the TDLAS and the GFC techniques responded to CO. No major interferences were found for the TDLAS system; tested species included H2O, O3 and OCS. The GFC instrument exhibited no interference from H2O or O3, but only a relatively high upper limit could be placed on the O 3 interference. For CO measurements in ambient air at levels from 100 to 1500 ppbv, the results from the two instruments agreed within their combined uncertainties. On average the GFC technique was 6% higher than the TDLAS system, and there was no systematic, constant offset. The precision of the GFC instrument was about 10%, and the precision of the TDLAS system was better than 4%. AL-018 GAGE, K.S., B.B. Balsley, W.L. ECKLUND, D.A. CARTER, and J.R. MCAFEE. Wind profiler related research in the tropical pacific. Journal of Geophysical Research. 96:3209-3220 (1991). This paper is concerned with the application of wind-profiling doppler radar technology to tropical atmospheric research. Examples of the use of wind profilers in the tropics are drawn from the Aeronomy Laboratory's wind profilers located on Pohnpei, Micronesia (7°N, 158°E), and Christmas Island (2°N, 157°W). The Pohnpei wind profiler was constructed on 1984 and has been used exclusively to observe vertical motions. The Christmas Island wind profiler has observed horizontal and vertical velocities routinely since 1986. These two wind profilers form part of a planned trans -pacific network of wind-profiling radars that will eventually span the tropical pacific. AL-019 GAGE, K.S., B.B. Balsley, W.L ECKLUND, R.F. Woodman, and S.K. Avery. A trans-pacific network of wind-profiling doppler radars for tropical atmospheric research. EOS 7 1 (50): 1 851-1854 (1990). No Abstract. AL-020 GAGE, K.S., J.R. MCAFEE, D.A. CARTER, W.L. ECKLUND, and G.C. REID. A first look at long-term vertical motions over the central equatorial Pacific using the Christmas Island wind profiler. Proceedings of the 15th Annual Climate Diagnostics Workshop, Asheville, NC (1990). No Abstract. AL-021 GAGE, K.S., J.R. MCAFEE, W.L. ECKLUND, D.A. CARTER, A.C. Riddle, and B.B. Balsley. The Christmas Island wind profiler: A prototype VHF wind-profiling doppler radar for the tropics. Preprint Volume, International Conference on Radar Meteorology, Paris, France. American Meteorological Society, 284-287 (1991). No Abstract. AL-022 GAGE, K.S., J.R. MCAFEE, W.L. ECKLUND, D.A. CARTER, A.C. Riddle, and B.B. Balsley. The Christmas Island wind profiler: A prototype VHF wind-profiling doppler radar for the tropics. The Second Symposium on Tropospheric Profiling: Needs and Technologies in Boulder, CO (1991). Extended Abstract AL-023 GAGE, K.S., J.R. MCAFEE, and G.C. REID. On the inference of diabatic heating rates from long-term measurements of vertical motion using a VHF wind profiler. The Second Symposium on Tropospheric Profiling: Needs and Technologies in Boulder, CO (1991). Extended Abstract. AL-024 Gierczak, T., R. Talukdar, G.L. Vaghjiani, E.R. Lovejoy, and A.R. RAVISHANKARA. Atmospheric fate of hydrofluoroethanes and hydrofluorochloroethanes: 1. Rate coefficients for reactions with OH. Journal of Geophysical Research 96(D3):5001-501 1 (1991). The rate coefficients for the reactions of OH with five halocarbons [CF3CH2F (HFC 134a), CF3CHCIF (HCFC 124), CF3CHCI2 (HCFC 123), CH3CHF2 (HCF 152a), and CH3CF2CI (HCFC 142b)], which are proposed as alternatives to chlorofluoromethanes, have been measured. A pulsed photolysis system and a discharge flow apparatus were used to measure the rate coefficients between approximately 210 and 425 K. Use of the complementary techniques enabled identification of systematic errors and minimization of these errors. The obtained values are compared with values previously measured by other groups. This data base is used in the subsequent paper to calculate the atmospheric lifetimes of the five compounds. AL-025 Greenblatt, G.D., J.J. Orlando, J.B. Burkholder, and A.R. RAVISHANKARA. Absorption measurements of oxygen between 330 and 1140 run. Journal of Geophysical RsseaxcJi 95(D11):18,577-18,582 (1990). The absorption spectrum of O2 and O2-O2 collision pairs were measured over the wavelength range from 330 to 1 140 nm using pressures of O2 from 1 to 55 atm at 298 K. Absorption cross sections, pressure dependences, band centers, and full widths at half maximum of the observed absorption bands centered at 343.4, 360.5, 380.2, 446.7, 477.3, 532.2, 577.2, 630.0, 688, 762, and 1065.2 nm are reported. The absorption bands centered at 360.5, 380.2, and 477.3 nm were also measured at 196 K and their temperature dependences were characterized. AL-026 Hanson, D.R., and A.R. RAVISHANKARA. The loss of CF2O on ice, NAT, and sulfuric acid solutions. Geophysical Research Letters 18(9):1699-1701 (1991). We measured the first -order rate coefficients for CF2O on solid surfaces, ice and HN03-treated ice, and on sulfuric acid solutions that coated the inside wall of a flow tube. We determined an upper limit for the uptake coefficient, y, of -3x10-6 for CF2O on ice and HN03-treated ice. A value for y on a 60% (by weight) sulfuric acid solution of 3(+2/-3)xl0-* was measured and we observed a higher value over 40% acid, y= 6x10-5 (±30%). The loss of CF2O on stratospheric particles is a very slow process and will be insignificant for events that occur on timescales of a year, such as the annual polar chlorine activation phenomena. AL-027 Hanson, D.R., and A.R. RAVISHANKARA. The reaction probabilities of CIONO2 and N2O5 on polar stratospheric cloud materials. Journal of Geophysical Research 96(D3):508 1-5090 (1991). The reaction probabilities, y, of CIONO2 and N2O5 on ice and nitric acid trihydrate (NAT) surfaces were determined, using reactant concentrations that are typical of the lower stratosphere, by measuring the first-order reactant loss rate coefficients over the substrate located on the walls of a fast-flow reactor. Reactants were detected using chemical ionization mass spectrometry, a sensitive technique which allows the use of low reactant concentrations. The reaction probabilities obtained for CIONO2 are 0.3 (±°-7-o.i) on pure ice, 0.006 (±30%) over a NAT surface, and 0.3 (±0.7.0.!) on an HCl-doped NAT surface. Those for N2O2 are: 0.024 (±30%) on pure ice, 0.0006 (±50%) on a NAT surface, and 0.0032 (±30%) on an HCl-doped NAT surface. We observed that na ice surface will be converted into a less reactive HN03-doped ice surface in a relatively short time, and we present arguments that this surface consisted of a NAT layer. The large differences between our results and previous measurements for some of these g can be attributed to the relatively large reactant concentrations used in the previous work. The major implications of this work for polar stratospheric chlorine activation are: an efficient loss of CIONO2 on pure ice surfaces, a very rapid rate for the reaction CIONO2 + HC1 on NAT surfaces, and that pure ice surfaces will become "passivated" when coated with one monolayer of NAT crystal. AL-028 Hanson, D.R., and A.R. RAVISHANKARA. The reaction probabilities of CIONO2 and N205 on 40 to 75% sulfuric acid solutions. Journal of Geophysical Research 96(D9):17,307-17,314 (1991). A wetted-wall flow tube was used to measure the reaction probabilities, y, of ClONO^and N2O5 on sulfuric acid surfaces. The reaction probabilities were determined from first-order wall loss rate coefficients measured over sulfuric acid slowly flowing down the inside wall of the flow tube. Sulfuric acid content was varied from 40 to 75% by weight, and measurements were conducted at temperatures characteristic of the stratosphere. We determined the reaction piobabilities of N2O5 to be 0.12 ± 0.03 over 40% acid at 215 K, 0.14 ± 0.03 over 60% acid at 215 K and 0.10 ± 0.02 over 70 and 75% acid at 220 and 230 K, respectively. The y for CIONO2 increased from 2x10-4 over 75% acid at 230 K to 6.4 x 10-2 over 40% acid at 215 K; these are a factor of 2 lower than a previous determination performed under the same conditions. When we introduced HC1 into the flow tube, we detected negligible uptake over the 65 and 70% acid solutions, y < 3 x 10-5, and a small uptake, y= 4 x 10 -*, for HC1 onto 60% acid at 215 K. We did not detect a significant enhancement in the First-order loss rate coefficients for CIONO2 over these solutions in the presence of HC1. Thus the reaction CIO NO 2 + HC1 occurring on 40-75 wt. % sulfuric acid solutions will not be a significant source of activated chlorine in the stratosphere; however, loss of N2O5 and ClONO 2 could affect the NDX and C!Ox concentrations. AL-029 Harder, J., and G. MOUNT. Long path differentia] absorption measurements of tropospheric molecules. Proceedings, SPIE Conference, Orlando, FL, April 1991. Remote Sensing of Atmospheric Chemistry 1491:33^2(1991). The measurement of the important atmospheric molecules O3, NO2, CH2O, H2O, NO3, and HONO can be measured using long path differential absorption spectroscopy. The experiment is located at the Fritz Peak Observatory, 17 km west of Boulder, Colorado. This site permits both the measurement of clean continental air during times of westerly air flow, as well as polluted urban air during easterly up- slope episodes. The spectrograph used in this study is a low resolution double crossed Czemy-Tumer, with a well matched receiving telescope. This spectrograph uses a 1 x 1024 element Reticon diode array detector to measure the molecular absorption spectra of these molecules in 40 nm bands in the near ultraviolet-visible region. The total optical path for this experiment is 20.6 km, and the path is folded by a 121 element retro-reflector array thereby allowing the light source and spectrograph to be in the same location. Deduction of atmospheric concentrations these molecules over this path is accomplished by using a least squares procedure that employs the method of singular-value decomposition. AL-030 Kawa, S.R., D.W. FAHEY, S. SOLOMON, W. H. Brune, M.H. Proffitt, D.W. Toohey, D. E. Anderson, Jr., L.C. Anderson, and K.R. Chan. Interpretation of aircraft measurements of NO, CIO, and O3 in the lower stratosphere. Journal of Geophysical Research 95(D11):18,597-18,609 (1990). Results are presented from an October 17, 1988, flight of the NASA ER-2 stratospheric research aircraft. The flight sampled a nearly constant air mass at 20 km altitude, near 39°N latitude, from before sunrise until near noon. The instrumentation on board simultaneously measured NO, CIO, O3, temperature, and pressure. The measurements are combined with modeled photodissociation coefficients and known reaction kinetics to infer abundances of other important species, and the results are compared to previous estimates as a test for consistency in our understanding of the photochemical processes governing the species distributions. NO and CIO are observed to increase after sunrise, consistent with photolysis of nighttime reservoirs. The derived values for NO2, CIONO2, and N2O5 near midday are 320 (± 190) pptv, 170 (±120) pptv, and 200 (±150) pptv, respectively, and are in good agreement with most previous measurements and model estimates. The slope of the NO- (=NO + NO) change with time is a sensitive function of the shape of the /nce versus zenith angle curve at zenith angles above about 75°. This makes the derived value for N2O5 dependent on the model method used to compute the solar flux, with a detailed treatment of multiple scattering required for good results. Subtracting the sum of the measured and derived values for the nitrogen species from the average of measurements of total reactive nitrogen (NOy) on other flights, we obtain an estimate for the mixing ratio of HNO3 of 3.3 (±1.7) ppbv. This value for HNO3 and the HNOj/NOy fraction are in good agreement with values measured by the ATMOS experiment. The HNO3 and NO 2 values are further used to estimate a daytime average OH mixing ratio of 0.6 pptv, which is consistent with extrapolation of previous measurements at higher altitudes. AL-031 KELLY, K.K., A.F. TUCK, and T. Davies. Wintertime asymmetry of upper tropospheric water between the Northern and Southern Hemispheres. Nature 353:244-247 (1991). Water Vapour is an important greenhouse gas 1-3 and yet its Abundance in the upper troposphere is poorly known. Upper-tropospheric water vapour is particularly important despite its low mixing ratios, because it has large effects on the flux of infrared radiation near the tropopause2. In addition, the distribution and supply of water vapour are central to cloud formation; the effects of cloud on the Earth's radiation budget are in turn central to understanding the climate response to increasing atmospheric concentrations of greenhouse gases. From airborne measurements of total water (vapour plus ice crystal)* during the winters of 1987 in the Southern Hemisphere and of 1988- 89 in the Northern Hemisphere, we find that the upper troposphere in middle, subpolar and high latitudes is a factor of 2-4 drier during austral winter than during boreal winter. As the lower-latitude air moves towards the pole in austral winter, it is forced to cool to lower temperatures than in the north — more of the water vapour therefore condenses to form ice crystals, which then precipitate, thereby removing moisture from the air mass. Clearly, climate models must be able to reproduce this asymmetry if their predictions are to be credible. We also note that the asymmetry in water vapour implies an asymmetry in the production rate of the hydroxyl radical, and hence in the tropospheric chemistry of each hemisphere, for example in the rate of methane loss5. AL-032 Liu, C-M, and S.C. LIU. A study of the winter surface of ozone in Taipei. Meteorological Society of Japan 161-169 (1991). In the Taipei basin in winter, surface ozone concentration usually displays a diurnal pattern with double peaks, one in the early morning, the other in early afternoon. The occurrence probability of double-peak days in a particular winter can be as high as 45%. In this study, a field experiment is carried out to test a hypothesis proposed by the authors in a previous paper to explain the formation of the double peaks. The field experiment shows that the double peak days lend to appear after the passage of a cold-front over northern Taiwan. At that time the Taipei basin is characterized by a strong northeasterly monsoon, low temperature, and overcasting sky with occasional light rain. An upstream hilltop ozone station shows that a background ozone of about 30 ppbv is carried by the monsoon into the Taipei basin. Effective transport processes replenish the near surface ozone that is otherwise titrated out by vehicle-emitted nitrogen oxide (NO). The diumal ozone double peaks occur at times when the NO concentration is at its minimum which are the result of the combined effect of diurnal traffic pattern and transport processes. AL-033 Malci, A.G., J.S. Wells, and J.B. Burkholder. High-resolution measurements of the bands of carbonyl sulfide between 2510 and 3150 cm-i. Journal of Molecular Spectroscopy 147:173-181 (1991). The four strongest absorption bands of OCS in the region from 2500 to 3150 cm-i have been measured with FTS spectrometers with effective resolutions of about 0.010 cm-i or better. A total of 25 different vibrational transitions have been identified in the spectrum and have been analyzed to obtain improved band centers and rovibrational constants. Included in the bands identified are a few transitions due to the less abundant isotopomers, l^O 12CWS, 16012C33S, 1601302S, and 18012C32S. Relative values are given for the transition moments of some of the overlapping bands. AL-034 MCAFEE, J.R., K.S. GAGE, D.A. CARTER, and G.C. REE). An analysis of Christmas Island winds: The annual, interannual, and intraseasonal variability. Proceedings of the 15th Annual Climate Diagnostics Workshop, Asheville, NC (1990). No Abstract. AL-035 McKeen, S.A., E.-Y. Hsie, and S.C. LIU. A study of the dependence of rural ozone on ozone precursors in the eastern United States. Journal of Geophysical Research 96(D8): 15,377-15,394 (1991). A comprehensive three-dimensional mesoscale model, with detailed treatment of meteorology and photochemistry, is applied to the eastern United States and southeastern Canada to address the issue of ozone production over rural regions. Simulations with various anthropogenic emission reductions over a 4-day high-pressure period, for which the eastern U.S. experienced elevated O3 levels, are compared to the results of a reference case that incorporates the most recent National Acid Precipitation Assessment Program (1985) emissions inventory. Our focus is on the relative effects of anthropogenic NO, versus nonmethane hydrocarbons (NMHC) emission reductions on O3 concentrations within this photochemical regime. The model results are consistent with earlier studies that predict a reasonably high O3 sensitivity to NMHC emission reductions, and O3 increases for NOx emission reductions in regions of strong urban influence. However, the total area that exhibits these distinctly urban characteristics comprises less than 10% of the continental area within the model. O3 production for the majority of the eastern United States is found to be limited by NO, availability rather than NMHC. Thus the sensitivity to NOx emission reductions averaged over the continental regions of the model domain is about a factor of 3 higher than that of NMHC. Because of large uncertainties in the natural and anthropogenic NMHC emissions, additional sensitivity runs are performed with increased anthropogenic NMHC emissions and natural NMHC emissions excluded. These alterations do not effect our basic conclusions with respect to rural O3 formation but do impact urban locations. When anthropogenic NMHC emissions are increased by a factor of 4, control of NO, emissions has nearly the same effect in both urban and rural areas. The nonlinear nature of regionally averaged O3 with respect to anthropogenic and natural precursors is also illustrated from the results of the sensitivity studies. AL-036 McKeen, S.A., E.-Y., Hsie, M. Trainer, R. Tallamraju, and S.C. LIU. A regional model study of the ozone budget in the eastern United States. Journal of Geophysical Research 96(D6): 10,809-1 0,845 (1991). In order to better understand the photochemical and meteorological processes controlling regional scale air quality problems such as ozone formation, we have developed a three-dimensional Eulerian model and applied this model to a high-pressure period (July 4 to July 7, 1986) over the eastern United States. Meteorological and physical variables from a three-dimensional primitive-equation model are used to drive the transport parameters over a grid with 60x60 km2 horizontal resolution, and 15 unequally spaced vertical layers extending from the ground to roughly 15 km. The treatment and incorporation of the dynamic model, the transport model, surface deposition, emission of anthropogenic and natural O3 precursors, the chemical mechanism for 35 individual species, solar radiation and the numerical methods are discussed in detail. Model performance is tested by comparing model predicted O3 concentrations with observations from the U.S. Environmental Protection Agency ozone-monitoring network. Although a significant correlation between model and observed O3 is found, systematic discrepancies also exist and are discussed in relation to the basic model formulation, and variability in the observed O3. Additionally, a comparison of time-averaged NO„ and anthropogenic nonmethane hydrocarbon (NMHC) concentrations to relatively long term observations provides a qualitative assessment of the model's ability to simulate certain aspects of these O3 precursors from the few available observations. The model is used as a diagnostic tool to analyze various aspects of regional scales O3 formation and the budgets of the primary O3 precursors. Ozone formation over much of the continental model domain is shown to be NOx limited. On the other hand, for midday NO, levels greater than about 4 or 5 ppbv, O3 formation is generally suppressed because of the low NMHC to NOx ratios (1 to 7) that are characteristic of the emissions inventory. Regional-scale budget analyses show that very little NOx or NMHC is transported to the free troposphere for the high-pressure conditions of this study and in the absence of a significant subgrid-scale vertical mixing process (i.e., efficient cumulus transport). We calculate a net turnover time of about 1.5 days for continental O3 below 1800 m with in situ photochemical formation being balanced by photochemical loss and transport off the American continent. The results of this work are intended to serve as a baseline for further model development. AL-037 McKenzie, R.L., P.V. Johnston, C.T. McElroy, J.B. Kerr, and S. SOLOMON. Altitude distributions of stratospheric constituents from ground-based measurements at twilight. Journal of Geophysical Research 96(D8):15,499-15,51 1 (1991). A technique for extracting height profiles from ground-based column measurements at twilight is introduced. Its sensitivities to chemical processes, initialization, and air mass factors are investigated. The method is applied to observations made at Lauder, New Zealand, in 1987. The technique provides information on the vertical structure of atmospheric absorbers such as ozone or NO2 from the surface to about 50 km and is particularly valuable for identifying the influence of pollution on such measurements. When tropospheric pollution is low, it yields profiles in reasonable agreement with model predictions and with satellite measurements. AL-038 McKeown, PJ., M.V. Johnston, and D.M. MURPHY. On-line single-particle analysis by laser desorption mass spectrometry. Analytical Chemistry 63:2069-2073 (1991). No abstract. AL-039 Mlynczak, M.G., and S. SOLOMON. Middle atmosphere heating by exothermic chemical reactions involving odd-hydrogen species. Geophysical Research Letters 18(l):37-40 (1991). We calculate the rate of heating that occurs in the middle atmosphere (50 - 105 km) due to four exothermic reactions involving members of the odd-hydrogen family. These reactions are O + OH -+O2 + H, H + O2+M -> HO2+ M, H + O3 -> OH + O2,and0 + H02->OH + 02- The energy lost from vibrationally excited OH (produced in the third reaction) by spontaneous emission is explicitly accounted for by using detailed kinetic models, so that only a portion of the exothermicity of this reaction is converted into heat. The heating rates due to these four reactions are found to rival the oxygen -related heating rates conventionally considered in models of the middle atmosphere, e.g., those due toO + 0 + M-> O2 + M, O + O2 + M -» O3 + M, O2 + hv -* O + O, and03 + hv -* O + O2. The conversion of chemical potential energy into molecular translalional energy (heat) by these odd-hydrogen reactions is a significant source of energy in the middle atmosphere which has not been previously considered. AL-040 Mlynczak, M.G., and S. SOLOMON. On the efficiency of solar heating in the middle atmosphere. Geophysical Research Letters 18(7): 1201 -1204 (1991). We calculate the efficiency at which solar ultraviolet radiation absorbed in the Hartley band of ozone is directly converted to heat in the terrestrial mesosphere and lower thermosphere (50-110 km). The ozone molecule undergoes photolysis to yield the excited species 0( ID) and02('A) with a quantum yield of about 0.9. Spontaneous emission from O 2( !A) and from O2OX) (excited by energy transfer from O(iD)) significantly decreases the amount of energy available from heat. Similarly, we calculate the efficiency at which solar ultraviolet radiation absorbed by O2 in the Schumann-Runge continuum is directly converted to heat in the lower thermosphere (95-110 km). The O 2 undergoes photolysis and the excited product O(iD) is generated. Spontaneous emission from O2OX) (excited by energy transfer from O(iD)) reduces the amount of energy available for heat in the lower thermosphere. The consideration of these energy transfer and loss processes results in significantly reduced heating rates as compared to those conventionally calculated in models of the middle atmosphere. AL-041 Nastrom, G.D., T.E. VANZANDT, W.L. CLARK, K.S. GAGE, and J.M. WARNOCK. Measurement of large-scale vertical velocity using clear-air doppler radar. The Second Symposium on Tropospheric Profiling: Needs and Technologies in Boulder, CO (1991). No Abstract. AL-042 NEFF, W., J. JORDAN, J. GAYNOR, D. WOLFE, W. ECKLUND, D. CARTER, and K. GAGE. The use of 915 MHz wind profilers in complex terrain and regional air quality studies. Seventh Joint Conference on Applications of Air Pollution Meteorology (1990). No Abstract. AL-043 Nelson, D.D., Jr., A. Schiffman, D.J. Nesbitt, J.J. Orlando, and J.B. Burkholder. H + O3 Fourier-transform infrared emission and laser absorption studies of OH(X2TI) radical: An experimental dipole moment function and state-to-state Einstein A coefficients. Journal of. Chemical Physics 93(10):7003-7019 (1990). The relative intensities of 88 pairs of rovibrational transitions of OH(X2fI) distributed over 16 vibrational bands (v'<9, Av = -1, -2) have been measured using Fourier transform infrared (FTTR) emission/absorption spectroscopy. Each pair of transitions originates from a common vibrational, rotational, and spin-orbit state, so that the measured relative intensities are independent of the OH number density and quantum state distribution. These data are combined with previous v = 1 <— 0 relative intensity absorption measurements and v =0,1, and 2 permanent dipole moments to determine the OH dipole moment function as a cubic polynomial expanded about re, the equilibrium bond length. The relative intensities provide detailed information about the shape of the OH dipole moment function \i{r) and hence the absolute Einstein A coefficients. The intensity information is inverted through a procedure which takes full account of the strong rotation- vibration interaction and spin uncoupling effects in OH to obtain the dipole moment function (with 95% confidence limits): |i(r)= 1.6502(2) D + 0.538(29) D/A (r -re) - 0.796(51) D/A2(r -rJ2 - 0.739(50) D/A3 (r- re)3, with a range of quantitative validity up to the classical turning points of the v = 9 vibrational level (i.e., from 0.70 to 1.76 A). The u.(r) determined in this study differs significantly from previous empirical analyses which neglect the strong effects of rotation -vibration interaction and spin uncoupling. The present work also permits distinguishing between the various ab initio efforts. Best agreement is with the dipole moment function of Langhoff, Wemer, and Rosmus [J. Mol. Spectrosc. 118, 507 (1986)], but their theoretical predictions for higher overtone transitions are still outside of the 2o experimental error bars. Absolute Einstein A coefficients from the present \i.(r) are therefore presented for P ,Q, R, branch transitions for Av = 1, 2, 3, v'5 9,/' S 14.5, in order to provide the most reliable experimental numbers for modeling of near IR atmosphere OH emission phenomena. AL-044 Orlando, J.J., J.B. Burkholder, A.M.R.P. Bopegedera, and C.J. HOWARD. Infrared measurements of BrO QO-Ylia)- Journal of Molecular Spectroscopy 145:278-289 (1991). Thcu = 1-0 band of BrO in the X2FI3/2 spin state was measured using high-resolution Fourier transform absorption spectroscopy. One hundred and thirty transitions were assigned and analyzed to determine the band origins, rotational constants, and distortion constants for both 79BrO and 8IB1O. The "0=1-0 band strength was determined to be 5.04 ± 0.80 cm-2 atm-l using a Herman-Wallis type analysis. The A2lTX2n transition were determined relative to the calculated TR intensities. The absorption cross section at the peak of the (7,0) band at 338.5 nm is (1.4 ± 0.3) x 10-n cm2 molecule-i at 298 K. AL-045 Orlando, JJ., J.B. Burkholder, S.A. McKeen, and A.R. RAVISHANKARA. Atmospheric fate of several hydrofluoroethanes and hydrochlorofluoroethanes. 2. UV absorption cross sections and atmospheric lifetimes. Journal oi Geophysical Research 96:5013-5023 (1991). The temperature dependent UV absorption cross-sections of the hydrochlorofluoroethanes CF3CHFCI, CH3CF2CI, and CF3CHCl2are reported. The UV absorption cross-sections were measured over the temperature range 203 to 295 K and the wavelength range 190 to 230 nm. The hydrofluorocarbons CH3CF2H and CF3CH2F were also studied at 295 K and upper limits for their UV absorption cross-sections over the wavelength range 190 to 230 nm were obtained. The atmospheric lifetimes of these species were calculated using a one-dimensional atmospheric model, using the kinetic data obtained in the previous paper (Gierczak et al. 1991) and the absorption cross-section data obtained in the present study. AL-046 Ortigoso, J., R. Escribano, J.B. Burkholder, and C.J. HOWARD. High-resolution infrared spectrum of the "U 1 band of OCIO. Journal of Molecular Spectroscopy 148:346-379 (1991). The infrared absorption spectrum of the t>i band of OCIO (care must be taken to distinguish it from ClOO, which also exists) has been recorded in the 950 cm-i region, with a Fourier transform infrared spectrometer with an instrumental resolution of -0.004 cm-l. Most lines appear as doublets owing to the spin-rotation interaction present in this molecule. Around 2800 lines have been assigned for the 35C102 species and -800 for the 37QO2 species. In addition, a number of lines of the "hot band", tii + 1)2 - ^2. have been assigned for the 35QO2 species. Effective rotational and spin-rotational spectroscopic constants have been obtained for the ground and the \>i = 1 vibrational states of 35Q02 and 37QO2 and the corresponding band origins have also been determined. Fermi resonance between the 2t>2andt)i bands has been found to be negligible; however, a weak resonance between the K. = 7 levels of v 1 = 1 and the AT, =9 levels of V2 = 2 has been observed. The measured integrated x> 1 band strength is 87± 6 cm-2 atm-i at 300 K. AL-047 PARRISH, D.D., M. Trainer, M.P. Buhr, B.A. Watkins, and F.C. FEHSENFELD. Carbon monoxide concentrations and their relation to concentrations of total reactive oxidized nitrogen at two rural U.S. sites. Journal of Geophysical Research 96:9309-9320 (1991). Concentrations of CO and NOy (total reactive oxidized nitrogen species) were measured simultaneously with many other atmospheric parameters, including SO2 concentration and wind direction, during three field studies (two rural and one suburban). The CO concentrations at the two rural sites can be described approximately by lognormal distributions, with the Scotia, Pennsylvania, site exhibiting higher levels (geometric mean, 214 parts per billion by volume (ppbv); standard deviation of the logarithms, 0.143) than Niwot Ridge, Colorado (geometric mean, 121 ppbv; standard deviation of the logarithms, 0.175). As expected, measurements made at Niwot Ridge when the wind was from the east, the direction of the principal nearby urban area, exhibited the highest CO levels. At Scotia, power-plant- dominated air parcels could be identified by larger [SO 2] to [NOy] ratios and were characterized by smaller [CO] to [NOy] ratios. Simultaneous measurements of [CO] and [NOy] allowed the identification of air parcels that arrived at Niwot Ridge and Boulder (the suburban site) without significant recent anthropogenic input. The CO levels in these parcels were consistent with the tropospheric background concentration of CO at 40°N latitude: approximately 84 ppbv in late summer and 127 ppbv in early spring. The [CO] to [NOy] ratios observed in the Boulder suburban study provide a test for, and are consistent with, available emission inventories for these pollutants. At Niwot Ridge in east winds the observed ratios are consistent with the ratios expected from emission inventories, modified by photochemical transformation on time scales that are reasonable for transport from the location of emission to the measurement site. However, the rural data sets were not able to provide stringent tests of emission inventories. AL-048 Proffitt, M.H., and A.O. Langford. Measuring tropospheric ozone using differential absorption lidar technique. SPIE - The International Society for Optical Engineering 1491:2-6 (1991). Frequent and accurate measurements of ozone many kilometers above the ground are required to monitor changes that may be occurring due to man's activities. Here we describe an application of a differential absorption laser technique that accurately resolves the vertical distribution of tropospheric ozone up to at least 12 km altitude in one minute, day or night. The prototype instrument is located in the Colorado mountains and will serve as the first NOAA ozone lidar within a planned tropospheric monitoring network. AL-049 REID, G.C. Climate. In Quo Vadimus Geophysics for the Next Generation. G.D. Garland and J.R. Apel (ed.). American Geophysical Union, Washington, DC, 45-46 (1991). No abstract. AL-050 REID, G.C. Solar total irradiance variations and the global sea surface temperature record. Journal of Geophysical Research 96(D2):2835-2844 (1991). The record of globally averaged sea surface temperature (SST) over the past 130 years shows a highly significant correlation with the envelope of the 11 -year cycle of solar activity over the same period. This correlation could be explained by a variation in the sun's total irradiance (the solar "constant") that is in phase with the solar-cycle envelope, supporting and updating an earlier conclusion by Eddy (1976) that such variations could have played a major role in climate change over the past millennium. Measurements of the total irradiance from spacecraft, rockets, and balloons over the past 25 years have provided evidence of long term variations and have been used to develop a simple linear relationship between irradiance and the envelope of the sunspot cycle. This relationship has been used to force a one-dimensional model of the thermal structure of the ocean (Hoffert et al., 1980), consisting of a 100-m mixed layer coupled to a deep ocean and including a thermohaline circulation. The model was started in the mid-seventeenth century, at the time of the Maunder Minimum of solar activity, and mixed-layer temperatures were calculated at 6-month intervals up to the present. The total range of irradiance values during the period was about 1%, and the total range of SST was about 1°C. Cool periods, when temperatures were about 0.5°C below present-day values, were found in the early decades of both the nineteenth and twentieth centuries. There is direct evidence for the latter period from the historical SST record and some indirect evidence for the earlier cool period. While many aspects of the study are 10 unavoidably simplistic, the results can be taken as indicating that solar variability has been an important contributor to global climate variations in recent decades. It has probably not been the only contributor, however, and in particular, the growing atmospheric burden of greenhouse gases may well have played an important role in the immediate past. This role likely to become even more important in the near future. AL-051 REID, G.C., S. SOLOMON, and R.R. Garcia. Response of the middle atmosphere to the solar proton events of August-December, 1989. Geophysical Research Letters 18(6):1019-1022 (1991). Intense solar activity during the period August-December 1989 gave rise to several major energetic-particle events, which were accompanied by greatly enhanced ionization rates and NOy production in the polar regions of both hemispheres. A two-dimensional model of the chemistry and dynamics of the middle atmosphere has been used to calculate the production and subsequent fate of the NOy and its effect on ozone concentrations and temperatures. In the sunlit southern polar cap, NO increases as large as a factor of 20 are estimated near 60 km altitude, with column density enhancements of 55%. Corresponding peak ozone depletions of about 20% are calculated near 40 km in late October 1989, with predicted temperature decreases of about 3-3. 5K. Effects in the northern polar regions are considerably smaller, due to the lack of sunlight during the peak phase of the events. AL-052 Riddle, A.C., W.L ECKLUND, K.S. GAGE, and D.S. CARTER. Comparison of UHF and VHF profiler data at Christmas Island. The Second Symposium on Tropospheric Profiling: Needs and Technologies in Boulder, CO (1991). Extended Abstract. AL-053 Rogers, R.R., W.L. ECKLUND, and D.A. CARTER. First results from the Harp boundary-layer radar. Preprints Volume, International Conference on Radar Meteorology, Paris, France. American Meteorological Society, 296-299 (1991). No Abstract. AL-054 Salby, M.L, P. Callaghan, S. SOLOMON, and R.R. Garcia. Chemical fluctuations associated with vertically propagating equatorial kelvin waves. Journal of Geophysical Research 95(D12'):20.491-20.505 (1990). Satellite retrievals of ozone and nitrogen dioxide from the Nimbus-7 Limb Infrared Monitor of the Stratosphere (LIMS) reveal distinct spectral features which are collocated in frequency with Kelvin wave temperature fluctuations. These features represent a significant component of the unsteady variance in retrievals of O3 and nighttime NO2 in the tropics and are very similar to Kelvin wave temperature disturbances. Chemical fluctuations occur symmetrically about the equator, in phase across the tropics, and propagate downward, all consistent with the behavior of equatorial Kelvin waves. The phase structure of ozone perturbations mirrors that of temperature fluctuations in the upper stratosphere and mesosphere, only shifted 180°. The regular phase tilt with altitude disappears in the middle to lower stratosphere, where it is replaced by more or less barotropic behavior. That change in phase structure marks a transition from photochemical control in the upper stratosphere and mesosphere to dynamical control in the lower stratosphere. Fluctuations in NO 2 propagate downward throughout the observed region, with a constant shift of 180° from temperature fluctuations. Only a slight indication of equatorial Kelvin waves is found in nitric acid, in accord with the weaker temperature sensitivity, relatively long lifetime, and small vertical gradient of HNO 3 in the tropics. Fluctuations in ozone are consistent with dynamical and chemical mechanisms operating on that species. The response of ozone in a detailed photochemical calculation driven by observed temperature variability locks into agreement with the observed ozone variability above about 4 mbar, where O3 is under photochemical control. At lower altitudes, vertical transport is able to explain both the magnitude and phase of the observed fluctuations in ozone. The same considerations have only mixed success in explaining the observed variability of nitrogen dioxide. The amplitude of nighttime NO2 fluctuations is underestimated in the photochemical calculation by about a factor of 2. Although large enough to explain the discrepancy, contributions from vertical transport have the wrong phase. Observed fluctuations in daytime NO2, which have a much smaller signal-to-noise ratio, are at odds with both chemical and dynamical explanations. Contamination in the NO2 channel of LIMS by water vapor may be responsible for these discrepancies. AL-055 Talukdar, R., A. Mellouki, T. Gierczak, J.B. Burkholder, S.A. McKeen, and A.R. RAVISHANKARA. Atmospheric fate of CF2H2, CH3CF3, CHF2CF3 andCH3CFCl2: Rate coefficients for reactions with OH and UV absorption cross sections of CH3CFC12- The Journal of Physical Chemistry 95(15):5815-5821 (1991). 11 The absolute rates coefficients for reactions of hydroxyl radical with four halocarbons (CF2H2 (HFC-32), CH3CF3 (HFC- 143a), CF3 CHF2 (HFC- 125), and CH3CFCI2 (HCFC-141b), which are potential substitutes for CFCs, were measured by using the discharge flow-laser magnetic resonance and pulsed photolysis-laser-induced fluorescence techniques between 222 and 393 K. The UV absorption cross sections for HCFC-141b between 190 and 230 nm were also measured as functions of temperature. These kinetics and cross-section data are compared with results from previous studies. These date were incorporated into a one -dimensional photochemical transport model to estimate the tropospheric and atmospheric lifetimes needed to assess the ozone depletion potential and the global warming potential of these substitutes. The atmospheric lifetime of CH3CFCl2(HCFC-141b) is approximately 50% longer than the previously accepted value. AL-056 Talukdar, R., A. Mellouki, T. Gierczak, J.B. Burkholder, S.A. McKeen, and A.R. RAVISHANKARA. Atmospheric lifetime of CHF2Br, a proposed substitute for halons. Science 252:693-695 (1991). The rate coefficients, k\, for the reaction of OH with CHF2Br have been measured using pulsed photolysis and discharge flow techniques at temperatures (T) between 233 and 432 K to be ki = (7.4 ± 1.6) x 10-13 exp[-(1300 ± 100)/7] cubic centimeters per molecule per second. The ultraviolet absorption cross sections, CT, of this molecule between 190 and 280 nanometers were measured at 296 K. The Jk 1 and a values were used in a one-dimensional model to obtain an atmospheric lifetime of approximately 7 years for CHFzBr. This lifetime is shorter by approximately factors of 10 and 2 than those for CF3Br and CF2ClBr, respectively. The ozone depletion potentials of the three compounds will reflect these lifetimes. AL-057 Trainer, M., M.P. Buhr, CM. Curran, F.C. FEHSENFELD, E.Y. Hsie, S.C. LIU, R.B. NORTON, D.D. PARRISH, and E.J. Williams. Observations and modeling of the reactive nitrogen photochemistry at a rural site. Journal of Geophysical Research 96(D2):3045- 3063 (1991). Ambient concentrations of key trace gases were measured concurrently at a rural site in the eastern United States during the summer of 1986. The extensive data set allows the evaluation of certain aspects of photochemical oxidant models. A 4-day high-pressure period is chosen for a comparison of the model predictions with observations. The emphasis of this analysis is on the discussion of the photochemistry of the reactive nitrogen species and their role in shaping the ozone budget. Observations of the NO2/NO ratio provide an estimate of the peroxy radical concentration at the site. The peroxy radical concentration so derived indicates a significant in-situ O3 formation which is in accordance with the observed diurnal variation of O3. Isoprene, a natural hydrocarbon, is shown to be much more important than the anthropogenic hydrocarbons in this O3 formation. At this rural site NO, NO 2, HNO3, and peroxyacetyl nitrate (PAN) account for 85% or more of NOy (the sum of the reactive nitrogen species). The diumal cycle of the reactive nitrogen species and their partitioning is determined by transport and photochemical conversion. At night in the boundary layer defined by a low-level inversion, NO* is the major NOy species at this site. Nitric acid and PAN are suppressed by dry deposition and, in the case of PAN, thermal decomposition. During the daytime the NO, contribution of NOy decreases first as higher concentrations of HNO3 and PAN are mixed downward upon the breakup of the nocturnal inversion followed by NO x conversion to other NOy species in photochemical reactions. AL-058 TUCK, A.F. Summary of atmospheric chemistry observations from the Antarctic and Arctic aircraft campaigns. Ihs International Society for Optical Engineering 1491:252-272 (1991). In the case 1.2 of the high altitude ER-2 observations of CIO, O3, H2O, N2O, NOy, CFCI3, CF2CI2, condensation nuclei, wind, temperature and pressure are presented as averages of all flights. The data are displayed as vertical profiles over the airfields (Punta Arenas at 53°S, 71°W; Stavanger at 59°N, 6°E) and within the vortices at approximately 72°S and 78°N respectively. Horizontal profiles within isentropic layers are also shown as averages. In the case of the DC-8, some examples illustrating important observations are given. The periods of the missions were 17 August - 29 September 1987 and 3 January - 20 February 1989. AL-059 Tumipseed, A.A., G.L. Vaghjiani, T. Gierczak, J.E. Thompson, and A.R. RAVISHANKARA. The photochemistry of ozone at 193 and 222 nm. Journal of Chemical Physics 95(5):3244-3251 (1991). The quantum yields for the formation of O(iD) and 0(3P) from the photolysis of ozone have been measured at 222 and 193 nm. The quantum yield for 0(3P) was observed to be (iD) = 0.87 ± 0.04. This measurement is consistent with other studies of O3 photolysis within the Hartley band which indicate that a significant portion (5-15%) of the products are formed in the ground state. At 193 nm the quantum yield for the production of excited state O(iD) atoms is (1D) = 0.46 ± 0.29, which is significantly less than what is observed during photolysis within the lower energy Hartley 12 band. The quantum yield for 0(3P) atoms at 193 nm was found to be 0.57 ±0.14. We have also observed that the quantum yield for O atoms [0(iD) + O(JP)] is greater than unity [O(O) = 1.20 ± 0.15] at 193 nm indicating the presence of a channel which produces three 0(3P) atoms. Qj(biE) has also been detected and quantified, ^fc'Z) = 0.50 ± 0.38, from O3 photolysis at 193 nm. These measurements suggest that 0(1 D) and O ■£)> 1 X) are co-produced. AL-060 Tyndall, G.S., and A.R. RAVISHANKARA. Atmospheric oxidation of reduced sulfur species. International Journal of Chemical Kineiics 23: 483-527 (1991). The kinetics of elementary gas phase reactions involved in the oxidation of reduced sulfur species, H2S, CS2, OCS, CH3SH, CH3SCH3, and CH3SSCH3 to SO2 (or other products) are reviewed. The reactions with OH and NO 3 which are the processes that initiate the degradation of the above compounds have been evaluated. Reactions of key intermediates, HS, HSO, CH 3S, and CH 3SO, are discussed. Whenever possible, recommendations for the rate coefficients are made and the need for further work indicated. The review has been carried out with the atmospheric chemistry in mind by looking at the laboratory based kinetics data. This review also provides information that will help model the Earth's sulfur cycle. AL-061 Vaghjiani, G.L., and A.R. RAVISHANKARA. New measurement of the rate coefficient for the reaction of OH with methane. Nature 350(63 17):406-409 (1991). Methane is an important greenhouse gas, whose concentration in the troposphere is steadily increasing. To estimate the flux of methane into the atmosphere and its atmospheric lifetime, its rate of removal needs to be accurately determined. The main loss process for atmospheric methane is the reaction with the hydroxyl radical OH. We have measured the rate coefficient for this reaction in carefully controlled experiments and found it to be smaller than currently accepted values. Our results indicate a longer CH4 lifetime (by -25%) and a correspondingly smaller flux (by -100 Tg CH4 yr-i) than previously calculated. AL-062 VANZANDT, T.E., and G.D. Nastrom. Comparison of model doppler-shifted gravity-wave spectra with spectra observed over very flat terrain. AMS Eighth Conference on Atmospheric and Oceanic Waves and Stability, Boulder, CO (1991). No Abstract. AL-063 VANZANDT, T.E., G.D. Nastrom, and J.L. Green. Frequency spectra of vertical velocity from Flatland VHF radar data. Journal of Geophysical Research 96:2845-2855 (1991). The vertical wind velocity over very flat terrain was observed every 153 s in the troposphere and lower stratosphere by the Flatland radar, near Champaign-Urbana, Illinois. Several hundred frequency spectra were calculated from all accepted 6-hour time series from March through May 1987. By stratifying the spectra in various ways we find the following: (1) The spectra were independent of altitude within the troposphere or lower stratosphere, but the spectra in the two regions differed in amplitude and frequency; (2) At a given altitude the spectra were independent of the wind shear du/dz, the buoyancy frequency N, and the maximum wind speed below 16 km; (3) The change of spectral shape and amplitude with increasing background wind speed u was much less than at stations near mountains. The variance of the spectra, equal to twice the vertical kinetic energy per unit masse, roughly doubled as u increased by 10 m s -l: (4) The spectra were consistent with being due to a spectrum of gravity waves, as indicated by the sharp drop in spectral amplitude near N at small u and by the fact that the observed change of shape with increasing u was quite consistent with the change of shape of model Doppler-shifted gravity wave spectra; (5) The results of comparison between the observed and model spectra are consistent with an intrinsic gravity wave spectrum that is invariant with u, du/dz, etc., contrary to expectations from gravity wave theory; (6) The results are insensitive to the azimuthal distribution of gravity wave energy, as long as the distribution is roughly symmetrical relative to the mean flow; (7) The resulting characteristic horizontal phase velocity c« of the intrinsic frequency spectrum was about 6 m s -1 in both the troposphere and the stratosphere. The corresponding characteristic vertical wavelengths were about 3300 and 1800 m, respectively, consistent with previous estimates. AL-064 Wang, N.S., and CJ. HOWARD. Kinetics of the reactions of HS and HSO with O3. Ui£ Journal of. Physical Chemistry 94(25):8787-8794 (1990). 13 The kinetics of the reactions of HS and HSO with O3 have been studied in a discharge flow tube system coupled to a laser magnetic resonance spectrometer: HS + O3 -> HSO + O2 (1); HSO + O3 -> products (2). Measurements were made at low pressures (1-2.2 Torr) and temperatures between 296 and 431 K. The Arrhenius equation for reaction 1 is *i = (1.1 ± 0.2) x 10-n exp((-280 ± 50)/7") cm3 molecule-l s-l. Our result for k\ at room temperature is somewhat higher than the results of two previous studies. Reaction 2 has more than one channel: HSO + O3 -* HS + 2O2 (2a), which regenerates HS, and one or more competing processes that oxidize HSO further: HSO + O3 — » products (2a). The complex reaction mechanism required computer simulations to obtain: *2» = (7.0 ± 2.0) x 10-14 at 297 K, (9.0 ± 3.0) x 10-14 at 377 K, and (1.0 ± 0.3) x 10-13 cm 3 molecule-l s-l at 404 K. The room temperature k^ value is in reasonable agreement with an earlier study, k^ was measured directly to be (3.5 ± 1.5 ) x 10-14 cm3 molecule-l s-l at 296 K and (8.6 ± 3.5) x 10-14 cm3 molecule-l s-l at 404 K. The deuterium isotope effect on reactions 1 and 2a was also investigated, A(DS + O3 — > DSO + O2) = (4.0 ± 0.8) x 10-12 cm3 molecule-l s-l and *(DSO + O3 ->DS + 20 2) = (3.0 ± 1.0) x 10-14 cm3 molecule-i s-l both at 300 K. The application of our results to the oxidation mechanism of H2S in the atmosphere is discussed. AL-065 WARNOCK, J.M., T.E. VANZANDT, W.L. CLARK, S.J. Franke, Han Kim, and G.D. Nastrom. Measurement of synoptic-scale vertical velocities by two nearby VHF doppler radars in very flat terrain. The Second Symposium on Tropospheric Profiling: Needs and Technologies, Boulder, CO (1991). No Abstract. AL-066 Warren, R.F., T. Gierczak, and A.R. RAVISHANKARA. A study of O(iD) reactions with CFC substitutes. Chemical Physics Letters 183(5):403-409 (1991). The rate coefficients for the removal of O(iD) by reaction with the following nine CFC substitutes have been measured using time-resolved vacuum UV atomic resonance fluorescence detection of 0(3P): CHF2C1 (HCFC 22), CF3CHCI2 (HCFC 123), CF3CHCIF (HCFC 124), CF3CHF2 (HFC 125), CF3CH 2C1 (HCFC 133a), CF3CH2F (HFC 134a), CH3CFCI2 (HCFC 141b), CH3CF2C1 (HCFC 142b), and CH3CHF2 (HFC 152a). The branching ratios for the quenching of O(iD) to 0(3P) by the above molecules were determined by measuring the 0(3P) yields in the presence of the HCFC/HFCs relative to that in the presence of N2. By difference, the rate coefficients for the chemical reaction of O(iD) with the HCFC/HFCs were calculated. AL-067 Williams, E.J., and F.C. FEHSENFELD. Measurement of soil nitrogen oxide emissions at three North American ecosystems. Journal of Geophysical Research 96:1033-1042 (1991). Results from measurements of emission of nitrogen oxides from soils at three North American ecosystems are presented. These measurements were conducted during the summer and fall of 1988 at (1) a grassland site near Nunn, Colorado, (2) a coastal marine environment at North Inlet, South Carolina and (3) a deciduous forest near Oak Ridge, Tennessee. Emission of NO was highest from the grassland soil (mean: 10.0 ng N m-2s-i), intermediate at the forest area (mean: 0.28 ng N m-2 s-l) and lowest at the coastal site (mean: 0.034 ng N m-2 s-l). A comparison of the results from the present study with previous measurements indicates that NOx(NO + N02) emission from grasslands and temperate forests are similar within each ecosystem independent of location. This suggests that simple approaches may be used to estimate soil emissions over wide areas. AL-068 Wilson, J., D. CARTER, W. ECKLUND, K. GAGE, M. Spowart, and H. Cole. First test of a ship-board wind profiler. Second Symposium on Tropospheric Profiling: Needs and Technologies, Boulder, CO (1991). No Abstract. 14 AIR RESOURCES LABORATORY AR-001 Alkezweeny, A., J. Stith, and J.K.S. CHING. Observations of transport of trace gases by vigorous convective clouds. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991 . American Meteorological Society, Boston, 224-227 (1991). Extended abstract. AR-002 ACKERMANN, G.R. Data base management strategies for large field studies. Proceedings, 84th Annual Meeting of the Air & Waste Management Association, Vancouver, B.C., June 16-25, 1991. Air & Waste Management Association, Pittsburgh, A&WMA 91-71.1 (1991). The joint SJVAQS and AUSPEX field study involved many and varied volumes of data collected over a large area using very diverse collection platforms. Management of the resulting data base produces its own particular set of challenges. Many "views" or perspectives can be used in organizing and presenting the various aspects of the data base. The temporal view of the data base is arguably the most important. The near-real-time collection of information was very important to the conduct of this study. However, near-real-time techniques do not lend themselves well to the analysis and archival stages that follow the actual field phase of the study. This means that the data base, and the tools used to work with it, undergo substantive changes with time. These changes, and several other views of the data base are discussed in this paper along with the various techniques and tools used to facilitate the goal of a very good and useful data base that will serve the scientific community for many years to come. AR-003 ANGELL, J.K. Changes in tropospheric and stratospheric global temperatures, 1958-1988. In Greenhouse-Gas-Induced Climatic Change: A Critical Appraisal of Simulations and Observations, M.E. Schlesinger (Ed.), Elsevier Science Publishers B.V., Amsterdam, 231-247(1991). Based on a network of 63 radiosonde stations distributed fairly evenly around the world, the global tropospheric temperature in 1988 was the maximum observed since the beginning of the record in 1958, .02°C warmer than 1983, .06°C warmer than 1987, and about .16°C warmer than 1980 and 1981. The global tropospheric temperature is indicated to have increased by a significant 0.2°C between 1958-72 and 1974-88, but with most of the warming in the Southern Hemisphere and the north temperate zone even cooling slightly. Between these two intervals there was cooling in all climatic zones in the tropopause layer, the cooling of 0.2-0. 3°C significant in both hemispheres. The global low stratosphere cooled by more than 1.5°C following the 0.5 °C warming occasioned by the El Chichon volcanic eruption, with most of the cooling in the Southern Hemisphere and in particular in the south polar zone (Antarctic "ozone hole" phenomenon). Emphasized is the strong influence of El Nino on global tropospheric temperatures about 2 seasons later, and because of the El Nino in 1987, the need for caution in relating the record warmth of 1988 to any greenhouse effect. Discussed is the extent to which these tropospheric and stratospheric temperature changes support the presumption that a greenhouse effect is already being observed. AR-004 AUBLE, D.L., and T.P. MEYERS. An open path, fast response infrared H20 and C02 gas analyzer. Preprints, Seventh Symposium on Meteorological Observations and Instrumentation and Special Sessions on Laser Atmospheric Studies, New Orleans, LA, January 14- 18, 1991. American Meteorological Society, Boston, 30-33 (1991). Extended abstract. AR-005 BALDOCCHI, D.D., R.J. Luxmoore, and J.L. Hatfield. Discerning the forest from the trees: an essay on scaling canopy stomatal conductance. Agricultural and Forest Meteorology 54:197-226 (1991). Stomata are major conduits for the diffusion of many trace gases between leaves and the atmosphere. The role of the stomata in controlling gas exchange between the terrestrial biosphere and the atmosphere at the landscape, meso- and global scales has only recently been appreciated. Further advances in modeling trace gas exchange will depend on our ability to provide realistic information on stomatal mechanics at the sub-grid scale of landscape and meso scale models; in other words, information is needed at the canopy scale. This paper describes two approaches for estimating canopy stomatal conductance. These are the 'bottom-up' and 'top-down' scaling methods. The 15 bottom-up method entails computing canopy stomatal conductance by integrating the response of individual leaves to controlling biotic and abiotic factors, which are determined by the micrometeorology of the canopy. The top-down approach entails inverting a descriptive stand- level, trace gas exchange model to estimate canopy stomatal conductance. The model is driven with abiotic variables measured at a reference point above the canopy. The strengths and weaknesses of these two approaches are discussed, and recommendations for future research are presented. AR-006 BALDOCCHI, D.D., and T.P. MEYERS. Evaporation from the floor of a deciduous forest. Preprint Volume, 20th Conference on Agricultural and Forest Meteorology, Salt Lake City, UT, September 10-13, 1991. American Meteorological Society, Boston, 63-65 (1991). No abstract. AR-007 BALDOCCHI, D.D., and T.P. MEYERS. Trace gas exchange above the floor of a deciduous forest I. Evaporation and COj efflux. Journal of Geophysical Research 96 (D4): 727 1-7285 (1991). The eddy correlation method has great potential for directly measuring trace gas fluxes at the floor of a forest canopy, but a thorough validation study has not been yet conducted. Another appeal of the eddy correlation method is its ability to study processes that regulate and modulate gas exchange between the soil/litter complex and the atmosphere that cannot be probed with chambers. In this paper we report on eddy correlation measurements of water vapor, sensible heat, and carbon dioxide exchange that were made at the floor of a deciduous forest. The validity of the eddy correlation method to measure the emission of water vapor and CO^ from a deciduous forest floor is demonstrated by our ability to close the surface energy budget during periods that meet the requirements of the technique. Water vapor fluxes from a dry forest floor are strongly influenced by large-scale turbulent events that penetrate deep into the canopy. The frequency of these turbulent events prevents equilibrium evaporation rates from being achieved because the dynamic time constant for water vapor exchange is longer. Consequently, maximal evaporation rates are capped to rates defined by the product of the driving potential of the atmosphere and the surface conductance. On the other hand, evaporation from a wet forest floor proceeds at rates reaching or exceeding equilibrium evaporation and are highly correlated with static pressure fluctuations. COj efflux rates are governed by litter and soil temperature, as expected. But we also find a significant correlation between static pressure fluctuations and soil/litter CO, exchange rates. AR-008 Barchet, W.R., R.L. DENNIS, and S.K. Seilkop. Evaluation of RADM using surface data from the Eulerian model evaluation field study. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14- 18, 1991. American Meteorological Society, Boston, 63-66 (1991). Extended abstract. AR-009 Bardwell, C.A., J.R. Maben, J.A. Hurt, W.C. Keene, J.N. Galloway, J.F. BOATMAN, and D.L. WELLMAN. A technique using high-flow, dichotomous filter packs for measuring major atmospheric chemical constituents. Global Biogeochemical Cycles 4(2): 151- 163 (1990). We developed a high-resolution technique to measure major reactive trace gases and the chemical composition of size-segregated aerosols in the troposphere as part of the 1988 Global Change Expedition/Coordinated Air-Sea Experiment/Western Atlantic Ocean Experiment. We sampled air over the western North Atlantic Ocean from the NOAA King Air research aircraft and NOAA ship Mt. Mitchell during July. Our system used filter packs containing an upstream, 90-mm quartz filter to collect particles followed by two 90-mm rayon filters impregnated with 10% K2CO3-10% glycerol to collect alkaline reactive gases. Paired filter packs were exposed when the aircraft sampled the boundary layer. An upstream cyclone with a 50% aerodynamic cut radius of approximately 0.4 juti removed large particles from one of the filter-pack inlets. Air was sampled at an average rate of 0. 12 m3 STP min ' for the fine filter packs and 0.26 m3 STP min ' for the total over intervals of 45 min to 90 min. Particulate-phase concentrations of major anions (SO,2 , CH3 S03", NO,, CI") and organic species (HCOO, [HCOO and HCOOH] and CH3COO and CH3COOH) were measured by gradient elution ion chromatography; base cations (Ca2\ Mg2*, Na + , K+) by atomic-absorption spectroscopy; NH/ by automated colorimetry; and H+ by glass electrode. We quantified S02, HN03, and HC1 using two isocratic ion chromatography methods. This technique provided higher signal-to-noise ratios allowing increased temporal and spatial resolution, pH determination of particulate-phase filter extracts, and measurement of HC1 on gas- phase filters. 16 AR-010 BINKOWSKI, F.S., J.S. Chang, R.L. DENNIS, S. Reynolds, P.J. Samson, and J.D. Shannon. Regional Acid Deposition Modeling. Acidic Deposition: State of Science and Technology Report 3, Volume I, Emissions, Atmospheric Processes and Deposition. National Acid Precipitation Assessment Program, Washington, DC, 3-1 - 3-59 (1990). No abstract. AR-011 BINKOWSKI, F.S., J.N. McHenry, and J.S. Chang. Estimation of the contribution of Canadian versus United States emissions to sulfur deposition. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 54-57 (1991). Extended abstract. AR-012 BOATMAN, J.F., W.C. Keene, M. Luria, J.D. Ray, C.A. Bardwell, K. Gorzelska, M. Fennell, D.R. Hastie, A. A. P. Pszenny, and D. Whelpdale. An intercomparison of the chemical and meteorological data generated from aircraft and shipboard sampling during GCE/CASE/WATOX. NOAATM ERL ARL-186 (PB91 129098), 26 pp. (1990). We compared 16 selected chemical and meteorological parameters from the NOAA ship Mt. Mitchell and the NOAA King Air research aircraft during the GCE/CASE/WATOX experiment. The aircraft made 8 research flights during July, 1988 in coordination with the ship. The first four were off the U.S. East Coast near Newport News, VA and the last four were near the island of Bermuda. We used only the low altitude portions of the aircraft flights in our ship to aircraft intercomparisons. Generally, the aircraft and shipboard measurements were within expected accuracy limits. Selected exceptions for individual species and days are noted and discussed in the text. AR-013 BRIGGS, G.A., R.S. Thompson, and W.H. SNYDER. Dense gas removal from a valley by crosswinds. Journal of Hazardous Materials 24:1-38 (1990). Wind tunnel experiments were made to determine how rapidly dense gas trapped in a topographic depression could be removed by an entraining crosswind. The two-dimensional outflow volume flux, v0, was assumed equal to the inflow rate during 92 steady-state experiments with CO^ continuously supplied into the bottom of two-dimensional, V-shaped valleys. As predicted by theory, at large Reynolds numbers it was found that v„oeUVgi\ where U, is the speed just above the dense gas pool and &' is gravity times the relative density difference. The width of the pool, w, does not affect v„ when the primary Froude number .<. 1, except at low Reynolds numbers; in this case the data suggest v0oc (U.wk)"2 as an asymptote, where k is the molecular diffusivity. A universal relationship is suggested for v,, bridging these two asymptotes. Transient experiments were conducted by filling a valley with dense gas, turning it off, then quickly removing a sliding cover; v0 was measured as a function of time with an array of samplers downwind. These experiments essentially confirmed predictions based on the steady-state results, even when SF6 was substituted for COz. Insertion of a flat floor into the valley had only minor effects on v„(t) until the pool level subsided almost to the floor level. Substantial changes in the removal process were observed for the few tests run at Froude numbers exceeding unity. AR-014 BULLOCK, O.R., Jr. The effect of sub-grid-scale rainfall analysis on sulfate wet deposition estimates in the REgional Lagrangian Model of Air Pollution (RELMAP). Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 81-84 (1991). Extended abstract. AR-015 Burns, D.J., S.G. PERRY, and A.J. Cimorelli. An advanced screening model for complex terrain applications. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991 . American Meteorological Society, Boston, 97-100 (1991). Extended abstract. 17 AR-016 Byun, D.W., and F.S. BINKOWSKI. Sensitivity of RADM to point source emissions processing. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 70-73 (1991). Extended abstract. AR-017 Chang, J.S., P.B. Middleton, W.R. Stockwell, C.J. Walcek, J.E. PLEJM, H.H. Lansford, F.S. BINKOWSKI, S. Madronich, N.L. Seaman, and D.R. Stauffer. The Regional Acid Deposition Model and Engineering Model. Acidic Deposition: State of Science and Technology Report 4, Volume I, Emissions, Atmospheric Processes and Deposition. National Acid Precipitation Assessment Program, Washington, DC, 4-1 - 4-130 (1990). No abstract. AR-018 CHING, J.K.S., and N.E. Bowne. AcidMODES, A major field study to evaluate regional scale air pollution models. Proceedings, Remote Sensing of Atmospheric Chemistry Conference, Orlando, FL, April 1-3, 1991. Society of Photo-Optical Instrumentation Engineers, Bellingham, WA, Volume 1491:360-370(1991). Regional scale, Eulerian framework air quality simulation models are currently being evaluated using pollutant and meteorological measurements from special surface networks and airborne platforms. An evaluation protocol for such models using this database has been developed and adopted by the National Acid Precipitation Assessment Program; it includes "Operational" and "Diagnostic" components. This paper focuses on the diagnostic evaluation of the Regional Acid Deposition Model (RADM), using aircraft measurements from the Acid Model Operational Diagnostic Evaluation Study (AcidMODES) program under sponsorship of the United States Environmental Protection Agency (USEPA). RADM's ability to resolve horizontal patterns and gradients as well as the vertical structure of primary and secondary acidic pollutant species in the mixed layer over the major source region for sulfur and nitrogen emissions is an essential diagnostic test and is demonstrated. The potential roles of remote sensing in the evaluation of the regional models are suggested. AR-019 CHING, J.K.S., J. Chang, C. Spicer, and E. Schaller. Investigation of RADM performance using aircraft measurements. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 42-45 (1991). Extended abstract. AR-020 Chu, S.-H., and D.C. DOLL. Summer blocking highs and regional ozone episodes. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 274-277(1991). Extended abstract. AR-021 CLARK, T.L., and R.D. Cohn. Performances of Lagrangian and Eulerian transport and diffusion models across continental scales. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 89-92 (1991). Extended abstract. AR-022 Coats, C.J., and K.L. SCHERE. Wind field development for the EPA Regional Oxidant Model. Proceedings, 84th Annual Meeting of the Air & Waste Management Association, Vancouver, B.C., Canada, June 16-25, 1991. Air & Waste Management Association, Pittsburgh, A&WMA 91-67.7 (1991). No abstract. IX AR-023 Coats, W.G., J.T. Snow, and C.B. BAKER. A comparative study of the dynamic performance of bivanes. Preprints, Seventh Symposium on Meteorological Observations and Instrumentation and Special Sessions on Laser Atmospheric Studies, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 86-92 (1991). Extended abstract. AR-024 Conklin, P.S., K.R. Knoerr, and C.B. BAKER. A wind tunnel and field comparison of two static pressure probes. Preprints, Seventh Symposium on Meteorological Observations and Instrumentation and Special Sessions on Laser Atmospheric Studies, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 92-96 (1991). Extended abstract. AR-025 COOTER, E.J., S.K. LEDUC, L. TRUPPI, and D.R. Block. Climate data and analysis for the New England Forest Health Monitoring Project (NEFHM/EMAP Forests). Preprints, Seventh Conference on Applied Climatology, Salt Lake City, UT, September 10-13, 1991. American Meteorological Society, Boston, 57-62 (1991). Extended abstract. AR-026 CRAWFORD, T.L., and R.T. McMILLEN. Direct measurement of CO^ exchange to the ocean using an airborne eddy-correlation system. Preprints, Seventh Symposium on Meteorological Observations and Instrumentation and Special Sessions on Laser Atmospheric Studies, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 42-45 (1991). Extended abstract. AR-027 CRAWFORD, T.L., R.T. McMILLEN, and R.J. Dobosy. Description of a "generic" mobile flux platform using a small airplane and a pontoon boat. Preprints, Seventh Symposium on Meteorological Observations and Instrumentation and Special Sessions on Laser Atmospheric Studies, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 37-41 (1991). Extended abstract. AR-028 Dayan, U., J. HEFFTER, J. MILLER, and G. GUTMAN. Dust intrusion events into the Mediterranean Basin. Journal of Applied Meteorology 30(8):1 185-1 199 (1991). In this study seven dust intrusion events were identified and analyzed in the central and eastern part of the Mediterranean Sea beginning August 1988 and ending September 1989. In order to locate their sources, characterize their mode, and determine atmospheric transport levels, air flow back trajectories were calculated using the BAT Model (Heffter, 1983) for two layers (300-2000 m; 1500-3000 m) in conjunction with the synoptic situations prevailing during these dust outbreak events. Aerosol mass loading and horizontal visibility were derived for each of these seven cases from optical thickness values as analyzed by visible and near infrared radiances measured with the NOAA-9 and NOAA-1 1 satellite borne radiometers. Optical thickness is displayed in composite weekly charts over the Mediterranean. The analysis has shown that transport of Saharan dust occurring in the central part of the Mediterranean are usually rather intensive in their atmospheric mass loading capacity and take place in deeper atmospheric layers for a longer duration (approximately 2-4 days) than eastern Mediterranean dust events. The eastern transport usually originates from the Arabian Desert for short periods (approximately 1 day) and is restricted to a rather shallow atmospheric transport layer featured by low optical depth values. AR-029 DENNIS, R.L., W.R. Barchet, T.L. CLARK, and S.K. Seilkop. Evaluation of Regional Acid Deposition Models, Part 1. Acidic Deposition: State of Science and Technology Report 5, Volume I, Emissions, Atmospheric Processes and Deposition. National Acid Precipitation Assessment Program, Washington DC (1990). No abstract. 19 AR- 030 DENNIS, R.L., F.S. BINKOWSKI, T.L. CLARK, J.N. McHenry, S.J. Reynolds, and S.K. Seilkop. Selected Applications of the Regional Acid Deposition Model and Engineering Model, Part 2, Appendix 5F. Acidic Deposition: State of Science and Technology Report 5, Volume I, Emissions, Atmospheric Processes and Deposition. National Acid Precipitation Assessment Program, Washington, DC (1990). No abstract. AR-031 DiChristofaro, D.C., and J.S. TOUMA. Development and sensitivity analysis of the shoreline dispersion model (SDM). Preprints, 19th International Technical Meeting on Air Pollution Modeling and its Applications, Volume I, Crete, Greece, September 29-October 4, 1991. NATO/CCMS, Brussels, Belgium, 153-160(1991). No abstract. AR-032 DICKE, J.L. Overview of proposed changes to the modeling guideline and special topics of complex terrain, roadway intersections and stability classifications. Proceedings, Fifth Conference on Air Quality Modeling, Washington, DC, March 1991. U.S. Environmental Protection Agency, Research Triangle Park, NC, 37 pp. (1991). No abstract. AR-033 Dobosy, R.J., and T.L. CRAWFORD. Developments in turbulence measurement by pressure sphere. Preprints, Seventh Symposium on Meteorological Observations and Instrumentation and Special Sessions on Laser Atmospheric Studies, New Orleans, LA, January 14- 18, 1991. American Meteorological Society, Boston, 151-155 (1991). Extended abstract. AR-034 DONNELLY, R.F. Temporal variations of solar UV, EUV, and X-ray fluxes, sunspot number, and F10. Solar-Terrestrial Predictions: Workshop Proceedings, Leura, Australia, October 16-20, 1989. Volume 1, Working Group Reports, Invited Papers, and Contributed Solar Papers, 381-385 (1990). Predictions of future values of sunspot number (R) and the Ottawa solar 10.7 cm flux (F10) are made as surrogate estimators of the solar radiative fluxes that heat, photodissociate and ionize the terrestrial atmosphere because only R and F10 have long enough time series to apply lime series analyses for developing predictions. Data sets of solar UV, EUV and X-ray fluxes have been too short in duration to be used to develop predictions of solar cycle variations. Systematic differences in the temporal variations of solar UV, EUV and X-ray measurements relative to the classical solar indices are discussed for the shape of the solar cycle, intermediate-term variations (4-11 months), and short-term variations (days, weeks). AR-035 DRAXLER, R.R., R. Dietz, R.J. Lagomarsino, and G. START. Across North America Tracer Experiment (ANATEX): Sampling and analysis. Atmospheric Environment 25A(12):2815-1836 (1991). Between 5 January 1987 and 29 March 1987, there were 33 releases of different tracers from each of two sites: Glasgow, MT and St. Cloud, MN. The perfluorocarbon tracers were routinely released in a 3-h period every 2.5 days, alternating between daytime and nighttime tracer releases. Ground-level air samples of 24-h duration were taken at 77 sites mostly located near rawinsonde stations east of 105 °W and between 26°N and 55°N. Weekly air samples were taken at 12 remote sites between San Diego, CA and Pt. Barrow, AK and between Norway and the Canary Islands. Short-term 6-h samples were collected at ground level and 200 m AGL along an arc of five towers between Tulsa, OK and Green Bay, WI. Aircraft sampling within several hundred kilometers of both tracer release sites was used to establish the initial tracer path. Experimental design required improved sampler performance, new tracers with lower atmospheric backgrounds, and improvements in analytic precision. The advances to the perfluorocarbon tracer system are discussed in detail. Results from the tracer sampling showed that the average and peak concentrations measured over the daily ground-level sampling network were consistent with what would be calculated using mass conservative approaches. However, ground-level samples from individual tracer patterns showed considerable complexity due to vertical stability or the interaction of the tracer plumes with low pressure and frontal systems. These systems could pass right through the tracer plume without appreciable effect. Aircraft tracer measurements are used to 20 confirm the initial tracer trajectory when the narrow plume may miss the coarser spaced ground-level sampling network. Tower tracer measurements showed a more complex temporal structure than evident from the longer duration ground-level sampling sites. Few above background plume measurements were evident in the more distant remote sampling network due to larger than expected uncertainties in the ambient background concentrations. AR-036 EDER, B.K., and R.L. DENNIS. On the use of scavenging ratios for the inference of surface-level concentrations and subsequent dry deposition of CA2+, Mg2*, Na+ and K+. Water, Air, and Soil Pollution 52:197-216 (1990). An inference technique is developed that allows estimation of the annual and monthly dry deposition of CA2 + , Mg2*, Na+ and K+. Conceptually, this technique is based on the premise that precipitation efficiently scavenges aerosols, resulting in a strong correlation between concentrations within precipitation and the surface-level air. Empirically, it is based on the linear relationship exhibited between the measured surface-level air and precipitation concentrations at 23 stations in Ontario, Canada, for the period 1983-1985. Correlations ranged from 0.513 for K+ to 0.946 for Mg2*. Because of the stochastic nature of such an approach, the assumptions inherent to the concept of scavenging ratios, and therefore this inference technique, must be carefully considered. Under such considerations, annual and monthly dry deposition of alkaline aerosols can be estimated at many locations across North America where precipitation concentrations are routinely measured. AR-037 Eklund, B., S. Smith, J.F. Durham, and J.S. TOUMA. Estimation of emissions, ambient air concentrations, and health effects from air stripping of contaminated water. Proceedings, 84th Annual Meeting of the Air & Waste Management Association, Vancouver, B.C. Canada, June 16-25, 1991. Air & Waste Management Association, Pittsburgh, A&WMA 91-13.3 (1991). No abstract. AR-038 ELLIOTT, W.P., J.K. ANGELL, and K.W. Thoning. Relation of atmospheric COj to tropical sea and air temperatures and precipitation. Tellus 43(B):144-155 (1991). Associations between the season-to-season changes in CO, concentration and the sea-surface temperature in the eastern equatorial Pacific, the tropospheric air temperature, and the precipitation in the tropics are explored. The C02 records at Mauna Loa and the South Pole from Scripps Institution of Oceanography and the GMCC/NOAA program, as well as the GMCC records at Barrow, Alaska and American Samoa were used after the annual cycle and the growth due to fossil fuel emission had been removed. We find that the correlation between C02 changes and each of the other variables changes with time. In particular, the period from about 1968 to about 1978 was the period of highest correlation, which was also the period when the climate variables were best correlated with each other. The air temperature and the precipitation were as well correlated with COj changes as was SST. Also there are individual seasons when the CO, changes are much better correlated with the climate variables than at other seasons. Furthermore, El Nino events, while the source of the largest signal in the C02 record, are by no means the same from one event to the next. We take these results as further confirmation that the apparent effect of SST on the C02 record comes less from changes in the equatorial eastern Pacific Ocean than from climate changes throughout the globe. Climate effects on the terrestrial biosphere seem a likely source of much of the interannual variation in atmospheric co2. AR-039 ELLIOTT, W.P., M.E. SMITH, and J.K. ANGELL. Monitoring tropospheric water vapor changes using radiosonde data. In Greenhouse-Gas-Induced Climatic Change: A Critical Appraisal of Simulations and Observations, M.E. Schlesinger (Ed.), Elsevier Science Publishers B.V., Amsterdam, 311-326 (1991). Significant increases in the water vapor content of the troposphere are expected to accompany temperature increases due to rising concentrations of the greenhouse gases. Thus it is important to follow changes in water vapor over time. There are a number of difficulties in developing a homogeneous data set, however, because of changes in radiosonde instrumentation and reporting practices. We report here on preliminary attempts to establish indices of water vapor which can be monitored. The precipitable water between the surface and 500 mb is the first candidate. We describe our method for calculating this quantity from radiosonde data for a network very similar to the network Angell uses for detecting temperature trends (see Angell, 1990). Preliminary results suggest that the noise level is low enough to detect trends in water vapor at the individual stations. While a slight increase in global water vapor is hinted at in the data, and the data suggest there may have been a net transfer of water from the Southern Hemisphere to the Northern, these conclusions are tentative. We also discuss the future course of this investigation. 21 AR-040 Ennis, G., and H. Sievering. Vertical profile of elemental concentrations in aerosol particles in the Bermuda area during GCE/CASE/WATOX. Global Biogeochemical Cycles 4(2):179-188 (1990). During the 1988 Global Change Expedition/Coordinated Air-Sea Experiment/Western Atlantic Ocean Experiment (GCE/CASE/ WATOX) joint effort, research was conducted to determine elemental concentrations in atmospheric aerosol particles near Bermuda, to construct a three-level (15, 150, and 2600 m ASL) vertical profile of those concentrations, and to ascertain the source of the particles. Samples were collected by the NOAA King Air aircraft and NOAA ship Mt. Mitchell on July 24-28, 1988. Concentration determinations were made for 16 elements through the use of an X ray fluorescence instrument designed for analysis of small-mass samples. A layering effect was found; concentrations of several elements at 150 m were more than twice their respective concentrations at 15 m and 2600 m. Enrichment factors, V/Mn ratio, and correlations between concentrations suggest a Saharan mineral source, despite air mass back trajectories that show no direct continental input for up to 10 days prior to sample collection. Estimated total mineral aerosol concentrations at 15 m, 150 m, and 2600 m are 1.5, 4.1, and 2.1 /tg m\ AR-041 ESKRIDGE, R.E., W.B. PETERSEN, and S.T. Rao. Turbulent diffusion behind vehicles: Effect of traffic speed on pollutant concentrations. Journal of the Air and Waste Management Association 41:312-317(1991). Recent theoretical and experimental investigations indicate that turbulent diffusion behind moving vehicles is influenced by the speed of the vehicle. Vertical wake induced turbulent diffusion, explicitly treated in the numerical ROADWAY model, is proportional to the square of the wind speed relative to the moving vehicle. Hence, the model predictions of turbulent mixing and pollutant concentrations on and downwind of a roadway are dependent upon the traffic speed. It is expected from theoretical concentrations that the effect of vehicle speed on pollutant concentrations will be more significant during stable atmospheric conditions, because in neutral and unstable conditions the vehicle-wake turbulence is quickly masked by the ambient turbulence. In this study, experimental data are utilized to evaluate the theoretical predictions of the effects of traffic speed upon ambient concentrations are investigated through wind tunnel experiments and field studies that used dual tracers. Consistent with predictions of the ROADWAY model, data obtained near the Long Island Expressway indicate that the influence of traffic speed on the ambient pollutant concentrations is not significant during unstable and neutral conditions. The Long Island experiment did not provide sufficient field data to assess the model predictions of the traffic speed effect during stable atmospheric conditions. AR-042 FINKELSTEIN, P.L., and L.E. TRUPPI. Spatial distribution of precipitation seasonality in the United States. Journal of Climate 4:373-385 (1991). A detailed, long term portrait of the seasonality of precipitation over the United States is developed using a 90 year climate division record. Selected decadal maps of seasonality are also presented, and their variability over time considered. Relationships between significant changes in precipitation or temperature and seasonality were sought, but not found. Model output from four global climate models (GCM) are analyzed with respect to precipitation seasonality over the same area, both for present conditions, and for a doubled COj climate. Comparison of model output to present patterns suggests that in most cases the models are doing reasonably well in matching regional details of seasonality. For the future climate, there is some agreement among models suggesting a trend toward a spring, rather than summer precipitation maximum in the midcontinental areas of the United States. AR-043 GAFFEN, D.J., T. Barnett, and W.P. ELLIOTT. Space and time scales of global tropospheric moisture. Journal of Climate 4(2): 20 pp. (1991). Radiosonde data from a global 1 18 station network are used to determine the spatial and temporal scales of variability of tropospheric water vapor. Various sources of possible error and bias in the data are analyzed. Changes in instrumentation at U.S. stations are shown to have a considerable influence on the record; information on comparable changes in other countries is not readily available. Mean monthly data are shown to be acceptable at tropical stations but not at high latitude stations, where the nonlinear dependence of saturation vapor pressure on temperature, coupled with large temperature ranges, leads to biases of up to 10% in mean monthly specific humidity. A series of three empirical orthogonal function analyses (for the tropics, North America, and the globe) of specific humidity at he surface, 850 mb, 700 mb and 500 mb levels is presented. All three show evidence of a shift in the specific humidity field in the winter of 1976/77, with generally lower values from the beginning of the record (January 1973) until the shift and higher values through the winter of 1985/86. This shift is shown to be consistent with other evidence for a change in "climate state" in about 1977. The influence of the El Nino- Southern Oscillation is evident in both the tropical and global analyses. 22 AR-044 Galloway, J.N., W.C. Keene, A.A.P. PSZENNY, D.M. Whelpdale, H. Sievering, J.T. Merrill, and J.F. BOATMAN. Sulfur in the western North Atlantic Ocean atmosphere: Results from a summer 1988 ship/aircraft experiment. Global Biogeochemical Cycles 4(4):349-365 (1990). To investigate the relative importance of anthropogenic versus marine sources of sulfur in the North Atlantic Ocean troposphere, sulfur species were measured from aircraft, ship, and island based platforms as part of the Global Change Expedition/Coordinated Air-Sea Experiment/Western Atlantic Ocean Experiment conducted during the summer of 1988. Four synoptic meteorological cases were examined: flow from highly populated North America, lightly populated North America, tropical oceanic regions, and polar oceanic regions. Literature values suggest that 2-10 /imol m2 day"1 of (CH3)2S are emitted from the ocean to the atmosphere in marine regions associated with the first three synoptic cases. Data from this experiment indicate that 36, 16, and 14 /imol m"2 day1, for the highly populated North America, lightly populated North America, and tropical oceanic regions synoptic cases, respectively, were deposited to the ocean's surface. Differences between previously estimated natural emissions and calculated deposition suggest that anthropogenic sources of sulfur contribute significantly to sulfur deposition for these cases. The sulfur deposition rate for the polar oceanic regions synoptic case was 20 /xmol m2 day"1. Given the larger range of literature values for the corresponding (CH3)2S emission rate (1-14 /*mol m2 day1), however, the relative importance of the non-marine S source is less certain in this case. AR-045 Garodz, L.J., and K.L. CLAWSON. Vortex characteristics of C5A/B, C141B and C130E aircraft applicable to ATC terminal flight operations tower fly-by data. NOAA TM ERL ARL-190, 250 pp. (1991). During the spring of 1987, the National Oceanic and Atmospheric Administration (NOAA) conducted a full-scale flight test program to investigate the vortex wake characteristics of the 3 primary U. S. Air Force (USAF) Military Airlift Command (MAC) jet transport aircraft, namely, the Lockheed C5A/B Galaxy, the C141B Starlifter, and the C130E Hercules. The test program required vortex data at low airspeeds and low altitudes to meet certain operational considerations. The tower fly-by technique was employed for vortex data acquisition purposes. The study was successful in that the objectives of the study were completely fulfilled. The Federal Aviation Administration (FAA) subsequently commissioned NOAA to reexamine the data with the objective of extending the existing knowledge of vortex behavior in terminal area flight operations. The FAA was particularly interested in the application of the data to Air Traffic Control (ATC) separation standards. The data had not previously been analyzed with this goal in mind. This report describes the results of that effort. Of significance in the reexamination of the USAF data was the length of vortex persistence even under somewhat turbulent or unstable atmospheric conditions. Although no vortex ages older than 2 minutes were observed in the anemometer data, visual observations of vortex-entrained smoke indicated that C5A/B vortices persisted for as long as 3 minutes. Correlation of the Richardson Number (Ri) with vortex persistence indicated the difficulty of using this atmospheric turbulence index as an indicator of vortex decay. The effect of the high wing configuration of all three aircraft and the T-tail configuration of two of the aircraft on trailing vortex system characteristics is also discussed. The joint SJVAQS and AUSPEX field study was designed to occur within a large geographical are in central California and involve the intense activities of several hundred personnel within a three month period. An extensive management capability was required to coordinate contractor activities over the two month measurement window. Contractors for both routine ground-based monitoring programs and for intensive days of extensive aerosol, aircraft, gaseous tracer, and upper air meteorological measurements required planning and coordinating information on a day to day basis. This paper summarizes the functions planned and implemented at the centralized field operations center (FOC) in Fresno. The staff of the FOC, under the direction of the Field Program Manager, provided coordination with individual contractor organizations, personnel operating measurement platforms, project principal investigators (Pis), addressed facility and resource problems at remote field measurement sites, provided emergency communications and logistics support. Special FOC functions included the coordinated forecast support for daily and weekly planning of intensive operations, coordination between this study and other concurrent research programs, and daily briefings of the program management and the Pis. The methods selected to implement those functions, the successes and the weaknesses of them, and recommendations for future programs are presented. AR-046 Gaynor, J.E., C.B. BAKER, and B.D. TEMPLEMAN. Fine time-scale comparisons between doppler sodar and sonic anemometer-derived winds. Preprints, Seventh Symposium on Meteorological Observations and Instrumentation and Special Sessions on Laser Atmospheric Studies, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 401-404(1991). Extended abstract. AR-047 GUNTER, R.L., and J.F. BOATMAN. Acid-MODES 1988: Summary data report aircraft measurements of selected pollution species. NOAA TM ERL ARL-189, 18 pp. (1991). 23 Cloud water samples were taken and chemical, meteorological, and aerosol measurements were made with the NOAA King Air C-90 aircraft during August and September 1988 in northeastern Pennsylvania in support of the Acid Model Operational-Diagnostic Evaluation Study (Acid-MODES). Two other aircraft were involved: Battelle Laboratory's G-l and the West German Hawker-Siddeley (HS) 125. This report lists the objectives of Acid-MODES, the instrumentation used and the data obtained with the NOAA King Air, and the King Air's data processing, data quality and data availability. AR-048 Hansen, A.D.A., R.S. ARTZ, A. A. P. PSZENNY, and R.E. Larson. Aerosol black carbon and radon as tracers for air mass origin over the Atlantic Ocean. Global Biogeochemical Cycles 4(2):189-199 (1990). We present results from the Global Change Expedition/Coordinated Air-Sea Experiment/Western Atlantic Ocean Experiment (GCE'CASE/WATOX) research cruise conducted from July to September 1988 in the North Atlantic Ocean aboard the NOAA Ship Mt. Mitchell. We examine the correlations between measurements of aerosol black carbon (BC, a tracer for combustion emissions), radon-222 (Rn, a tracer for natural emissions from land masses), and calculated isentropic back-trajectories from the ship's position during two portions of the cruise that circled the North Atlantic Ocean. The results suggest four distinct categories of origin of the sampled air mass, with trajectories connecting back to different geographical areas: case A, trajectories from inhabited land, with the air mass containing strongly correlated BC and Rn; case B, trajectories from uninhabited (far northern) land, with Rn but little BC; case C, contaminated marine air, with little Rn but moderate BC, correlated with observations of combustion sources (other ships, etc.) in the vicinity; and case D, air masses of remote marine origin, with low BC and low Rn content. The requirements of the trajectory analyses lead to an improved understanding of transport pathways across the ocean. We conclude that real-time measurements of aerosol black carbon and radon, coupled with timely meteorological analyses, can be a powerful predictor of air mass origin both retrospectively and during the course of an experiment to assist in the scheduling of other measurements. AR-049 HEFFTER, J.L., and R.R. DRAXLER. Long-range forecast trajectories of volcanic ash from Redoubt Volcano eruptions. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 24-28 (1991). Extended abstract. AR-050 HICKS, B.B. Book Review. Mechanisms and Effects of Pollutant Transfer into Forests. (H.-W. Georgii (Ed.), Kluwer Academic Publishers, Dordrecht, The Netherlands, 1989). Boundary-Layer Meteorology 53:297-301 (1990). No abstract. AR-051 HICKS, B.B. NAPAP measurement accomplishments. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 36-40 (1991). Extended abstract. AR-052 HICKS, B.B., and R.S. ARTZ. Estimating background precipitation quality from network data. Proceedings, International Conference on Acidic Deposition, Its Nature and Impacts, Glasgow, Scotland, 16-21 September, 1990, pp. (1991). Assessments of the relative merits of alternative acid rain control strategies revolve around considerations of potential benefit per unit effort and/or cost. A question that often arises concerns the changes in deposition that would follow if all industrial (or societal) emissions were eliminated, in which case precipitation chemistry would be dominated by emissions from natural sources. Estimates of the "natural background" of precipitation chemistry can be based (a) on measurements made at distant locations, (b) on reducing emissions to zero in numerical simulations, or (c) on examinations of existing data. Each alternative is flawed; (a) because of the assumption that natural emissions in one location are like those in another, (b) because no existing model contains descriptions of chemical processes involving all of the chemical species of importance, and (c) because all contemporary data records of relevance are affected by precisely the emissions we wish to reduce. Here, the third alternative is explored in detail, using event precipitation chemistry data from North America. The analysis reveals a background Ph level that varies from site to site, but always lies in the range 5.0 to 5.2. 24 AR-053 HICKS, B.B., R.R. DRAXLER, D.L. ALBRITTON, F.C. FEHSENFELD, M. Dodge, S.E. Schwartz, R.L. Tanner, J.M. Hales, T.P. MEYERS, R.J. Vong, C.I. Davidson, M.L. Wesely, T.S. BATES, S.E. Lindberg, S.C. LIU, D.A. GILLETTE, H.H. Westberg, B. Lamb, J.T. Sigmon, and S.F. Mueller. Atmospheric Processes Research and Process Model Development. Acidic Deposition: State of Science and Technology Report 2. National Acid Precipitation Assessment Program, Washington, DC, 2-1 - 2-298 (1990). No abstract. AR-054 HICKS, B.B., R.P. HOSKER, JR., T.P. MEYERS, and J.D. Womack. Dry deposition inferential measurement techniques-I. Design and tests of a prototype meteorological and chemical system for determining dry deposition. Atmospheric Environment 25 A(10):2345- 2359 (1991). A simple filterpack system and a supporting meteorological and surface-condition monitoring system have been deployed in a trial network to test methods by which dry deposition rates can be estimated on a routine basis, using average air concentration data and site- specific deposition velocities. The filterpack used in this dry deposition inferential measurement (DDIM) sampler differs from standard filterpacks by the use of a heated horizontal settling tube at the inlet. This modification is intended to protect the S02 sampling system from adverse effects associated with filter liquefaction at high humidities, while at the same time providing a simple means for eliminating large particles from the sampled air. Tests indicate that the sampler works well for S02 and for particulate species, and that HNOj concentrations are underestimated by about 25%. The DDIM approach differs from previous network measurement programs in that the data sets are designed to permit extension from observations at a subset of research sites to less intensive routine measurement sites. Hence a major goal is the definition of a suitable set of supporting data from which dry deposition rates can be inferred using air concentration data. Local vegetation characteristics are noted. At present, the additional variables that are monitored are solar radiation, wind speed, wind direction standard deviation, temperature, humidity, surface wetness, and precipitation. Observers report changes in the surrounding surface, such as the presence of snow or unusual drought. AR-055 HOECKER, W.H., and L. MACHTA. Meteorological modeling of fallout. Health Physics 59(5):603-617 (1990). A meteorological transport and deposition interpolation model has been employed to estimate radioiodine deposition remote from the Nevada Test Site between points of observed deposition. The movement of the radioactive cloud across the United States is obtained from wind trajectories at various quasi-constant levels up to the top of the initial radioactive cloud. This model deals primarily with depositions beneath the passing cloud that are associated with precipitation. The fraction of radioiodine scavenged was inferred from a relationship derived statistically from fallout at locations having wet deposition. Therefore, estimation of deposition at locations between fallout observations is possible wherever precipitation occurred under the cloud. These estimates use very detailed historical records of precipitation available for virtually every county in the United States. Because significant dry and wet depositions also occur in areas that are not beneath the cloud, interpolation methods, such as kriging, are used to estimate fallout between the radioactivity observation locations. Ground level radioactivity measurements are required for these alternative methods. Such observations are validated before being used, often by the use of supplementary low-level trajectories. AR-056 HUBER, A.H. Wind tunnel and Gaussian plume modeling of building wake dispersion. Atmospheric Environment 25A:1237-1249(1991). This paper summarizes a study of the relationship between Gaussian plume models and wind tunnel models. Wind tunnel measurements of the distribution of tracer concentrations downwind of a point source in the near wake of a rectangular model building were evaluated. Profiles of mean velocity and turbulence were measured to characterize the flow. These experiments were conducted in both a low-turbulence boundary layer and a simulated atmospheric boundary layer. The study covered a range of four flow speeds and four different sized buildings. The differences in observed velocity and concentrations between the results for the low- turbulence and simulated atmospheric boundary layer flow were not significant very near the building, but these differences increased in significance at downstream distances greater than 10 times the building height. The transition from building- affected dispersion levels to levels that were not significantly different from dispersion without a building was a function of the size of the building. The application of a modified Gaussian plume model showed it to be a simple, well suited complement to wind tunnel measurements of mean concentrations. AR-057 HUBER, A.H., S.P. Arya, S.A. Rajala, and J.W. Borek. Preliminary studies of video images of smoke dispersion in the near wake of a model building. Atmospheric Environment 25A:1199-1209 (1991). 25 A summary of analysis of video images of smoke in a wind tunnel study of dispersion in the near wake of a model building is presented. The analyses provide information on both the instantaneous and time-average patterns of dispersion. Since the images represent vertically-integrated or crosswind-integrated smoke concentration only the primary spatial and temporal scales of pollutant dispersion can be examined. Special graphic displays of the results are presented to assist in the data interpretation. The video image format is shown to have great potential as an easily quantifiable electronic medium for studying the dispersion of smoke. AR-058 IRWIN, J.S., and J.O. Paumier. Characterizing the dispersive state of convective boundary layers for applied dispersion modeling. Boundary Layer Meteorology 53:267-296 (1990). Estimates from semiempirical models that characterize surface heat flux, mixing depth, and profiles of temperature, wind, and turbulence are compared with observation from atmospheric field studies conducted in Colorado, Illinois, Indiana, and Minnesota. Sodar observations are compared with tower measurements at the Colorado site, for wind and turbulence profiles. The median surface heat flux as calculated using surface-layer flux-profile relationships and an energy budget, was consistently overestimated by 20 to 80%. Several mixing-depth models were evaluated; (1) integration of the hourly surface heat flux and friction velocity, (2) solving for the time rate of change of profiles of virtual potential temperature, and (3) and interpolation scheme used by the U.S. Environmental Protection Agency in regulatory dispersion models. For the late afternoon, 80 to 90% of the estimates from the first and third models were within 40% of the observed values. For the morning hours after sunrise, all were less accurate. Temperature estimates from surface-layer flux-profile relationships, compared well with observations within the mixed layer, but were too low for the inversion layer aloft. Wind profiles were derived using surface-layer flux-profiles relationships, a windprofile power-law based on Pasquill stability category, and sodar measurements. The sodar measurements were superior to both types of model estimates. Turbulence profiles were derived from sodar measurements and from semiempirical similarity relationships based on mixing depth and Obukhov length. The scatter in the comparisons with the sodar observation is twice that seen in the comparisons with empirical profile relationship. Overall, it appears that uncertainty of as low as 20 to 30% in the characterization of the diffusion meteorology is the exception rather than the rule. AR-059 Jickells, T., R.R. Yaaqub, M.-M.Kane, A. Rendell, T. Davies, R. Harrison, C. Otley, R. Chester, G. Bradshaaw, J. MILLER, and M. Schulz. Atmospheric inputs to the North Sea: A progress report. Proceedings, EUROTRAC Symposium '90, P. Borrell et al., (eds.), 1991 SPB Academic Publishing, The Hague, The Netherlands, 85-86 (1991). No abstract. AR-060 Keene, W.C., A. A. P. PSZENNY, D.J. Jacob, R.A. Duce, J.N. Galloway, J.J. Schultz-Tokos, H. Sievering, and J.F. BOATMAN. The geochemical cycling of reactive chlorine through the marine troposphere. Global Biogeochemical Cycles 4(4):407-430 (1990). Heterogeneous reactions involving sea-salt aerosol in the marine troposphere are the major global source for volatile inorganic chlorine. We measured reactant and product species hypothesized to be associated with these chemical transformations as a function of phase, particle size, and altitude over the North Atlantic Ocean during the summer of 1988. Concentrations of HC1 were typically less than 1 .0 ppbv near the sea surface and decreased with altitude and with distance from the U.S. east coast. Concentrations of CI volatilized from aerosols were generally equivalent to the corresponding concentrations of HC1 and ranged from less than detection limits to 125 nmol m3 STP. Highest absolute and percentage losses of particulate CI were typically associated with elevated concentrations of anthropogenic combustion products. Concentrations of product nss S042' and N03' in coarse aerosol fractions indicate that on average only 38% of measured CI deficits could be accounted for by the combined effects of acid-base desorption and reactions involving nonacidic N gases. We hypothesize a mechanism for the CI loss initiated by reaction of 03 at sea-salt aerosol surfaces, generating C^, followed by rapid photochemical conversion of C^ to Hcl via CI atoms (CI ) and eventual recapture of Hcl by the aerosol. Simulations with a zero-dimension (O-D) photochemical model suggest that oxidation by CI may be an important tropospheric sink for dimethyl sulfide and hydrocarbons. Under low-NO, conditions, the rapid cycling of reactive CI would provide a catalytic loss mechanism for 03, which would possibly explain the low 03 concentrations often observed above the world's oceans. AR-061 Kim, Y.J., and J.F. BOATMAN. Corrections for the effects of particle trajectory and beam intensity profile on the size spectra of atmospheric aerosols measured with a forward scattering spectrometer probe. Journal of Atmospheric and Oceanic Technology 7:673- 680 (1990). Distortion of the size spectra measured with a forward scattering spectrometer probe (FSSP) under different transit time modes - "inhibit", "normal", and "delayed" - was evaluated using the theoretical analyses by Baumgardner and Spowart and the results of the response time and beam intensity profile measurements of the NOAA FSSP. The Baumgardner and Spowart work is extended to correct the 26 FSSP atmospheric aerosol data collected under the "inhibit" or "delayed" mode. A correction algorithm is developed using the non-negative least squares (NNLS) method to reconstruct the original size distribution from a distorted one measured with an FSSP under the inhibit or delayed mode. A lognormal fit to the corrected size spectra was able to successfully recover from the original size distributions from the distorted artificial ones obtained from the theoretical simulation of the FSSP performance. When the actual test flight data for atmospheric aerosols measured with the NOAA FSSP under the inhibit and delayed modes were corrected using the NNLS correction scheme, the two corrected size spectra converged, implying the measurement of the same sample of particles. AR-062 Kim, Y.J., and J.F. BOATMAN. Size calibration corrections for the forward scattering spectrometer probe (FSSP) for measurement of atmospheric aerosols of different refractive indices. Journal of Atmospheric and Oceanic Technology 7:681-688 (1990). The response of the Forward Scattering Spectrometer Probe (FSSP) is affected by the optical properties of measured particles. The manufacturer's size calibration data are specifically applicable to nonabsorbing water droplets. Response functions of the FSSP probe are calculated for different complex refractive indices corresponding to different types of atmospheric aerosols under various relative humidity conditions. Based on the results of these response calculations, new corrected size calibrations are determined for six relative humidity values (0%, 50%, 70%, 80%, 90% and 99%) and for three atmospheric aerosol types (Rural, Urban and Maritime). Sample calculations with these corrected size calibration data show that a significant underestimation of the aerosol size/volume distribution can result, especially for dry atmospheric aerosols, if the manufacturer's size calibration data are used. AR-063 Kim, Y.J., and J.F. BOATMAN. The effects that the optical properties of particles have on atmospheric aerosol measurements with optical particle spectrometers. Journal of Aerosol Science 21(l):s551-s554 (1990). The response of optical spectrometers is affected by the optical properties of measured particles. Kim and Boatman (1990a, 1990b) derived new corrected size calibration data, based on the Mie scattering response calculations for different refractive index values. The validity of these calibration corrections was assessed by comparing the aerosol scattering extinctions calculated from the spectrometer data with those measured simultaneously by a three-wavelength nephelometer. The agreement between the measured and calculated scattering extinctions was within 15%, when the size calibration data from the "rural" aerosol model were used. AR-064 Kim, Y.J., and J.F. BOATMAN. Vertical distribution of number concentration and size distribution of atmospheric aerosols over the central United States. Proceedings, SPIE - The International Society for Optical Engineering, Orlando, FL, April 18-20, 1990. Vol. 1312, 194-203(1990). Aircraft measurements of trace gases and atmospheric aerosols were performed over the central United States during four research field periods in 1988 as a part of the Central U.S. RADM Test and Assessment Intensives (CURTAIN). Aerosol size distributions were measured at six altitudes between 700 and 3200 m above sea level over the size range 0.1—32 f*m, using two Particle Measuring Systems (PMS) probes; an active scattering aerosol spectrometer probe (ASASP) and a forward scattering spectrometer probe (FSSP), mounted on the wings of the NOAA King Air research aircraft. The FSSP data were first corrected using a scheme which accounts for the effects of the probe's electronic response time and nonuniformity in the laser beam intensity profile on the measured aerosol size spectra. Vertical profiles of the average aerosol concentration show seasonal characteristics, with maximum concentrations during summer and minimum concentrations during winter. In summer, the aerosol number concentration in the fine-particle mode is rather constant about 2,000 cm"3 up to about 1900 m asl level. Number concentration of the soil-derived aerosols in the coarse-particle mode is maximized during spring. The measured aerosol number size distributions exhibit typically bi-modal distributions for both boundary layer and free tropospheric aerosols. Each measured number size distribution is approximated with a sum of two lognormal distributions using a lognormal fitting routine. The aerosol size distribution data measured in the boundary layer and in the free troposphere are compared with the LOWTRAN "Rural" aerosol model and Tropospheric aerosol model, respectively. AR-065 Kim, Y.J., H. Sievering, and J.F. BOATMAN. Volume and surface area size distribution, water mass and model fitting of GCE/CASE/WATOX marine aerosols. Global Biogeochemical Cycles 4(2): 165-177 (1990). As a part of the Global Change Expedition/Coordinated Air-Sea Experiment/Western Atlantic Ocean Experiment (GCE/CASE/ WATOX), size distributions of marine aerosols were measured at two altitudes of about 2750 and 150 m above sea level (asl) over the size range 0.1-32 /tm. Lognormal fitting was applied to the corrected aerosol size spectra to determine the volume and surface area size distributions of the CASE- WATOX marine aerosols. Each aerosol size distribution was fitted with three lognormal distributions representing fine-, large-, and giant-particle modes. Water volume fraction and dry particle size of each aerosol size distribution were also calculated using empirical formulas for particle size as a function of relative humidity and particle type. Because of the increased influence 27 from anthropogenic sources in the continental United States, higher aerosol volume concentrations were observed in the fine-particle mode nearshore off the east coast; 2.11 and 3.63 ^m3 cm1 for free troposphere (FT) and marine boundary layer (MBL), compared with the open- sea Bermuda area values; 0.13 and 0.74 urn' cm'3 for FT and MBL. The large-particle mode exhibits the least variations in volume distributions between the east coast and open-sea Bermuda area, having a volume geometric median diameter (VGMD) between 1.4 and 1.6 |im and a geometric standard deviation between 1.57 and 1.68. For the giant-particle mode, larger VGMD and volume concentrations were observed for marine aerosols nearshore off the east coast than in the open-sea Bermuda area because of higher relative humidity and higher surface wind speed conditions. Wet VGMD and aerosol water volume concentrations at 15 m asl ship level were determined by extrapolating from those obtained by analysis of the CASE-WATOX aircraft aerosol data. Abundance of aerosol water in the MBL serves as an important pathway for heterogeneous conversion of SOj in sea salt aerosol particles. AR-066 Kopcewicz, B., C. NAGAMOTO, F. PARUNGO, J. HARRIS, J. MILLER, H. Sievering, and J. Rosinski. Morphological studies of sulfate and nitrate particles on the east coast of North America and over the North Atlantic Ocean. Atmospheric Research 26:245-271 (1991). Shipborne and airborne aerosol samples were collected during the Coordinated-Air-Sea Experiment (CASE) over the western North Atlantic Ocean. The experiment was accompanied by measurements on shore near Hampton, Virginia. Individual particle morphology, size, and concentration were analyzed with an electron microscope. Particles containing sulfuric acid, sulfate, nitric acid, and nitrate were identified with various morphological tests. Temporal and spatial variations of aerosol physicochemical characteristics were studied in relation to atmospheric parameters. A diurnal solar radiation effect on concentration and chemical composition of small sulfate-containing particles (0.2 ^m < d < 0.7 jim) was observed, indicating that the particles are the product of photochemical reaction. Sulfuric acid particles were most frequently observed near noon, and ammonium sulfate particles were dominant at night. The concentration of sulfate particles also depends on air trajectories, including sources of air mass, wind direction, and wind speed. Meteorological conditions (humidity and solar radiation) influenced the concentrations of nitrate-containing aerosols including nitric acid particles. High concentrations of nitrate particles were found only near the source; sulfate particles could transport to greater distances. For both sulfate particles and nitrate particles, concentrations were higher at low altitudes (< 150 m) than at high altitudes (2600 m). AR-067 Lee, J.T., D.L. Call, R.E. LAWSON, Jr., W.E. Clements, and D.E. Hoard. A video image analysis system for concentration measurements and flow visualization in building wakes. Atmospheric Environment 25 A: 121 1-25 (1991). A video image analysis technique for concentration measurements and flow visualization was developed for the study of diffusion in building wakes and other wind tunnel flows. Smoke injected into the flow was photographed from above with a video camera, and the video signal was digitized in real time during the experiment and during playback with a video image analysis system. The relation between the digitized smoke intensity and the vertically- integrated concentration of smoke particles was obtained from calibration experiments in which the smoke was replaced by a mixture of ethane and air. The time-averaged vertically-integrated concentration of the ethane tracer was measured at discrete points throughout the flow field and correlated with the time-averaged smoke intensity data. After the system was calibrated, the instantaneous and time-averaged fields of vertically integrated concentration were obtained by simply photographing the smoke plume. Color-contoured images of the plume were created and displayed in real time thus creating a pseudo-color movie that was very useful for flow visualization. This technique was used to study the effects of building geometry and source location on the concentration and flow patterns in building wakes. AR-068 Luria, M., and H. Sievering. Heterogeneous and homogeneous oxidation of S02 in the remote marine atmosphere. Atmospheric Environment 25A(8):1489-1496 (1991). A photochemical computer model was used to simulate production and removal of S-containing species in the remote marine atmosphere. The results of aircraft and shipboard trace gas and aerosol measurements, performed during the 1988 Coordinated Air-Sea Experiment/Western Atlantic Ocean Experiment (CASE/WATOX) were used for the model input. The modeling revealed that homogeneous oxidation can not explain the existence of excess sulfate on large particles. Thus, it must be supplemented by an additional process in order to obtain a balance between sources and sinks of sulfur species. A proposed heterogeneous pathway consisting of SOj condensation on and oxidation in aerosol particles was tested. With the addition of the heterogeneous process, and assuming that the rate-determining step is condensation of SO^ on large particles by molecular diffusion, it was possible to simulate the experimentally observed concentrations of all sulfur species. Results show that the upper limit for rate constants (dictated by diffusion theory) was 50-1500 times larger than the rate constants used in the model for the condensation process. The balance between sources and sinks, using this model, requires the nearly 60% of the observed oxidation should occur via the heterogeneous channel at a rate of about 0.015h'. The 24h average homogeneous rate was approximately O.Olh'1. 2H AR-069 Luria, M., C.C. VAN VALIN, R.L. GUNTER, D.L. WELLMAN, W.C. Keene, J.N. Galloway, H. Sievering, and J.F. BOATMAN. Sulfur dioxide over the western north Atlantic ocean during GCE/CASE/WATOX. Global Biogeochemical Cycles 4(4):381-393 (1990). Sulfur dioxide (SOj) was measured with a pulsed fluorescence analyzer and filter pack system from the instrumented NOAA King Air aircraft. The measurements were part of the GCE/CASE/WATOX project in July 1988 and included a series of eight flights of 4-hour duration each. During the first four flights the atmosphere was sampled over the Atlantic Ocean within 250 km east of Newport News, Virginia; during the remaining four flights the atmosphere in the vicinity of Bermuda was sampled. S02 data were collected at two elevations: about 750 mbar in the free troposphere (FT), and in the lower part of the boundary layer (BL) at about 1000 mbar. Average BL concentrations were almost 10 times greater near the east coast than near Bermuda (500 ±800 pptv versus 60 + 40 pptv). FT concentrations near the east coast also were greater than near Bermuda but by a lesser factor (1 10±50 pptv versus 70±40 pptv). The data from the continuous analyzer compared favorably with the data obtained from filter samples collected concurrently. SO^ data from this study are somewhat lower (factor of 0.6-0.9) than previous measurements at both sites. Average concentrations of SO, measured near Bermuda (60 pptv) were in the range of those observed in the remote marine atmosphere, although higher SO, concentrations (up to 450 pptv) were also detected on occasion. The SOj removal rate over the western Atlantic Ocean, near the east coast, is estimated empirically at 0.07±0.03 hour'1. Analyses of the known removal mechanisms suggested that the main removal mechanism is dry deposition. AR-070 MAUL, G.A., and K. Hanson. Interannual coherence between North Atlantic atmospheric surface pressure and composite southern U.S.A. sea level. Geophysical Research Letters 18(4):653-656 (1991). Annual mean sea levels along the southern United States have been examined for interannual variability. Fifteen sea level stations from Cape Hatteras to the Rio Grande that best covered the three lunar nodal cycles from 1931-1987 were selected for analysis. Linear trends, ranging from +0.2 cm/yr to +1.4 cm/yr were subtracted from their respective series, leaving remarkably similar residuals. The composite time series of the 15 residuals was compared with time series of surface air pressure over the North Atlantic Ocean during the period 1947- 1987. The best correlation is a negative relationship between composite sea level and wintertime air pressure north of 45°N, and a positive relationship from 20°-45°N. The most significant correlations (-0.73 and +0.51) were found for 60°N, 20°W and for 30°N, 25 °W respectively. Wintertime meridional air pressure gradient between these two latitudes represents about 50% of the variance in composite annual mean sea level. Both the sea level and air pressure time series had significant spectral peaks at 13.3 and 4.4. years, with about 52% of the covariance coming from these two periods. AR-071 McHenry, J.N., and R.L. DENNIS. Partitioning of the sulfate budget into gas- and aqueous-phase components in the Regional Acid Deposition Model (RADM). Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 143-147 (1991). Extended abstract. AR-072 McMILLEN, R.T. An estimate of the spatial variability of trace gas deposition velocities. Contract Project 9956, U.S. Environmental Protection Agency, Washington, DC, 59 pp. (1990). Dry deposition of gaseous and particulate materials constitutes a significant fraction of the total acidic deposition to the surface. Measurements of this quantity are difficult to obtain and are usually available only for a single location. An understanding of the spatial variability of dry deposition is fundamental to extending site-specific measurements to subregional and regional scales. This study estimates the spatial variability of the dry deposition velocity over three 84 km by 84 km study areas by use of a deposition velocity model. Inputs to the model consist of meteorology, vegetation type, and terrain type. Meteorological data were available from an ongoing dry deposition research program; terrain and vegetation data were derived from U.S. Geological Survey (USGS) Digital Elevation Models and Landsat Thematic Mapper data, respectively. Model run results are presented for one month's data at one site and for 12 weekly averages at all three sites. Verification of the technique is presented, but only at a single point. AR-073 McMILLEN, R.T., and T.L. CRAWFORD. Direct measurement of CO^ exchange to the ocean using a ship-mounted eddy correlation system. Preprints, Seventh Symposium on Meteorological Observations and Instrumentation and Special Sessions on Laser Atmospheric Studies, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 46-50 (1991). Extended abstract. 29 AR-074 Meyer, E.L., N.C. POSSIEL, D.C. DOLL, K.A. Baugues, and K.A. Baldridge. A summary of ROMNET results and outputs. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991 . American Meteorological Society, Boston, 246-249 (1991). Extended abstract. AR-075 MEYERS, T.P., and C.B. BAKER. Ocean/atmosphere exchange of momentum, heat, moisture and CQ in shallow water zones. Preprints, Seventh Symposium on Meteorological Observations and Instrumentation and Special Sessions on Laser Atmospheric Studies, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 26-29 (1991). Extended abstract. AR-076 MEYERS, T.P., and D.D. BALDOCCHI. The budgets of turbulent kinetic energy and Reynolds stress within and above a deciduous forest. Agricultural and Forest Meteorology 53:207-222 (1991). Mean turbulence statistics obtained within and above a deciduous forest are used to examine the components in the budget equations for turbulent kinetic energy (TKE) and tangential shear stress. Comparisons from the measurements are made with predictions from a higher- order closure model for canopy flow. Wake-generated turbulence was found to exceed shear-produced turbulence in all but the upper level of the canopy. Beneath the tree crowns, turbulent transport was the dominant source of TKE and tangential shear stress. Below — 75% of the canopy height, the magnitude of all the TKE and shear stress budget components is small compared with values above this height, and the vertical gradients of second- and third-order moments are small. The turbulence statistics observed within the deciduous forest are remarkably similar to that observed within a tropical forest, which has a similar distribution of leaf area. When compared with results from experiments conducted in other canopies, the importance of the quantity and vertical distribution of the plant area in determining the turbulence structure is reinforced. AR-077 MEYERS, T.P., B.B. HICKS, R.P. HOSKER, JR., J.D. Womack, and L.C. Satterfield. Dry deposition inferential measurement techniques — II. Seasonal and annual deposition rates of sulfur and nitrate. Atmospheric Environment 25A(10):2361-2370(1991). Since the autumn of 1984, a dry deposition research network has been operated to develop and refine methods to make defensible estimates of dry deposition rates of SCt,, sulfate and nitrate (particulate and gaseous) on routine basis. Ten of the sites are located in the eastern part of the U.S. while two are located in the western half. Annual dry deposition rates of sulfur (SO; + S042 ) are estimated to range from 2.5 kg ha"1 at Whiteface Mountain, NY to 14 kg ha"1 at Argonne, IL. The majority of deposited sulfur was delivered in the form of SO^. Deposition rates were highest during the summer season even though SOj concentrations peaked during the winter months because the estimated deposition velocities (VJ were much greater in the summer. Nearly all of the dry deposited nitrogen (HN03 + N03 ) was in the form of HNO3. An annual cycle was not evident in the time series of nitrogen deposition rates. For both sulfur and nitrogen, dry deposition was estimated to provide between 30% and 50% of the total input from the atmosphere (wet + dry) for all sites in the eastern U.S. AR-078 Mikkelsen, T., A. Hansen, R.M. ECKMAN, and S. Thykier-Nielsen. Project WIND, phase IV, dispersion study: Aerial smoke plume observations and surface layer turbulence measurements, Part II, Wind and temperature spectral analysis. Ris0-M-2718(pt.2). Rise National Laboratory, Roskilde, Denmark, 102 pp. (1990). This data report contains results from selected time series and spectral analyses of the turbulent wind and temperature measurements performed by Rise National Laboratory during the AMADEUS "Smoke and Diffusion Tests" of Project WIND, Phase rV, which took place as a cooperative research oriented study between the U.S. Army Atmospheric Sciences Laboratory (ASL) and U.S. Department of Agricultural Forest Service (USDAFS) in the Meadow Brook Valley near Read Bluff, California, during the period between 3 September and 7 October 1987. In Part I of this study (January 1989), Riso National Laboratory reported sonic-anemometer measurements of 10-min averaged surface-layer scaling parameters such as surface heat flux, shear stress, turbulence levels and atmospheric stability measured at two locations in the Meadow Brook Valley floor accompanied by aerial photography of the valley-floor smoke puff and plume spread. The present study provides time series plots of the turbulent (10 Hz block-averaged) wind and temperature signals as recorded by sonic- anemometers/thermometers at the 7-m level above the Meadow Brook Valley floor during the AMADEUS trials. The time series are further processed into energy spectra for the three wind components (u', v', w') and fluctuating temperature (T') and here presented together with their relevant scaling parameters calculated by the correlation method. The time series and spectra provide flow and diffusion 30 modellers of the AMADEUS experiments with an insight in the turbulent scales and energies most responsible for the observed flow and diffusion processes. Furthermore they provide high-resolution boundary-layer flow and turbulence measurements for model simulation of the individual experiment. All data have been transferred to ASL on IBM PC -compatible diskettes. AR-079 Musick, H.B., and D.A. GILLETTE. Field evaluation of relationships between a vegetation structural parameter and sheltering against wind erosion. Land Degradation and Rehabilitation 2:87-94 (1990). Measurements of natural vegetation canopies and of threshold friction velocities for soil movement were made at three arid and semiarid field sites. Threshold friction velocities for the vegetated surface and for bare soil were used to evaluate the partitioning of shear stress between that absorbed by the plant canopies and that absorbed by the soil surface (this potentially causing movement of soil particles). Canopy measurements were used to estimate lateral cover (total frontal-silhouette area per unit ground area), a parameter shown by previous laboratory studies to be a good predictor of shear stress partitioning. The relationship between lateral cover and shear stress partitioning for the field sites agreed with the laboratory results of Gillette and Stockton (1989). Results indicate that the protective influence of vegetative cover against wind erosion can be successfully predicted using simple measurements of vegetation canopy structure. AR-080 NAGAMOTO, C, F.P. PARUNGO, B. Kopcewicz, and M.Y. Zhou. Chemical analysis of rain samples collected over the Pacific Ocean. Journal of Geophysical Research 95:22,243-22,354(1990). During seven research cruises in the Pacific Ocean from 1984 to 1989 we collected rain samples for chemical analyses. The geographical and temporal variations of rain chemistry were studied in relation to natural and anthropogenic sources and transport of the constituents. The pH values of rain samples ranged from 3.9 to 7.2, with a mean of 5.6 (n = 104, a = 0.5). The most acidic rain was found near the big ports, where S04" and N03" concentrations in rain were also the highest. The data indicated that wet deposition transports anthropogenic pollution from continents to oceans. Enrichments of Ca++ and K+, which are compared to Na+ in sea-water, were observed in all rain samples throughout the ocean. However, their enrichment factors (EF) decrease with distance from land, signifying the extent of transport of crustal elements through cloud process and wet deposition. The EFs of Mg+ + were close to unity, indicating its common origin with Na*. The EFs of CI" in most rain samples were less than 1, indicating loss of CI in aerosols, cloud droplets, or rain drops. High Efs of SQ," were also observed at the equatorial regions, where biogenic production of dimethyl sulfide is well known. During the 1987 El Nino anomaly the sulfate aerosol distribution and rainfall patterns altered with air trajectories. The effects of sulfate aerosol on cloud condensation and rainfall amount in various regions during normal years and the El Nino anomaly are discussed. AR-081 NAPPO, CJ. Sporadic breakdowns of stability in the PBL over simple and complex terrain. Boundary-Layer Meteorology 54:69-87 (1991). Breakdowns of stability in the PBL are examined using one-minute average horizontal wind speeds and temperatures observed over many nights at stations located in simple and complex terrain. The analysis is based on the temporal behavior of the wind speed- temperature covariance, which is obtained by digital bandpass filtering. It is shown that breakdowns are a common feature of the stable PBL over both simple and complex environments. Vertical fluxes of heat during breakdowns are estimated to be a significant fraction of the nighttime average heat flux. It is hypothesized that a major portion of the nighttime vertical transfer of heat, momentum, and atmospheric pollutants occurs during periods of stability breakdowns. AR-082 NAPPO, C.J. Sporadic turbulence and dispersion in the stable boundary layer. In: Air Pollution Modeling and Its Application Vm. H. van Dop and D.G. Steyn (Eds.), Plenum Press, NY, 705-712 (1991). No abstract. AR-083 NAPPO, C.J., T.L. CRAWFORD, R.M. ECKMAN, and D.L. AUBLE. A sensitive electronic microbarograph network. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991 . American Meteorological Society, Boston, J179-J181 (1991). Extended abstract. 31 AR-084 PARUNGO, F., C. NAGAMOTO, B. Kopcewicz, J. HARRIS, Z. Mingyu, L. Naiping, and S. Hoyt. Geographic and temporal variations of sulfate aerosols over the Pacific Ocean. Acta Oceanologica Sinica 10(l):17-72 (1991). To investigate the life cycle of marine sulfate aerosols, chemicophysical characteristics of marine aerosols were measured during five cruises in the Pacific Ocean. Dimethyl sulfide concentrations in seawater and in the air were also measured. The geographic variation of sulfate-aerosol concentrations was studied in relation to biogenic and anthropogenic sources, transport with air trajectories, and chemical transformations in the atmosphere . The highest concentrations were found near Asian and American ports, indicating anthropogenic pollution is the major sulfate aerosols source. Higher concentrations were observed in the upwelling regions than in the oligotrophic areas. Along the coastal regions, both mass and number concentrations of sulfate aerosols depended on wind direction and wind speed, and land- breeze and sea-breeze oscillations; no clear diurnal variation was detected. In pelagic areas, along the equator, the concentrations of small sulfate particles showed a maximum in the afternoon and the minimum at night, indicating photo-oxidation as an important process for gas- to-particle conversion. Higher sulfate-aerosol concentrations were observed in spring than in autumn and higher concentrations were found during the La Nina anomaly than during the El Nino anomaly. Biogenic source of sulfate aerosols has an important role in the remote ocean. Case studies of sulfate-aerosol distributions are discussed. AR-085 Paumier, J.O., and J.S. IRWIN. Comparison of modified Carson and EPA mixing height estimates using data from five field experiments. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 282-285 (1991). Extended abstract. AR-086 PERRY, S.G., D.J. Burns, and A.J. Cimorelli. User's guide to CTDMPLUS: Volume 2. The screening mode (CTSCREEN). EPA/600/8-90/087, Atmospheric Research and Exposure Assessment Laboratory, Research Triangle Park, NC (1991). The EPA's Technology-Transfer Workgroup has developed a screening version (denoted as CTSCREEN) of the Complex Terrain Dispersion Model, CTDMPLUS. CTSCREEN uses an array of predetermined meteorological conditions to model the user supplied source- terrain configuration. CTSCREEN yields estimates of maximum 1-h, 3-h, 24-h, and annual impacts that are conservative with respect to CTDMPLUS estimates using a full year of on-site data. In comparison with other complex terrain screening models, CTSCREEN provides estimates that most consistently reflect those of CTDMPLUS. AR-087 PERRY, S.G., J.O. Paumier, and D.J. Bums. Evaluation of the EPA complex terrain dispersion model (CTDMPLUS) with the Lovett Power Plant data base. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 189-192 (1991). Extended abstract. AR-088 PIOTROWICZ, S.R., C.J. FISCHER, and R.S. ARTZ. Ozone and carbon monoxide over the North Atlantic during a boreal summer. Global Biogeochemical Cycles 4(2):215-224 (1990). Ozone mixing ratios observed on a cruise from the east coast of North America to Bermuda, to Iceland, to the Azores and terminating in Barbados in a boreal summer exhibit wide variability. Increases above a North Atlantic background of 10-20 ppbv appear to be associated with transport from terrestrial systems. In the central gyre of the North Atlantic and the tropical North Atlantic, ozone mixing ratios below 10 ppbv are commonly observed when the air being sampled does not have a recent (10 days) history of terrestrial input. Carbon monoxide mixing ratios within the boundary layer vary latitudinally from an average of 124 ppbv in the westerlies to 88 ppbv in the tropical North Atlantic. Variability in the distribution of CO appears to be dominated by transport from terrestrial source regions. AR-089 PJTCHFORD, M.L., B.V. Polkowsky, M.R. McGown, W.C. Malm, J.V. Molenar, and L. Mauch. Percent change in extinction coefficient: A proposed approach for federal visibility protection strategy. In Visibility and Fine Particles, C. V. Mathai (ed.), AWMA Transactions, Series No. 17, U.S. EPA, AREAL, Research Triangle Park, NC. A&WMA, Pittsburgh, 37-49 (1990). 32 This paper describes a regulatory strategy for protecting visibility from hazes (as opposed to elevated layers and plumes). The proposed strategy combines two features which have been mutually exclusive in previously considered strategies. It is simple (simple to state, to understand, and to apply) and it will provide an appropriate level of visibility protection regardless of the nature of the scene or present air quality conditions. The strategy would establish easily predictable control levels now and in the future. The strategy has two parts. The first part provides an approach for preventing additional noticeable visibility impairments while the second part provides a mechanism for gradually improving visual air quality to any predetermined levels (e.g., in Federal Class I areas the goal is Congressionally established at natural background levels). Perceptual arguments that support the nature and levels of the proposed strategy are presented, including discussion of a series of scenic photographs with computer generated hazes that were shown during the presentation. Also presented is a discussion of the efforts that would be required to establish and implement such a strategy. AR-090 PLEIM, J.E., J.S. Chang, and K. Zhang. A nested grid mesoscale atmospheric chemistry model. Journal of Geophysical Research 96(D2):3065-3084(1991). A nested grid version of the Regional Acid Deposition Model (RADM) has been developed. The horizontal grid interval size of the nested model is 3 times smaller than that of RADM (80/3 km = 26.7 km). Therefore the nested model is better able to simulate mesoscale atmospheric processes while maintaining consistency with larger-scale features. The nested model uses dynamic boundary conditions along inflow boundaries which are interpolated from coarse grid model (RADM) results. Since the nesting is one-way, the outflow boundary conditions are specified to minimize numerical reflections. Three-day wet deposition amounts of sulfate and nitrate simulated by the nested grid version of RADM as well as the coarse grid version were compared to measurements made by the regional scale network during the Oxidizing and Scavenging Characteristics of April Rains (OSCAR) IV experiment. Both models were able to predict wet depositions of sulfate to within a factor of 2 for over 80% of the sampling sites. Nitrate predictions were slightly worse with just over 70% of the pairs within a factor of two for both models. Although the nested grid model showed no improvement over the coarse grid model in terms of point by point comparisons, it did demonstrate the ability to predict a more realistic range and spatial variability of wet deposition amounts. Plots of predicted deposition fields show that the nested model predicted values similar to the observations in their vicinity more often than did the coarse grid model. Nested model simulations of wet deposition were also compared to measurements made by a high density sampling network over a 1 10 x 110 km area of northeastern Indiana. Most of the spatial features of the observed distribution were well simulated by the model demonstrating the nested model's ability to resolve processes on scales which are subgrid to the coarse grid model. The predictions of wet depositions by both models were in better agreement with observations than were predictions of precipitation. Since the OSCAR IV experiment was characterized by very efficient washout, the rate of wet deposition was often primarily controlled by the rate of supply of airborne material to the precipitating system rather than aqueous oxidation and precipitation processes. Therefore, errors in precipitation rate had little impact on wet deposition predictions. AR-091 Polkowsky, B.V., and M. PITCHFORD. Discussion of federal regulatory approaches for addressing regional visibility impairment. In Visibility and Fine Particles, C. V. Mathai (ed.), AWMA Transactions, Series No. 17, U.S. EPA, AREAL, Research Triangle Park, NC. A&WMA, Pittsburgh, 27-36 (1990). Over the past decade the U.S. Environmental Protection Agency (EPA), together with the Federal Land Managers and States have implemented a program for visibility protection in federal Class I areas. This program was set forth in regulations promulgated by EPA in 1980. The program is focused on "reasonably attributable" impairment cases and review of major new source impairments to Class I areas. At this time, it would be useful to review options available to EPA to address non-source specific visibility impairments in a regulatory manner. Regional haze regulatory approaches under the current Clean Air Act, and proposed revisions to that Act, range from a simple fine particle concentration regulation to a regulation based on changes in extinction levels in Class I areas. The ability of these regulatory frameworks to directly address visibility impairment and to work in conjunction with other regional effects programs varies greatly. AR-092 POOLE-KOBER, E.M., and H.J. VIEBROCK. Fiscal year 1989 summary report of NOAA Atmospheric Sciences Modeling Division support to the U.S. Environmental Protection Agency. NOAA TM ERL ARL-187 (PB91 141317), 60 pp. (1990). During FY-1989, the Atmospheric Sciences Modeling Division provided meteorological research and operational support to the U.S. Environmental Protection Agency. Basic meteorological operational support consisted of applying dispersion models and conducting dispersion studies and model evaluations. The primary research effort was the development and evaluation of air quality simulation models using numerical and physical techniques supported by field studies. Modeling emphasis was on the dispersion of photochemical oxidants and particulate matter on urban and regional scales, dispersion in complex terrain, and the transport, transformation, and deposition of acidic materials. Highlights included development of the Regional Acid Deposition Model Version 2.0 and a sulfate tracking version of the RADM Engineering Model; development of a method of aggregating data from 3-day episodes to form seasonal and annual averages of RADM predictions; development of a Biogenic Emissions Inventory System (BEIS); continuation of the Acid-MODES field study; evaluation of the second-generation Regional Oxidant Model; completion of the Complex Terrain Dispersion Model with algorithms for 33 unstable situations; conduct of dense-gas dispersion studies in a neutrally stratified wind tunnel; conduct of the Boston Wastewater Outfall study in a stratified towing tank; and conduct of a wind-tunnel study of smoke dispersion in building wakes. AR-093 POOLE-KOBER, E.M., and H.J. VIEBROCK. Fiscal year 1990 summary report of NOAA Atmospheric Sciences Modeling Division support to the U.S. Environmental Protection Agency. NOAA TM ERL ARL-188, 65 pp. (1991). During FY-1990, the Atmospheric Sciences Modeling Division provided meteorological research and operational support to the U.S. Environmental Protection Agency. Basic meteorological operational support consisted of applying dispersion models and conducting dispersion studies and model evaluations. The primary research effort was the development and evaluation of air quality simulation models using numerical and physical techniques supported by field studies. Modeling emphasis was on the dispersion of photochemical oxidants and particulate matter on urban and regional scales, dispersion in complex terrain, and the transport, transformation, and deposition of acidic materials. Highlights included expansion of the Regional Acid Deposition Model/Engineering Model family to include the Tagged Species Engineering Model, the Non-Depleting Model, and the Sulfate Tracking Model; completion of the Acid-MODES field study; completion of the RADM2.1 evaluation; completion of the atmospheric processes section of the National Acid Precipitation Assessment Program 1990 Integrated Assessment; conduct of the first field study to examine the transport and entrainment processes of convective clouds; development of a Regional Oxidant Model-Urban Airshed Model interface program; conduct of an international sodar intercomparison experiment; incorporation of building wake dispersion in numerical models; conduct of wind-tunnel simulations of stack-tip downwash; and initiation of the publication of SCRAM NEWS. AR-094 POSSIEL, N.C., L.B. Milich, and B.R. Goodrich (Eds.). Regional Ozone Modeling for Northeast Transport (ROMNET) and appendices. EPA-450/4-91-002a,b, Office of Air Quality Planning and Standards, Research Triangle Park, NC, 696 pp. (1991). No abstract. AR-095 PSZENNY, A.A.P., J.N. Galloway, R.S. ARTZ, and J.F. BOATMAN. Overview of the 1988 GCE/CASE/WATOX studies of biogeochemical cycles in the North Atlantic Ocean. Global Biogeochemical Cycles 4(2): 121-131 (1990). The 1988 Global Change Expedition/Coordinated Air-Sea Experiment/Western Atlantic Ocean Experiment (GCE/CASE/WATOX) was a multifaceted research program designed to study atmospheric and oceanic processes affecting the biogeochemical cycles of carbon, nitrogen, sulfur, and trace metals in the North Atlantic Ocean region. Field work included (1) a 49-day research cruise aboard NOAA ship Mt. Mitchell (Global Change Expedition) from Norfolk, Virginia, to Bermuda, Iceland, the Azores, and Barbados, (2) eight flights of the NOAA King Air research aircraft, four off the Virginia Capes and four near Bermuda (CASE/WATOX), and (3) a research cruise aboard the yacht Fleurtje near Bermuda (WATOX). Objectives of GCE/CASE/WATOX were (1) to examine processes controlling the mesoscale distributions of productivity, chlorophyll, and phytoplankton growth rates in Atlantic surface waters, (2) to identify factors controlling the distribution of ozone in the North Atlantic marine boundary layer, and (3) to estimate the contributions of sources on surrounding continents to the biogeochemical cycles of sulfur, nitrogen, and trace metals over the North Atlantic region during the boreal summer season. The individual papers in this and the next two issues of Global Biogeochemical Cycles provide details on the results and analyses of the individual measurement efforts. This paper provides a brief overview of GCE/CASE/WATOX. AR-096 RAO, K.S., and J.M. GODO WITCH. The inclusion of pollutant removal processes in urban air quality models. Proceedings, 1990 Environmental Protection Agency/Air & Waste Management Association International Symposium on Measurement of Toxic and Related Air Pollutants, Raleigh, NC, April 30-May 4, 1990. U.S. EPA, Washington, DC, 881-886 (1990). Gaseous and particulate pollutants emitted into the atmosphere are removed by several natural processes. Important among them are the dry deposition of pollutants at the earth's surface, and chemical transformation in the atmosphere. These removal mechanisms affect the pollutant concentrations and residence times in the atmosphere and, therefore, it is necessary to account for them in air quality models. This is particularly important for urban air quality models, which are often used to assess the risk associated with chronic exposure of population to toxic air contaminants. This paper describes a methodology for including dry deposition and a first-order chemical transformation in urban air pollution models based on the Gaussian-diffusion framework. The concentration algorithms for point sources are derived from analytical solutions of a gradient-transfer model. In the limit, when deposition and settling velocities and the chemical transformation rate are zero, these expressions for various stability and mixing conditions reduce to the familiar Gaussian plume diffusion algorithms without the removal processes. The point-source algorithms are integrated to obtain the concentrations due to emissions from distributed urban area sources. A new mathematical approach, based on mass budget considerations, is outlined to derive simple expressions for ground-level 34 concentrations. The concentration and deposition flux formulations described in this paper are currently used in several of EPA's air quality models. AR-097 Rao, S.T., J.-Y. Ku, and K.S. RAO. Analysis of toxic air contaminant data containing concentrations below the limit of detection. Journal of the Air and Waste Management Association 41(4):442-448 (1991). Air quality data often contain several observations reported only as below the analytical limit of detection (LOD), resulting in "censored" data sets. Such censored and/or truncated data sets tend to complicate statistical analysis. This paper discusses various procedures for estimating mean concentration and its 95 percent confidence bounds from air contaminant data sets which contain values that are reported as below the LOD. A quantitative approach for assessing the uncertainty inherent in the estimated mean concentration due to (a) presence of values below the LOD in the data set, and (b) natural variability of atmospheric concentration data, is described. The utility of this approach in the analysis and interpretation of ambient pollutant concentration data is demonstrated for both hypothetical and observed singly-censored data sets, and for a multiply-censored, multi-pollutant observed concentration data set. The methodologies discussed here should be particularly useful in verifying compliance with environmental regulations, and in estimating the risks associated with long-term exposure of populations to toxic air contaminants and assessing the uncertainty associated with these estimates. AR-098 Rao, S.T., J.-Y. Ku, and K.S. RAO. Analysis of air pollutant concentrations below the detection limit. Proceedings, 1990 Environmental Protection Agency/ Air & Waste Management Association International Symposium on Measurement of Toxic and Related Air Pollutants, Raleigh, NC, April 30-May 4, 1990, EPA/600/9-90/026. U.S. EPA, Washington, DC, 1044-1049 (1990). Extended abstract. AR-099 Rao, S.T., J.-Y. Ku, and K.S. RAO. Sampling strategies for toxic air contaminants. Risk Analysis 1 1(3):441-451 (1991). Annual concentrations of toxic air contaminants are of primary concern from the perspective of chronic human exposure assessment and risk analysis. Despite recent advances in air quality monitoring technology, resource and technical constraints often impose limitations on the availability of a sufficient number of ambient concentration measurements for performing environmental risk analysis. Therefore, sample size limitations, representativeness of data, and uncertainties in the estimated annual mean concentration must be examined before performing quantitative risk analysis. In this paper, we discuss several factors that need to be considered in designing field-sampling programs for toxic air contaminants and in verifying compliance with environmental regulations. Specifically, we examine the behavior of S02, TSP, and CO data as surrogates for toxic air contaminants and as examples of point source, area source, and line source-dominated pollutants, respectively, from the standpoint of sampling design. We demonstrate the use of boot-strap resampling method and normal theory in estimating the annual mean concentration and its 95% confidence bounds from limited sampling data, and illustrate the application of operating characteristic (OC) curves to determine optimum sample size and other sampling strategies. We also outline a statistical procedure, based on a one-sided f-test, that utilizes the sampled concentration data for evaluating whether a sampling site is in compliance with relevant ambient guideline concentrations for toxic air contaminants. AR-100 Ray, J.D., M. Luria, D.R. Hastie, S. Malle, W.C. Keene, and H. Sievering. Losses and transport of odd nitrogen species (NOy) over the western Atlantic ocean during GCE/CASE/WATOX. Global Biogeochemical Cycles 4(3):279-295 (1990). Aircraft and shipboard measurements of mixing ratios for odd nitrogen species (NOy) were made over the western Atlantic Ocean during the summer of 1988. NOy in boundary layer air ranged from 4.8 ppbv near the U.S. east coast to 1.7 ppbv near a research ship 160 km from the coast. A vertical NO, gradient was observed near shore; mixing ratios decreased with altitude from 3.0 ppbv at 150 m to 1.3 ppbv at 2600 m. A smaller NOy gradient was observed near the ship with mixing ratios also decreasing with altitude. During the observation period of this experiment, a high-pressure system over the mid-Atlantic limited advection of polluted continental air to a band just along the coast, thus preserving less polluted conditions to the east of the band. Loss rates for NOy advected from the continent, based on 3 eastward flights from the U.S. east coast, were estimated to be 2.0 ± 1 .5% hour1. Measurements near Bermuda were in marine air with average mixing ratios near the surface of 0.8 ppbv for NOy and 0.3 ppbv for total N03\ No significant vertical gradient was observed for NOy near Bermuda, where the high-altitude NOy mixing ratio was 0.7 ppbv. Overall, NOy mixing ratios near Bermuda were higher than would be expected on the basis of either measurements or computer modeling for remote marine air, suggesting possible influence from local anthropogenic sources. 35 AR-101 Ray, J.D., C.C. VAN VALIN, M. Luria, and J.F. BOATMAN. Oxidants in the marine troposphere: H202 and 03 over the western Atlantic ocean. Global Biogeochemical Cycles 4(2):201-214 (1990). Measurements of tropospheric Hj02 and 03 concentrations were made over the Atlantic Ocean near the U.S. east coast (southeast of Newport News, Virginia) and near Bermuda during July 1988 with an instrumented aircraft Oxidant concentrations were high (03 up to 100 parts per billion by volume (ppbv) and H202 up to 2.5 ppbv) near the U.S. east coast at low altitude by decreased rapidly with increasing offshore distance to concentrations comparable to those measured near Bermuda. 03 concentrations observed near Bermuda at low altitude were 14-22 ppbv, comparable to those reported for remote subtropical marine locations. 03 concentrations increased with altitude (up to 2.6 km); high-altitude concentrations were 30-80 ppbv. H202 concentrations near Bermuda varied by a factor of 2, 0.7-1.5 ppbv, from day to day, but were nearly constant at all altitudes during individual flights. Because a high-pressure system centered over the western Atlantic Ocean limited eastward advection of continental air toward Bermuda, these concentrations are assumed to be typical of mid-latitude marine air during summer. AR-102 Robinson, P.G., and P.L. FINKELSTEIN. The development of impact-oriented climate scenarios. Bulletin of the American Meteorological Society 72:481-490 (1991). Appropriate scenarios of future climate must be developed prior to any assessment of the impacts of climate change. Information needed was examined in consultation with those having experience in scenario use. Most assessors require regional scenarios with a temporal resolution of one day and a spatial resolution of around 100 km. Scenarios should contain one or more of: 1) general descriptive statistics of the major climate elements, 2) information about climatic anomalies such as drought, 3) statistics on the frequency and probability of events exceeding particular thresholds, and 4) general synoptic information. Techniques of climate analysis currently available were reviewed for their suitability to meet these scenario needs. The techniques were divided into a series of modules: groups of similar analysis techniques providing scientifically sound pieces of required information. A series of linked modules then provides the complete scenario. One set of modules emphasizes process models, another set uses empirical analyses. The final set involves linkage between the other two. For each module the needs and opportunities for research directed towards scenario development are discussed. AR-103 ROLPH, G.D., and R.S. ARTZ. A paired comparison of two precipitation chemistry sites in east-central Mississippi. Atmospheric Environment 25A(8) 1449-1461 (1991). A paired comparison was performed on 2 years of precipitation chemistry data from Meridian and Newton, Mississippi. The Meridian site is in violation of several National Atmospheric Deposition Program siting criteria, whereas the Newton site, 35 km west, is mostly in compliance. The two sites are compared through the use of volume-weighted means, deposition, logarithmic distributions, boxplots, paired t tests, the nonparametric Wilcoxon test, and a form of linear regression analysis that accounts for cases in which both populations are subject to error. Results indicate Meridian has higher concentrations of all measured ions except NH, . Elevated NH< concentrations at Newton are most likely due to the location of the site in a cattle pasture. Significant differences (95% confidence level) were found for CI", Na+, K+, Ca2+, Mg2*. SO2,", was found to be borderline significant. AR-104 ROLPH, G.D., and R.R. DRAXLER. Sensitivity of three-dimensional trajectories to the spatial and temporal densities of the wind field. Journal of Applied Meteorology 29(10): 1043-1054 (1990). Initialization and forecast fields from the National Weather Service's (NWS) Nested Grid Model (NGM) were archived on the 90 km calculational grid at 2-hour intervals out to 12 hours, twice per day, for the 3-month period of January-March 1987. The resulting time series of meteorological data were used to determine the sensitivity of calculated trajectories to changes in temporal and spatial density of meteorological data during a wide range of synoptic conditions. Trajectories were started from 63 evenly spaced locations, twice per day, for a duration of 4 days each over the 74-day period. The 9324 separate trajectories were computed using the meteorological data at 90, 180, and 360 km grid spacing and at 2-, 4-, 6-, and 12-hour time intervals. Calculated trajectories were compared with the base "truth" case of 2-hour data on the 90 km grid. Trajectories were most sensitive to changes in temporal resolution when the grid resolution was 90 and 180 km. Trajectories computed on the coarser 360 km grid had substantially larger deviations from the base case and were no longer sensitive to changes in temporal resolution. Relative horizontal transport deviations ranged from 5-25% of the travel distance at 96 hours depending upon the spatial and temporal resolution. Results suggest that if rawinsonde observations are the primary source of meteorological data (400 km spacing every 12 hours), then the greatest improvement in trajectory accuracy can be achieved by enhancing the temporal frequency of observations to 6-hour intervals. Results were not different when trajectories were categorized by cyclonic or anticyclonic conditions. However, horizontal deviations during cyclonic conditions were as much as 30% larger than those during anticyclonic conditions. This was attributed primarily to stronger wind speeds in cyclonic systems. 36 AR-105 ROSELLE, S.J., T.E. PIERCE, and K.L. SCHERE. The sensitivity of regional ozone modeling to biogenic hydrocarbons. Journal of Geophysical Research 96(D4):7371-7394 (1991). The sensitivity of regional ozone concentrations to biogenic hydrocarbons in the northeastern United States has been examined using an Eulerian grid photochemical model having a horizontal resolution of 18 km. A 6-day period during which observed ozone concentrations exceeded 200 ppb was simulated. Detailed estimates of biogenic nonmethane hydrocarbon (NMHC) emissions were included in the model simulations. Overall, biogenic emissions were of the same order of magnitude as anthropogenic emissions. Approximately 33 % of the biogenic inventory was in the form of isoprene, with the remainder of the NMHC in the form of monoterpenes and unidentified NMHC. Three model sensitivity runs were analyzed in which biogenic emissions, and then anthropogenic hydrocarbon emissions, were selectively removed from the emissions data set. Episode maximum predicted ozone concentrations were compared for each simulation, and a detailed chemical analysis was performed on two trajectories within the modeling domain. The analysis showed that the relative impact of biogenic compared to anthropogenic hydrocarbons on ozone generation varied spatially over the model domain. The biogenic influence on ozone was greatest in western and southern sections of the domain, particularly in the Ohio Valley, while the anthropogenic influence was greatest in the urbanized Northeast Corridor and industrial Great Lakes area. AR-106 Roth, P.M., S.D. Reynolds, T.W. Tesche, and R.L. DENNIS. A conceptual framework for evaluating the performance of grid-based photochemical air quality simulation models. Preprints, 19th International Technical Meeting of NATO/CCMS on Air Pollution Modelling and its Applications, Volume II, Ierapetra, Crete, Greece, September 29-October 4, 1991. NATO/CCMS, Brussels, Belgium, 631-637(1991). No abstract. AR-107 Schaller, E., J.S. Chang, J. BOATMAN, J.K.S. CHING, M. Meyer- Wyk, J.E. PLEJM, and C.W. Spicer. Evaluation of RADM predictions for a mesoscale-j3 box volume over northeastern Pennsylvania. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 50-53 (1991). Extended abstract. AR-108 Sherwood, S.I., D.F. Gatz, R.P. HOSKER, JR., C.I. Davidson, B.B. HICKS, R. Linzey, E.S. McGee, R.L. Schmiermund, D.A. Dolske, D. Langmuir, F.W. Lipfert, V.G. Mossotti, and E.C. Spiker. Processes of Deposition to Structures. Acidic Deposition: State of Science and Technology Report 20. National Acid Precipitation Assessment Program, Washington, DC, 20-1 - 20-146 (1990). No abstract. AR-109 Sievering, H., J. BOATMAN, J. Galloway, W. Keene, Y. Kim, M. Luria, and J. Ray. Heterogeneous sulfur conversion in sea-salt aerosol particles: The role of aerosol water content and size distribution. Atmospheric Environment 25 A(8): 1479-1 487 (1991). Meteorological and chemical conditions during the July 1988 Bermuda-area sampling appear to have been favorable for conversion of sulfur gases to particulate excess sulfate (XSOJ. Observed average XS04 and S02 concentrations of 1 1 and 2.1 nmol m~3, respectively, at 15 m a.s.l. in the marine boundary layer (MBL) upwind of Bermuda, indicate that conversion of SOj to XS04) over and above homogeneous conversion, may be necessary to explain the > 5 .0 average molar ration of XSO, to SOj . Given an observed cloud cover of < 15% over the region and the <3 nmol m3 S02 concentrations observed by aircraft, heterogeneous conversion mechanisms, in addition to cloud conversion of S02, are necessary to explain the observed 1 1 nmol XS04 m'3. Aerosol water content, estimated as a function of particle size distribution plus consideration of S02 mass transfer for the observed particle size distribution, shows that S02 was rapidly transferred to the sea-salt aerosol particles. Assuming that aqueous-phase S02 reaction kinetics within the high pH sea-salt aerosol water controlled by 03 oxidation, and considering mass-transfer limitations, S02 conversion to XSO< in the sea-salt aerosol water occurred at rates of approximately 5 % h'1 under the low S02 concentration, Bermuda-area sampling conditions. All of the 2 nmol XS04 m~3 associated with sea-salt aerosol particles during low-wind-speed, Bermuda-area sampling can be explained by this conversion mechanism. Higher wind speed, greater aerosol water content and higher S02 concentration conditions over the North Atlantic are estimated to generate more than 4 nmol XS04 m"3 by heterogeneous conversion of SO, in sea-salt aerosol particles. 37 AR-110 Sievering, H., G. Ennis, E. Gorman, and C. NAGAMOTO. Size distributions and statistical analysis of nitrate, excess sulfate, and chloride deficit in the marine boundary layer during GCE/CASEAVATOX. Global Biogeochemical Cycles 4(4):395-405 (1990). A high-volume sampler and a two-stage cascade impactor were used aboard the NOAA ship Mt, Mitchell to obtain a fine-particle- fraction and two coarse-particle-fraction size cuts of atmospheric marine boundary layer aerosol samples. Ion chromatography analysis yielded NOy, SO,,., Na + , and Cr concentrations and, by calculation, excess sulfate (XSOJ and chloride deficit (CI,,) concentrations. Statistical analysis of the July 1988 sample sets from the Bermuda and U.S. east coast areas showed that most of the observed coarse- particle Cld in the Bermuda-area samples may be associated with the equivalence sum of NOy and XS04. However, the coarse-particle Cld observed in the U.S. east coast samples is substantially greater than the equivalence sum of N03 and XS04 observed at this location. It is concluded that for the east coast sampling, about 13% of the observed 16.9 nmol XS04 m3 displaced CI in sea salt aerosol particles. For the Bermuda area, 15-20% of the observed 11.1 nmol XS04 m3 displaced CI in sea salt aerosol particles (nearly 30% of the observed CLJ despite a relatively low sea salt mass concentration under light wind speed conditions. Under more typical sea state and wind speed conditions for the western North Atlantic Ocean, substantially more XS04 may displace chloride ions in sea salt aerosol particles. AR-111 Sistla, G., S.T. Rao, and J. GODOWTTCH. Sensitivity analysis of a nested ozone air quality model. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 250-255 (1991). Extended abstract. AR-112 SNYDER, W.H., L.W. Khurshudyan, I.V. Nekrasov, R.E. LAWSON, Jr., and R.S. Thompson. Flow and dispersion of pollutants within two-dimensional valleys. Atmospheric Environment 25 A: 1347-75 (1991). Wind tunnel experiments and a theoretical model concerning the flow structure and pollutant diffusion over two-dimensional valleys of varying aspect ratio are described and compared. Three model valleys were used, having small, medium, and steep slopes. Measurements of mean and turbulent velocity fields were made upstream, within and downwind of each of these valleys. Concentration distributions were measured downwind of tracer sources placed at an array of locations within each of the valleys. The data are displayed as maps of terrain amplification factors, defined as the ratios of maximum ground-level concentrations in the presence of the valleys to the maxima observed from sources of the same height located in flat terrain. Maps are also provided showing the distance to locations of the maximum ground-level concentrations. The concentration patterns are interpreted in terms of the detailed flow structure measured in the valleys. These data were also compared with results of a mathematical model for treating flow and dispersion over two-dimensional complex terrain. This model used the wind tunnel measurements to generate mean flow fields and eddy diffusivities, and these were applied in the numerical solution of the diffusion equation. Measured concentration fields were predicted reasonably well by this model for the valley of small slope and somewhat less well for the valley of medium slope. Because flow separation was observed within the steepest valley, the model was not applied in this case. AR-113 Spicer, C.W., T.J. Kelly, J. Chang, J.K.S. CHING, R.L. DENNIS, E. Schaller, K. Busness, R. Lee, C. Lindsey, and J. Anderson. Diagnostic evaluation of Regional Acid Deposition Model (RADM) performance during a period of frontal passage using aircraft measurements. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 139-142 (1991). Extended abstract. AR-114 START, G.E. Planning and managing a field operations center for the collaborative SJVAQS and AUSPEX field study. Proceedings, 84th Annual Meeting of the Air & Waste Management Association, Vancouver, B.C., Canada, June 16-25, 1991. Air & Waste Management Association, Pittsburgh, A&WMA 91-71.3 (1991). The joint SJVAQS and AUSPEX field study was designed to occur within a large geographical area in central California and involve the intense activities of several hundred personnel within a three month period. An extensive management capability was required to coordinate contractor activities over the two month measurement window. Contractors for both routine ground-based monitoring programs and for intensive days of extensive aerosol, aircraft, gaseous tracer, and upper air meteorological measurements required planning and coordinating information on a day to day basis. This paper summarizes the functions planned and implemented at the centralized field operations center (FOC) in Fresno. The staff of the FOC, under the direction of the Field Program Manager, provided coordination with 38 individual contractor organizations, personnel operating measurement platforms, project principal investigators (Pis), addressed facility and resource problems at remote field measurement sites, provided emergency communications and logistics support. Special FOC functions included the coordinated forecast support for daily and weekly planning of intensive operations, coordination between this study and other concurrent research programs, and daily briefings of the program management and the Pis. The methods selected to implement those functions, the successes and the weaknesses of them, and recommendations for future programs are presented. AR-115 Stauffer, D.R., N.L. Seaman, and F.S. BINKOWSKI. Use of four-dimensional data assimilation in a limited-area mesoscale model. Part II: Effects of data assimilation within the planetary boundary layer. Monthly Weather Review 1 19:734-754 (1991). A four-dimensional data assimilation (FDD A) scheme based on Newtonian relaxation or nudging has been developed and evaluated in the Pennsylvania State University/National Center for Atmospheric Research (PSU/NCAR) Limited- Area Mesoscale Model. It was shown in Part I of this study that continuous assimilation of standard-resolution rawinsonde observations throughout a model integration, rather than at only the initial time, can successfully limit large-scale model error growth (amplitude and phase errors) while the model maintains intervariable consistency and generates realistic mesoscale structures not resolved by the data. The purpose of this paper is to further refine the previously reported FDDA strategy used to produce "dynamic analyses" of the atmosphere by investigating the effects of data assimilation within the planetary boundary layer (PBL). The data used for assimilation include conventional synoptic-scale rawinsonde data and mesoalpha-scale surface data. The main objective of this study is to determine how to effectively utilize the combined strength of these two simple data systems while avoiding their individual weaknesses. Ten experiments, which use a 15-layer version of the model, are evaluated for two midlatitude, real-data cases. It is found that the homogenizing effect of vertical mixing during free convective conditions allows the three-hourly surface-layer wind and mixing ratio observations to be applied throughout the model PBL according to an idealized conceptual model of boundary-layer structure. Single-level surface temperature observations, however, are often poorly representative of the boundary layer as a whole (e.g., shallow superadiabatic layers, nocturnal inversions), and are more attractive for FDDA applications when additional vertical profile information is available. Assimilation of surface wind and moisture data throughout the model PBL generally showed a positive impact on the simulated precipitation by better resolving the low-level structure and movement of systems (e.g., cyclones, fronts) during the 12-h periods bracketed by the standard rawinsonde data. Improved precipitation simulations due to assimilation of surface data are also possible even in cases with weak large-scale forcing, because a significant portion of the vertically integrated moisture convergence often occurs in the boundary layer. Overall, the best dynamic analyses of precipitation, PBL depth, surface-layer temperature, and tropospheric mass and windfields were obtained by nudging to analyses of rawinsonde wind, temperature, and moisture above the model PBL and to analyses of surface-layer wind and moisture within the model PBL. AR-116 Stockton, P.H., and D.A. GILLETTE. Field measurement of the sheltering effect of vegetation on erodible land surfaces. Land Degradation and Rehabilitation 2:77-85 (1990). Natural vegetation on erodible land surfaces, such as the loose sandy soils found in the southwestern United States and in Soviet Central Asia, absorbs part of the wind momentum flux (stress) and thus protects the erodible soil to a degree that depends on the geometry of plant distribution and profile. The sheltering effect of natural plants may be expressed as the ratio, R, of threshold friction velocity for the bare soil (determined in the laboratory or in specially prepared areas of bare soil in the field) to that for the naturally vegetated surface. We used new automated instrumentation to detect erosion thresholds in locations where erosion events are widely separated in time. Measured values of R were low for our most vegetated sites and nearer unity for the sparsely vegetated site. AR-117 STUNDER, B.J.B., R.S. ARTZ, G.D. ROLPH, J.M. HARRIS, and J.T. Merrill. Summary of meteorological conditions over the North Atlantic Ocean during GCE/CASE/WATOX. Global Biogeochemical Cycles 4(2): 133- 150 (1990). During the summer of 1988, a team of scientists aboard the NOAA ship Mt. Mitchell and the NOAA King Air aircraft investigated the spatial distributions of sulfur, nitrogen, and related species and their interactions over the North Atlantic Ocean. In support of these measurements, meteorological data from the National Meteorological Center and from rawinsonde data obtained from the ship were archived and back trajectories were calculated. A summary of the meteorological conditions during the cruise is presented using synoptic maps, soundings, cross sections, and isobaric and isentropic back trajectories. Since day-to-day variability of the synoptic situation was generally small, one representative day was chosen to illustrate the overall meteorology. During the cruise, three synoptic regimes were encountered: (1) north of the polar front, (2) under the Bermuda/Azores high, and (3) under the Intertropical Convergence Zone (TTCZ). Soundings from three different days illustrate these regimes. Boundary layer depth and cloud layers were also estimated from all the soundings. Cross sections of temperature, wind, and relative humidity describing the vertical structure of the atmosphere along the cruise show the general day-to-day uniformity except near the polar front and near the ITCZ boundary. The back trajectories show general air flow patterns and the land mass source regions of air reaching the ship within three days. For parts of the cruise, air reached the ship from North America, Iceland or Greenland, Africa, and South America. 39 AR-118 TOUMA, J.S., and K.T. Stroupe. TSCREEN: A personal computer system for screening toxic air pollutant impacts. Preprints, International Conference and Workshop on Modeling and Mitigating the Consequences of Accidental Releases of Hazardous Materials, New Orleans, LA, May 1991. American Institute of Chemical Engineers, New York, 712-723 (1991). Simplified screening methods for determining maximum short-term impact from various well-defined releases of toxic air pollutants are described in a workbook of screening techniques. These scenarios include continuous and instantaneous emissions from point sources, fugitive emissions, continuous emissions from land treatment facilities and municipal solid waste landfills, evaporation from surface impoundments and liquid leaks from pipes and tanks. TSCREEN is a recently developed computer program that provides, by use of interactive menus and data entry screens, the same steps as the workbook. The correct release scenarios and associated characteristics of a toxic emissions release are selected with the help of on-screen text. Extensive help system, text edit, and graphical display capabilities are provided to guide the user. The purpose of this paper is to describe the capabilities of the TSCREEN model and illustrate the usefulness of its various features. AR-119 TOUMA, J.S., J.G. Zapert, H. Thistle, R.L. Londergan, and R. Topazio. Performance evaluation of air toxics dispersion models for simulating heavier-than-air releases. Preprints, International Conference and Workshop on Modeling and Mitigating the Consequences of Accidental Releases of Hazardous Materials, New Orleans, LA, May 1991 . American Institute of Chemical Engineers, New York, 735-746 (1991). This paper summarizes the approach and presents the results of an evaluation study of seven dense gas simulation models using data from three experimental programs. Two of the models evaluated are in the public domain (DEGADIS and SLAB) and five of the models are proprietary (AIRTOX, CHARM, FOCUS, SAFEMODE, and TRACE). The data bases used in the evaluation are the Desert Tortoise Pressurized Ammonia Releases, Burro Liquefied Natural Gas Spill Tests and the Goldfish Anhydrous Hydroflouric Acid Spill Experiments. Desert Tortoise and Goldfish were simulated as a horizontal jet release, and Burro as a spill. Details of the study are fully described in "Evaluation of Dense Gas Simulation Models," (EPA, 1991). A uniform set of performance statistics are calculated and tabulated to compare maximum observed concentrations to those predicted by each model. None of the models demonstrated good performance consistently for all three experimental programs. AR-120 TURNER, D.B., L.W. Bender, J.O. Paumier, and P.F. Boone. Evaluation of the TUPOS quality dispersion model using data from the EPRI Kincaid Field Study. Atmospheric Environment 25A:2087-2201 (1991). Data form the SFj tracer studies conducted at the Kincaid power plant in central Illinois by the Electric Power Research Institute in 1980 and 1981 have been used to evaluate the TUPOS air quality dispersion model. Most of the 96 h data are from periods representing daytime convective conditions when the impact of an elevated buoyant source would be expected to be greatest at ground level. Since on the order of 200 tracer measurement stations on four to six arcs were in operation during each hour of the study, a reasonable estimate of the maximum concentration along each arc could be made. The maximum concentration on each arc was the principle value used for purposes of comparing tracer measurements with model estimates. In addition to masking comparisons between tracer and TUPOS estimates, comparisons were also made using the regulatory model MPTER. Although the means of residuals (model concentration minus tracer concentration) from the hourly maxima are both negative, TUPOS with a mean residual of -32.6 ppt (parts per trillion) shows improvement over MPTER with a mean residual of - 50.3 ppt. Tracer concentrations show 4 hourly maxima exceed 500 ppt. TUPOS estimates 3 and MPTER estimates 2 concentrations above 500 ppt. The performance results were used to suggest further changes to the TUPOS model. These consisted primarily of determining the fluctuation statistics and windspeed and direction for a height midway between effective plume height and ground level rather than at plume height. These changes were implemented and shown to provide improvement when tested on the dependent data set used to evaluate the original model. The mean of the residuals for hourly maxima for the REVISED TUPOS is -0.2 ppt showing a shift to almost no bias. The REVISED TUPOS estimates 5 hourly maxima exceeding 500 ppt. Although the significance of the results for the revised model are not as great as they would be if an independent data set were used, these results are still useful in indicating the proper direction of changes to be made that can improve modeling. AR-121 van den Hurk, B.J.J.M., and D.D. BALDOCCHI. Random-walk models for simulating water vapor exchange within and above a soybean canopy. NOAA TM ERL ARL-185 (PB91 124487), 48 pp. (1990). The turbulent exchange of mass between a plant canopy and the atmosphere can be modelled with either Eulerian or Lagrangian models. The application of eulerian models for estimating turbulent transfer within and above plant canopies has been criticized because of an inability to treat the dispersion of material from nearby sources well. Lagrangian models do not suffer from this deficiency since they consider the diffusion of material from both nearby and far away sources explicitly. We developed three Lagrangian random walk models for computing the exchange of water vapor and water vapor mixing ratio profiles above and within a plant canopy. The movement of fluid 40 parcels was computed using algorithms presented by Legg and Raupach (1982), Wilson et al. (1983) and Thomson (1984). The source strength of water vapor at discrete layers in the canopy was parameterized from estimates of net radiation flux density. The models were tested against measurements made within and above a soybean canopy. Computed water vapor profiles, based on the algorithms of Legg and Raupach and Wilson et al., agree well with measured water values. However, subtle differences in the performance of these two models occurred. The model based on the Legg and Raupach formulation does a better job of predicting the water vapor concentration field inside the canopy while the model using the Wilson et al. algorithm yields more accurate computations of the mixing ratio profile above the canopy. The Lagrangian model based on the algorithm of Thomson computes water vapor profiles that severely underestimate measured values. The Thomson model, though theoretically rigorous, suffers from limitations in its numerical formulation; small requisite time steps yield a negatively skewed third order moment in the random forcing term, which decreases the accuracy of generating a prescribed distribution of random numbers. We also demonstrate that the validated Lagrangian models are more realistic in estimating water vapor mixing ratio profile inside a plant canopy than the Eulerian models. The Eulerian model does not simulate the counter-gradient transfer of water vapor or the prominent "nose" in the water vapor mixing ratio profile, which occurs because of the superposition of vapor from nesrby sources on those from farther sources. AR-122 van Dop, H., R.L. DENNIS, J.C.R. Hunt, G. Kallos, G. McBean, T.R. Oke, F.A. SCHIERMEIER, and J.D. Shannon. Report on Meeting: 18th International Technical Meeting of NATO-CCMS on Air Pollution Modelling and Its Applications. Atmospheric Environment 25A: 1730-1732 (1990). No abstract. AR-123 Viswanathan, R., M. McGown, J. McElroy, M. PITCHFORD, C. Edmonds, and D. Bundy. Lidar application for estimating relative particulate flux. Preprints, Seventh Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, J217-J218 (1991). Extended abstract. AR-124 Whitby, E.R., P.H. McMurry, U. Shankar, and F.S. BINKOWSKI. Modal aerosol dynamics modeling. EPA/600/3-91/020 (PB91-161 729), Atmospheric Research and Exposure Assessment Laboratory, Research Triangle Park, NC (1991). The governing equations for representing aerosol dynamics, based on several different representations of the aerosol size distribution, are presented. Analytical and numerical solution techniques of these governing equations are also reviewed. Described in detail is a computationally efficient numerical technique for simulating aerosol behavior in systems undergoing simultaneous heat transfer, fluid flow, and mass transfer in and between the gas and condensed phases. The technique belongs to a general class of models known as modal aerosol dynamics (MAD) models. These models solve for the temporal and spatial evolution of the particle size distribution function. Computational efficiency is achieved by representing the complete aerosol population as a sum of additive overlapping populations (modes), and solving for the time rate of change of integral moments of each mode. Applications of MAD models for simulating aerosol dynamics in continuous stirred tank aerosol reactors (CSTARs) and flow aerosol reactors (FARs) using the SIMPLER algorithm (Patankar, 1980) are provided. Considerations for incorporating a MAD model into the U.S. Environmental Protection Agency's Regional Particulate Model are also described. Numerical and analytical techniques for evaluating the size-space integrals of the MDEs for MAD models are described. For multimodal lognormal distributions, an analytical expression for the coagulation integrals of the MDE, applicable for all size regimes, is derived, and is within 20% of accurate numerical evaluation of the same moment coagulation integrals. A computationally efficient integration technique, based on Gauss-Hermite numerical integration, is also derived. Techniques for analytically integrating fin time) a linearized form of the MDEs are presented. These techniques are computationally more efficient than fourth-order Runge-Kutta techniques for situations when global integration errors on the order of 1 % are acceptable. AR-125 Womack, J.D. Description of the National Oceanic and Atmospheric Administration (NOAA) dry deposition research network of monitoring stations. Air pollution and historic monuments in Cracow, US/ICOMOS, Vol. I, R.E. Stipe, (ed.). Report of the U.S. National Park Service Delegation to Poland, Washington, DC, 74-79 (1991). No abstract. 41 AR-126 Womack, J.D., and T.L. CRAWFORD. Description and demonstration of a continuous flow aPCO, monitor. Preprints, Seventh Symposium on Meteorological Observations and Instrumentation and Special Sessions on Laser Atmospheric Studies, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, 34-36 (1991). Extended abstract. AR-127 Yaaqub, R.R., T.D. Davies, T.D. Jickells, and J.M. MILLER. Trace elements in daily collected aerosols at a site in southeast England. Atmospheric Environment 25A(5/6):985-996 (1991). Daily collections of aerosols have been made at a site in southeast England over a 1 year period and the samples analyzed for 13 components including soot carbon, major anions, some major cations and five trace metals (Pb, Cd, Zn, Mn and Ni). The results are consistent with other more limited studies in the southern North Sea and can be used to tentatively identify primary and secondary sources for the components of the aerosol. Elemental ratios for some components derived from anthropogenic sources vary slightly depending on the source region over which the air has recently travelled. Classification of the samples by back trajectory analysis shows that for all components, except those derived from seawater, concentrations are highest in air arriving from the east. This observation is discussed in terms of meteorological control on the transport and deposition of aerosols. Specifically, high pressure over Europe allows the accumulation of pollutants through reduced atmospheric dispersion and limited removal by precipitation. Subsequent long-range transport results in high concentrations of aerosols at the sampling site. By contrast, transport from the west is associated with efficient dispersal and removal processes. Addendum AR-128 Allwine, K.J., R.E. ESKRIDGE, and B.K. Lamb. Night-time winter tracer study in a mountainous basin at Roanoke, Virginia. Preprints, Fifth Conference on Mountain Meteorology, Boulder, CO, June 26-29, 1990. American Meteorological Society, Boston, 202-208 (1990). Extended abstract. AR-129 ANGELL, J.K. Variation in United States cloudiness and sunshine duration between 1950 and the drought year of 1988. Journal of Climate 3(2):296-308 (1990). The variations in United States cloudiness (percent of sky covered by clouds, as estimated subjectively by observers at 100 National Weather Service stations) and sunshine duration (percent of possible sunshine, as estimated objectively by sunshine recorders at these same 100 stations) are examined for years 1950-88. During this period, the correlation between annual values of cloudiness and sunshine duration within the contiguous United States was -0.86 significant at the 1 % level. The years of maximum cloudiness, and minimum sunshine duration, were 1972 and 1982 when strong El Ninos began. The year of maximum sunshine duration was 1988, but the years of minimum cloudiness were 1952-56 (mini dust bowl), the discrepancy a result of the greater long-term increase in cloudiness than decrease in sunshine duration. In the spring of 1988 there were anomalous values of cloudiness (below average) and sunshine duration (above average) in North Central, South Central and Southeast regions of the United States, the deviations from average approaching 10%. In the summer of 1988 these deviations were anomalous only in North Central and Northwest regions. Despite the low cloudiness in 1988, based on this analysis the United States cloudiness increased by 2.0 _+ 1.3% between 1950-68 and 1970-88 (corresponding to a percentage increase of 3.5% since the average cloudiness was 58%, or 5.8 tenths, during 1950-88). The increase in cloudiness was close to 2% in all 6 regions of the country, and significant at the 5 % level in all regions except the Southeast. Most of the increase in cloudiness was in autumn, with a negligible increase in spring. The decrease in United States sunshine duration between 1950-68 and 1970-88 is indicated to be only -0.8 ±_ 1.2%, however (corresponding to a percentage decrease of -1.2% since the average sunshine duration was 63% during 1950-88). The difference between cloudiness increase, and sunshine-duration decrease, is most apparent in the West and may be due in part to an increase in cirrus not thick enough to turn off the sunshine recorder. There has been a correlation of 0.79 (significant at the 1 % level) between annual cloudiness and precipitation within the United States during 1950-88, but the correlation of -0.43 between annual cloudiness and surface temperature (above-average cloudiness associated with below-average temperature) is not quite significant at the 5% level. Considered is the possible relation between the 1987 El Nino and United States cloudiness and sunshine duration. 42 AR-130 BAKER, C.B., R.E. Eskridge, P.S. Conklin, and K.R. Knoerr. A wind tunnel investigation of three sonic anemometers. NOAA TM ERL ARL-178 (PB90149808), 30 pp. (1989). The flow distortion induced by three different sonic anemometer arrays was systematically studied in a wind tunnel. Blockage effects due to the probe arrays in the tunnel were negligible. The sonics were rotated through 190°in the horizontal and _+ 15° in the vertical at three different speeds. It was found that the flow distortion parameterization must be done for the entire probe assembly and that a wind tunnel is necessary to provide the controlled condition necessary to obtain the shape of the response curve for each geometric configuration. The error in the horizontal components of the wind speed was found to be as much as 15%. The estimation of wind direction calculated from the horizontal components has an accuracy of 3°. Momentum flux measurements under convective conditions would be better measured with sonic arrays that have all three components in front of the support arm. AR-131 IRWIN, J.S., and J.O. Paumier. Sonic anemometer measurements within a room. Proceedings, Fifth International Conference on Indoor Air Quality and Climate, Toronto, Canada, July 29-August 3, 1990. Canada Mortgage & Housing Corporation, Ottawa, Ontario, Canada, 391-394 (1990). No abstract. AR-132 Lenschow, D.H., and B.B. HICKS (eds.). Global Tropospheric Chemistry — Chemical Fluxes in the Global Atmosphere. Report of the Workshop on Measurements of Surface Exchange and Flux Divergence of Chemical Species in the Global Atmosphere. Prepared by the National Center for Atmospheric Research, Boulder, CO for the National Science Foundation, the National Aeronautics and Space Administration and the National Oceanic and Atmospheric Administration, 107 pp. (1989). No abstract. AR-133 MATT, D.R., and J.D. Womack. Atmosphere-surface exchange of ozone to a spruce conifer forest: Measured and inferred. In Ozone in the Atmosphere, R.D. Bojkov and P. Fabian, (eds.). A. Deepak Publishing, Hampton, VA, 490-493 (1989). Ozone fluxes to a spruce fir forest were measured using the eddy correlation technique. The measured concentrations, fluxes and deposition velocities exhibited diurnal cycles as expected. The deposition velocities ranged from v^ < 0.1 cm/s during nighttime to daytime values of approximately 0.5 cm/s. Measured results are compared to inferred fluxes and deposition velocities derived from the Dry Deposition Inferential Model. An analysis of measured and inferred deposition velocities showed that vd was overestimated because the inferred cuticular resistance is too small for nighttime-dry canopy conditions. During the daytime, the canopy resistance is underestimated in the afternoon when the trees are expected to show water stress. AR-134 NAPPO, C.J., J. A. Herwehe, and A.M. Thompson. Observations of ozone profiles in the developing convective boundary layer. In Ozone in the Atmosphere. R.D. Bojkov and P. Fabian, (eds.). A. Deepak Publishing, Hampton, VA, 477-480 (1989). Simultaneous profiles of meteorological variables and ozone concentrations were obtained using a tethered-balloon sounding system. Soundings were made approximately once each hour, from before sunrise until about mid-day. Presented here are some sample observations and qualitative interpretations of the temporal variation of ozone profiles in developing convective planetary boundary layers. AR-135 SNYDER, W.H., L.W. Khurshudyan, I.V. Nekrasov, R.E. LAWSON, Jr., and R.S. Thompson. Flow and dispersion of pollutants within two-dimensional valleys. Proceedings, 1990 EPA/AWMA International Symposium on Measurement of Toxic and Related Air Pollutants, Raleigh, NC, April 29-May 3, 1990. U.S. Environmental Protection Agency, Research Triangle Park, NC, and Air & Waste Management Association, Pittsburgh, 893-897 (1990). Wind-tunnel experiments and a theoretical model concerning the flow structure and pollutant diffusion over two-dimensional valleys of varying aspect ratio are described and compared. Three model valleys were used, having small, medium, and steep slopes. Measurements of mean and turbulent velocity fields were made upstream, within and downwind of each of these valleys. Concentration distributions were measured downwind of tracer sources placed at an array of locations within each of the valleys. The data are displayed as maps of terrain amplification factors, defined as the ratios of maximum ground-level concentrations in the presence of the valleys to the maxima observed 43 from sources of the same height located in flat terrain. Maps are also provided showing the distance to locations of the maximum ground- level concentrations. The concentration patterns are interpreted in terrhs of the detailed flow structure measured in the valleys. These data were also compared with results of a mathematical model for treating flow and dispersion over two-dimensional complex terrain. This model used the wind-tunnel measurements to generate mean flow fields and eddy diffusivities, and these were applied in the numerical solution of the diffusion equation. Measured concentration fields were predicted reasonably well by this model for the valley of small slope and somewhat less well for the valley of medium slope. Because flow separation was observed within the steepest valley, the model was not applied in this case. 44 ATLANTIC OCEANOGRAPHIC AND METEOROLOGICAL LABORATORY AO-001 ABERSON, S.D., and M. DEMARIA. A nested barotropic hurricane track forecast model (V1CBAR). Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 81-86 (1991). No abstract. AO-002 Baik, J. -J., M. DEMARIA, and S. Raman. Observational evidence for upper tropospheric asymmetric eddy momentum forcing and subsequent hurricane intensity change. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 478-481 (1991). No abstract. AO-003 Barnes, G.M., J.F. GAMACHE, M.A. LeMone, and G.J. Stossmeisler. A convective cell in a hurricane rain- band. Monthly Weather Review 1 19(3) : 776-794 (1991). On 10 October 1983 the two NOAA WP-3D aircraft completed a mission designed to provide airborne Doppler radar data for a convective cell embedded in a weak rainband on the trailing side of Hurricane Raymond. Comparisons of the wind field produced from the pseudo-dual-Doppler radar technique with in-situ wind measurements suggest that the larger convective-scale features may be resolved if the sampling time is kept to a minimum. The convective cell was found to move downband faster than any environmental winds, but slightly slower than the winds found in the reflectivity core that delineates the cell. In the core of the cell the tangential wind is increased and the radial inflow turns to outflow with respect to the circulation center. The flow field demonstrates that the downband stratiform portion of a rainband is not from cells currently active, since the updraft detrains upwind relative to the cell, but rather it is due to the fallout from ice particles placed into the upper troposphere by clouds that have since dissipated. The mass flux of this cell is estimated to be 59©-10% of the mass flux accomplished by an eyewall of a moderate tropical cyclone. This finding sup- ports the concept that large, convectively active rainbands have a major effect on the subcloud layer air flowing toward the eyewall. AO-004 Barnes, G.M., and M.D. POWELL. The inflow thermodynamics of Hurricane Gilbert. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 486-489 (1991). No abstract. AO-005 Beryulev, G.P., P.G. BLACK, and A.V. Litinetsky. Iniercomparison of wind and temperature data from the research aircraft WP-3D and AN-12BC in Hurricane Gilbert, 1988. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society. Boston, 587-588 (1991). No abstract. AO-006 BLACK, M.L., R.W. BURPEE, and F.D. MARKS, JR. Vertical motions in tropical cyclones determined with airborne Doppler radial velocities. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 409-411 (1991). No abstract. 45 AO-007 BLACK. P.G., and F.D. MARKS, JR. The structure of an eyewal] meso-vortex in Hurricane Hugo (1989). Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 579-582 (1991). No abstract. AO-008 Bosart, L.F., and J. A. Bartlo. Tropical storm formation in a baroclinic environment. (Research supported by NOAA Grant NA-85-WCC-06191 . ) Monthly Weather Review 119(8) : 1979-2013 (1991). An analysis is presented of the large-scale conditions associated with the initial development of Tropical Storm Diana (September 1984) in a baroclinic environment. Ordinary extratropical wave cyclogenesis began along an old frontal boundary east of Florida after 0000 UTC 7 September and culminated in tropical cyclogenesis 48 h later. Water- vapor satellite imagery showed that the initial cyclogenesis and incipient tropical storm formation was nearly indistinguish- able from a classical midlatitude development. Cyclogenesis occurred in three stages. A large-scale cold trough and associated frontal system crossed the Atlantic coast, while a small potential vorticity maximum aloft fractured off the main trough and stalled over central Florida in the first stage. As the main trough sheared off eastward, cyclogenesis began along the southwestern end of the stalled frontal zone east of Florida. Anticyclogenesis to the north in the wake of the shearing trough allowed a surge of cooler and drier air to flow southeastward behind the front toward the developing cyclone. Combined surface sensible and latent heat fluxes in excess of 1000 W m"2 acted on this inflowing air, pro- ducing a warming and moistening of the boundary layer. Cyclogenesis intensified during the second stage in response to positive potential vorticity advection aloft ahead of the slow moving cutoff cyclone over Florida. The maximum ascent was centered near 300 mb, indicative of deep tropospheric ascent and cyclonic vorticity production by convergence in midlevels. The ascent occurred along uplifted isentropic surfaces that defined the cold dome associated with the potential vorticity anomaly aloft. Low-level potential vorticity was generated in the vicinity of the developing storm below the presumed level of maximum diabatic heating. The third stage of cyclogenesis was marked by the collapse of the mid- and upper tropospheric cold dome and associated potential vorticity maximum and the simultaneous initiation of a warm thickness ridge. This occurred in response to the widespread outbreak of convection at the southwestern end of the baro- clinic zone, where the greatest destabilization occurred for air parcels subject to prolonged surface sensible and latent heat fluxes in the persistent northeasterly flow. Upright ascent associated with the convection short-circuited the slantwise ascent ahead of the advancing potential vorticity anomaly, triggering warming aloft and the eventual disappearance of the potential vorticity anomaly and associated cold dome. Tropical storm development and intensification occurred as the low-level vorticity center (potential vorticity maximum) moved northwestward to become situated beneath the midlevel vortex embedded within a local 500-200 mb warm thickness anomaly. The interaction of the upper and lower level poten- tial vorticity anomalies appeared to be important in the initial strengthening of the tropical cyclone. The interpretation is equivalent to earlier energetic arguments by Riehl and others that tropical cyclogenesis is often preceded by the collapse of a nearby cold dome. AO-009 BURPEE, R.W. Radar characteristics of hurricanes. In Federal Meteorological Handbook No. 11, Doppler Weather Radar Observations. Part B: Radar meteorology and theory. Federal Coordinator for Meteorological Services and Supporting Research, Washington, D.C., 9-1 to 9-14 (1990). No abstract. AO-010 BURPEE, R.W., and P.G. BLACK. Strong surface winds and mesoscale convective systems in the unnamed tropi- cal storm of 1987. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 412-415 (1991). No abstract. AO-011 BURPEE, R.W., J.S. GRIFFIN, J.L. FRANKLIN, and F.D. MARKS, JR. Airborne analysis of observations from a NOAA P-3 in support of operational hurricane forecasting. Preprints, 7th International Conference on Interactive Information and Processing Systems for Meteorology, Oceanography and Hydrology, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, 195-197 (1991). No abstract. 46 AO-012 BURPEE, R.W., J.S. GRIFFIN, J.L. FRANKLIN, and F.D. MARKS, JR. Airborne analysis of observations from a P-3 aircraft in support of operational hurricane forecasting. Proceedings, 4th Interagency Airborne Geoscience Workshop, La Jolla, CA, January 29-February 1, 1991. NASA, Washington, D.C., 123-124 (1991). No abstract. AO-013 Carey, A.G., Jr., D.L. Stein, and P. A. RONA. Benthos of the Gorda Ridge axial valley (northeast Pacific Ocean): Taxonomic composition and trends in distribution. Progress in Oceanography 24:47-57 (1990). Distribution and relative abundance of invertebrate mega-epifauna and benthos fishes were studied in the Gorda Ridge central rift valley off southern Oregon and northern California, USA. Faunal distribution and relative abundance were correlated with location, geological setting, substrate type, and depth. Bottom photographs and videotapes were from 1985-1986 cruises by the U.S. Geological Survey and the U.S. National Oceanic and Atmospheric Administration. Voucher specimens were collected by rock dredge, fish trap and the Deep Submergence Vehicle (DSV) Sea Cliff. Loca- tion, rather than substrate, appears to have more effect on the overall taxonomic composition of the mega-epifauna in the northern and southern parts of the rift valley. Within each location, substrate type, i.e., soft sediments and rock outcrops, and percentage cover of these substrates appear to influence the existing faunal composition. Characteristic fauna are associated with each substrate type, e.g., crinoids, gorgonians and sponges (Demospongiae) on rocky surfaces. In the southern sedimem-filled Escanaba Trough, deposit-feeding organisms, particularly ophiuroids, asteroids and holo- thuroids, are interspersed with stalked suspension feeders, such as hexactinellid sponges and pennatulids. Epifaunal community structure in the northern and southern sectors differ, even on similar substrate combinations. Except for the ubiquitous macrourids, fish species distributions may be correlated with substrate type. Abundant particulate material in the bottom water layer probably accounts for large concentrations of suspension and detritus feeding epibenthos. AO-014 DAMMANN, W.P., J.R. PRONI, J.F. CRAYNOCK, and R. Fergen. Oceanic wastewater outfall plume charac- teristics measured acoustically. Chemistry and Ecology 5:75-84 (1991). A study, called SEFLOE, of the dispersion characteristics of several wastewater outfalls was conducted off of the coast of southeast Florida (USA). In this study, the feasibility of utilizing high frequency (20 kHz and 200 kHz) acoustic echoes to characterize the dilution characteristics of the effluent wastewater was examined. It is hypothesized that the background corrected acoustic backscattered intensity may be used to guide chemical/biological sampling, and that one or more plume subfields may be revealed by the scattering strength field. Data from SEFLOE have indicated that the waste- water plume field is divided into regions of higher concentration spatially separated by regions of lower concentration; we call these regions of higher concentration "boluses." When the water column is density stratified, subsurface plumes may peel off of the main rising plume and remain at equilibrium on a density gradient. AO-015 DEMARIA, M. Normal mode initialization in a tropical cyclone model. Journal of the Atmospheric Sciences 118(10):2199-2214 (1990). The effect of nonlinear normal mode initialization (NMI) on tropical cyclone simulations is investigated using a three-layer axisymmetric model. It is shown that the balance condition proposed by Machenhauer, which neglects the time tendencies of the gravity-mode amplitudes, is valid in a tropical cyclone simulation. The boundary layer friction, adiabatic nonlinear and diabalic heating terms are important in the balance. A highly truncated version of the model with linearized physical parameterizations is used to analyze the convergence properties of several iterative schemes developed to solve the initialization equations. When diabatic heating is neglected, the schemes will always converge if the linear friction coefficient a is smaller than the Coriolis parameter /. For small horizontal-scale modes, the iterative schemes will also converge for values of a much larger than /. When diabatic heating is included, the rate of convergence of the small horizontal-scale modes becomes extremely slow. The schemes are also tested in the nonlinear version of the model by first running a 7-day tropical cyclone simulation. The initialization schemes are applied at day 5 after the model has produced an intense tropical cyclone. Results show that the tropical cyclone rapidly weakens relative to the uninitialized run during the 6-12 h after the NMI is applied. This weakening occurs because the small horizontal-scale modes do not converge, making the secondary radial circulation much too weak. A scheme is proposed where the NMI is followed by a short integration with the geostrophic modes held fixed. This procedure compensates for the lack of convergence of the small horizontal-scale gravity modes. 47 AO-016 DEMARIA. M., and J. KAPLAN. A statistical model for predicting tropical cyclone intensity change. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society. Boston, 521-525 (1991). No abstract. AO-017 DODGE. P.P.. R.W. BURPEE, and F.D. MARKS, JR. Airborne Doppler radar analyses of the core of Hurricane Gilbert. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 551-552 (1991). No abstract. AO-018 ENFIELD, D.B. Book review, "Study in Geophysics: Sea Level Change." Bulletin of the American Meteorological Society 72:1282-1283 (1991). No abstract. AO-019 ENFIELD, D.B. Statistical analysis of El Nino/Southern Oscillation over the last 500 years. TOGA Notes 1:1-4 (1990). No abstract. AO-020 FEUER, S.E., and J.L. FRANKLIN. Nested analyses of Hurricane Gloria from dropwindsonde and Doppler radar data. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 130-133 (1991). No abstract. AO-021 FRANKLIN, J.L. Dropwindsonde observations of the environmental flow of Hurricane Josephine (1984): Relation- ships to vortex motion. Monthly Weather Review 1 18(12) :2732-2744 (1990). Omega dropwindsonde (ODW) observations from three synoptic-flow experiments in the environment of Hurricane Josephine have been analyzed in a research mode using an objective analysis procedure. The nominal times of the anal- yses are 0000 UTC, 10, 11, and 12 October 1984. The filtered, three-dimensional analyses have been used as a basis for several diagnostic and prognostic calculations relating to the motion of the hurricane. Examination of Josephine's environment revealed a strong variability of the flow with distance from the storm center and with pressure. Josephine moved at right angles to the azimuthally averaged wind at 500 mb; the vortex motion was more consistent with the flow near 700 mb. Forecasts made with a barotropic forecast model showed a high sensitivity of the forecast track to the ver- tical layer used in the initial analysis. These results demonstrate the potential value of vertical sounding information from the ODWs and show that single-level midtropospheric information is not always representative of a hurricanes 's environ- ment flow. On each of the three days, the motion of Josephine deviated significantly from its environmental "steering" as measured by an azimuthal average of the 300-850 mb mean flow over the 5°-7° radial band. This deviation from steering (the so-called "propagation" vector) was oriented with components parallel and to the left of the gradient of absolute vorticity in the asymmetric wind field. The magnitude of the propagation was proportional to the strength of the absolute vorticity gradient. These results are consistent with many barotropic modeling studies. AO-022 FRANKLIN, J.L., M. DEMARIA, and C.S. Velden. The impact of Omega dropwindsonde and satellite data on hurricane track forecasts using the VICBAR model. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 87-92 (1991). No abstract. 4X AO-023 Frazel, D.W., and G.A. BERBERIAN. Distributions of chlorophyll and primary productivity in relation to water column structure in the eastern North Atlantic Ocean. Global Biogeochemical Cycles 4(3):241-251 (1990). Latitudinal variations in the megascale (103 km) distribution of biological properties are described in relation to water column structure between 60° and 7°N in the eastern North Atlantic Ocean. Stations were occupied along a meri- dional transect of stations at 20°W in August-September, 1988, during the third leg of the National Oceanic and Atmo- spheric Administration Global Change Expedition. An additional transect to the south (38°N to 7°N) was occupied to extend the total range of latitudinal observations. Chlorophyll a concentrations were highest in the northern latitudes (<2.51 mg m"3), decreasing to >0.2 mg m"3 in the vicinity of the subtropical gyre, south of 40°N. The nitracline was associated with a shoaling of the pycnocline in the northern latitudes. At 7°N, high chlorophyll concentrations (approxi- mately 0.5 mg m"3), and enhanced primary productivity (375.5 mg C m~2 d"1) were associated with a lens of fresh Amazon River Water. AO-024 GALLAGHER, M.S., T.P. CARSEY, and M.L. FARMER. Peroxyacetyl nitrate in the North Atlantic marine boundary layer. Global Biogeochemical Cycles 4(3):297-308 (1990). An automated system utilizing packed column gas chromatography and electron capture detection for the determina- tion of peroxyacetyl nitrate (PAN) is described. The system was calibrated with a cryogenic PAN sublimation device, a molybdenum catalyst, and a chemiluminescent nitric oxide detector. Computer control of the analysis resulted in an ana- lytical precision level of -1%. A total of 1,178 PAN measurements were made from August 6 to September 5, 1988, in the marine boundary layer during the GCE/CASE/WATOX cruise (66°N to 7°N). Overall, PAN concentrations were highest at high latitudes (up to 40 ppt); PAN levels in the lower latitudes of the cruise track were usually <10 ppt. A number of episodes of elevated PAN are described which were characterized by elevated radon concentrations and a dis- cernible diurnal cycle in the PAN concentration. These higher PAN levels are attributed to air masses with some conti- nental influence, and to the enhanced stability of PAN at the cooler temperatures characteristic of the sub-Arctic region. In aged air masses of marine origin, PAN concentrations were significantly less and did not display diel changes; this is interpreted as a measure of the "background" PAN signal. AO-025 Galloway, J.N., W.C. Keene, A. A. P. PSZENNY, D.M. Whelpdale, H. Sievering, J.T. Merrill, and J.F. Boatman. Sulfur in the western North Atlantic Ocean atmosphere: Results from a summer 1988 ship/aircraft experiment. Global Biogeochemical Cycles 4(4):349-365 (1990). To investigate the relative importance of anthropogenic versus marine sources of sulfur in the North Atlantic Ocean troposphere, sulfur species were measured from aircraft, ship, and island-based platforms as part of the Global Change Expedition/Coordinated Air-Sea Experiment/Western Atlantic Ocean Experiment conducted during the summer of 1988. Four synoptic meteorological cases were examined: flow from highly populated North America; lightly populated North America; tropical oceanic regions; and polar oceanic regions. Literature values suggest that 2-10 jumol m~2 day"1 of (CH3)2S are emitted from the ocean to the atmosphere in marine regions associated with the first three synoptic cases. Data from this experiment indicate that 36, 16, and 14 ^mol m"2 day"1, for the highly populated North America, lightly populated North America, and tropical oceanic region synoptic cases, respectively, were deposited to the ocean's surface. Differences between previously estimated natural emissions and calculated deposition suggest that anthropogenic sources of sulfur contribute significantly to sulfur deposition for these cases. The sulfur deposition rate for the polar oceanic region's synoptic case was 20 /jjno] m~2 day"1. Given the larger range of literature values for the corresponding (CHs^S emission rate (1-14 jumol m"2 day-1), however, the relative importance of the non-marine S source is less certain in this case. AO-026 GAMACHE, J.F. Inner core budget studies of Hurricane Norbert (1984). Preprints, 19th Conference on Hurri- canes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 545-550 (1991). No abstract. 49 ao-o:- GAMACHE, J.F., F. Roux, and F.D. MARKS, JR. Comparison of three methods to deduce three-dimensional wind fields in a hurricane with airborne Doppler radar. Preprints, 25th International Conference on Radar Meteorology. Paris. France, June 24-28, 1991. American Meteorological Society, Boston, 462-465 (1991). No abstract. AO-028 GRIFFIN, J.S., R.W. BURPEE. J.L. FRANKLIN, and F.D. MARKS, JR. Preliminary results of airborne analysis of observations in support of operational hurricane forecasting. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 144-147 (1991). No abstract. AO-029 Hansen, A.D.A., R.S. Artz, A. A. P. PSZENNY, and R.E. Larson. Aerosol black carbon and radon as tracers for air mass origin over the North Atlantic Ocean. Global Biogeochemical Cycles 4(2 ): 1 89-199 (1990). We present results from the Global Change Expedition/Coordinated Air-Sea Experiment /Western Atlantic Ocean Experiment (GCE/CASE/WATOX) research cruise conducted from July to September 1988 in the North Atlantic Ocean aboard the NOAA ship Mt. Mitchell. We examine the correlations between measurements of aerosol black carbon (BC, a tracer for combustion emissions), radon 222 (Rn, a tracer for natural emissions from land masses), and calculated isentropic back trajectories from the ship's position during two portions of the cruise that circled the North Atlantic Ocean. The results suggest four distinct categories of origin of the sampled air mass, with trajectories connecting back to different geographical areas: case A, trajectories from inhabited land, with the air mass containing strongly correlated BC and Rn; case B, trajectories from uninhabited (far northern) land, with Rn but little BC; case C, contaminated marine air, with little Rn but moderate BC, correlated with observations of combustion sources (other ships, etc.) in the vicinity; and case D, air masses of remote marine origin, with low BC and low Rn content. The requirements of the trajectory analyses lead to an improved understanding of the transport pathways across the ocean. We conclude that real-time measurements of aerosol black carbon and radon, coupled with timely meteorological analyses, can be a power- ful indicator of air mass origin both retrospectively and during the course of an experiment to assist in the scheduling of other measurements. AO-030 HANSEN, D.V. Subsurface current and temperature patterns in the western tropical Pacific. Proceedings, U.S.-PRC International TOGA Symposium, Beijing, China, November 15-17, 1988. China Ocean Press, Beijing, 121-127 (1990). No abstract. AO-031 HANSEN, D.V., and G.A. MAUL. Anticyclonic current rings in the easlern tropical Pacific Ocean. Journal of Geophysical Research 96(C4) ;6965-6979 (1990). Observations from satellite-tracked drifting buoys, XBT and CTD data, and GEOSAT altimeter data are used to describe anticyclonic eddies that occur in small numbers off the Pacific coast of Central America. These eddies are simi- lar in many respects to the well-known, warm-core rings that are observed north of the Gulf Stream off the Atlantic coast of North America, except that they occur in an environment that also is warm, and they contain considerably greater kinetic energy. It is hypothesized that they are formed as a result of conservation of potential vorticity when the North Equatorial Countercurrent (NECC) turns northward upon approaching the eastern boundary during its autumnal maxi- mum. The rings so formed have a strongly nonlinear charader which causes them to propagate westward between 9°N and 14°N with a speed in excess of that of long Rossby waves. Due to a relatively small available potential energy con- tent, these rings have a dissipation time scale of about six months and perhaps end by collision with and reabsorbtion into the NECC. The rings account for the observed enhancement of surface kinetic energy, and probably for the seaward transport of waters enriched in copper. 50 AO-032 HARVEY, G.R., and M. SPRINGER- YOUNG. Correction to "Ozone in seawater and lake water: A reversible reservoir." Geophysical Research Letters 18(2):353 (1991). No abstract. AO-033 Hastie, D.R., S. Malle, D.L. Toom, D.M. Whelpdale, W.C. Keene, J.N. Galloway, J. Maben, and A. A. P. PSZENNY. Inorganic nitrogen over the western North Atlantic Ocean. Global Biogeochemical Cycles 4(3):267-278 (1990). The concentrations of the reactive nitrogen species NO2, NOx (=NO + NO2), NOy (the sum of all compounds of nitrogen and oxygen with the exception of N2O), particulate NO3", and volatile NO3", were measured from ship and aircraft platforms over the western North Atlantic Ocean as part of the GCE/CASE/WATOX experiment. Air masses sampled were divided into continentally influenced and typical marine on the basis of trajectories, and radon and black carbon measurements. From the NO3" measurements on size separated aerosol and the altitude variations of volatile NO3' and particulate NO3", a significant interaction between volatile NO3" and sea salt aerosol was indicated. The average marine concentrations measured were: 18 nmol m"3 for NO2, 29 nmol m~- for NOx, 46 nmol m~3 for NOy, and 10 nmol m~3 for total inorganic NO3". The reactive nitrogen species were present at concentrations some 40 times those encountered in the remote Pacific Ocean, where the inorganic NO3" was only three times higher. AO-034 HITCHCOCK, G.L., D.B. Olson, G.A. Knauer, A. A. P. PSZENNY, and J.N. Galloway. Horizontal diffusion and new production in the Sargasso Sea. Global Biogeochemical Cycles 4(4):253-265 (1990). Estimates of vertical particulate carbon flux and inorganic nitrogen input from rain events were evaluated in relation to horizontal diffusion during a short-term (4 days) study in the Sargasso Sea. Productivity (-300 mg C rrr2 d"1) and particulate organic C flux (f-ratio of 0.17) from sediment trap arrays were similar to those recently documented in this region. The drifters traversed the periphery of a small anticyclonic eddy, and an estimate of horizontal diffusivity (~3 to 10 X 104 cm2 s_1) was derived from relative drifter separation. The corresponding length scale (a few kilometers) and time scale (a day) is related to the effective collection area from which drifting sediment traps can sample the surrounding environment. Measurements of inorganic nitrogen from two rain events were similar to those in a more extensive series of observations from Bermuda. The summer Bermuda data are used to evaluate the inorganic nitrogen input to the oligo- trophic surface waters with respect to phytoplankton uptake rates and horizontal diffusion. For small, convective rain events, diffusion may be as important as phytoplankton uptake in reducing nitrogen concentrations to ambient nanomolar levels. AO-035 HOUSTON, S.H., and M.D. POWELL. Effects of Tropical Storm Marco (1990) on Florida's west coast. Preprints, 5th Conference on Meteorology and Oceanography of the Coastal Zone, Miami, FL, May 6-9, 1991. American Meteorological Society, Boston, 131-133 (1991). No abstract. AO-036 JONES, R.W., and M. DEMARIA. A variational method for including persistence in a hurricane track forecast model. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 331-334 (1991). No abstract. AO-037 KAPLAN, J., and J.L. FRANKLIN. The relationship between the motion of Tropical Storm Florence (1988) and its environmental flow. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 93-97 (1991). No abstract. 51 AO-03S Karson, J. A., and P. A. RONA. Block-tilling, transfer faults, and structural control of magmatic and hydrothermal processes in the TAG area, Mid-Atlantic Ridge, 26°N. Geological Society of America Bulletin 102:1635-1645 (1990). Seven Alvin dives (14 km total) and numerous deep-towed camera traverses using ANGUS and NOAA camera systems provide dense coverage of a 12 km2 portion of the eastern wall of the Mid- Atlantic Ridge in the TAG area (26°N latitude). These data, in conjunction with recent Soviet MIR submersible data, provide important constraints on the tectonic, magmatic, and hydrothermal history of this spreading center segment. Active hydrothermal venting occurs near the junction of the median valley floor and eastern median valley wall and appears to be tectonically controlled by the intersection of major fault zones. An east-west fault-line scrap interpreted as an accommodation zone intersects escarpments associated with 020°-trending (ridge-parallel) normal faults that bound the median valley floor. The accom- modation zone permits differential extension and rotation between major crustal blocks to the north and south. On the basis of the distribution of tilted chalk beds and geochemical anomalies in sediments, this fault zone has been intermit- tently active for at least 5 x 104 yr. The accommodation zone has apparently provided a conduit of high permeability oriented at a high angle to the ridge axis. Observations and samples from areas surrounding active and inactive vent sites provide evidence for three distinct episodes for hydrothermal outflow driven by separate magmatic events. The geometry of this active system may have implications for the location of hydrothermal systems in active spreading regimes and for massive sulfide exploration in ophiolite terranes. AO-039 Keene, W.C., A. A. P. PSZENNY, D.J. Jacob, R.A. Duce, J.N. Galloway, J.J. Schultz-Tokos, H. Sievering, and J.F. Boatman. The geochemical cycling of reactive chlorine through the marine troposphere. Global Biogeochemical Cycles 4(4):407-430 (1990). Heterogeneous reactions involving sea-salt aerosol in the marine troposphere are the major global source for volatile inorganic chlorine. We measured reactant and product species hypothesized to be associated with these chemical trans- formations as a function of phase, particle size, and altitude over the North Atlantic Ocean during the summer of 1988. Concentrations of HC1 were typically less than 1.0 ppbv near the sea surface and decreased with altitude and with dis- tance from the U.S. east coast. Concentrations of CI volatilized from aerosols were generally equivalent to the corre- sponding concentrations of HC1 and ranged from less than detection limits to 125 nmol m-3 STP. Highest absolute and percentage losses of particulate CI were typically associated with elevated concentrations of anthropogenic combustion products. Concentrations of product nss SO42" and NO3" in coarse aerosol fractions indicate that, on average, only 38% of measured CI- deficits could be accounted for by the combined effects of acid-base desorption and reactions involving nonacidic N gases. We hypothesize a mechanism for the CI loss initiated by reaction of O3 at sea-salt aerosol surfaces, generating CI2, followed by rapid photochemical conversion of CI2 to HC1 via CI atoms (CI- ) and eventual recapture of HC1 by the aerosol. Simulations with a zero-dimension (0-D) photochemical model suggest that oxidation by CI- may be an important tropospheric sink for dimethyl sulfide and hydrocarbons. Under low NOx conditions, the rapid cycling of reactive CI would provide a catalytic loss mechanism for O3, which would possibly explain the low O3 concentrations often observed above the world's oceans. AO-040 Kumar, M., and G.A. MAUL (editors). Marine Positioning into the 1990's. PIP Publishing, Rockville, MD, 593 pp. (1991). The International Symposium on Marine Positioning (INSMAP '90) was the first quadrennial effort after its prede- cessor held in 1986. It attracted a broad spectrum of national and international scientists, focused stimulating discussions on a wide arena of subjects, and drew attention to many challenging tasks and research topics ahead. INSMAP '90's technical success was hailed unanimously, and its next link in 1994 is eagerly awaited. Our special thanks are expressed to the U.S. Geological Survey; Charting and Geodetic Services, NOAA/NOS; Institute of Naval Oceanography; and the Naval Oceanic and Atmospheric Research Laboratory for their support through financial grants as partial funding to INSMAP '90. We are also grateful to the Rosenstiel School of Marine and Atmospheric Science, University of Miami, for their support and providing the auditorium in making the symposium a success. Over one hundred persons attended INSMAP '90, of which about half were from outside the United States. Twelve technical sessions and five workshops were held within a five-day format. These proceedings contain the written version of the talks, presentations, and reports as submitted by the authors or workshop chairpersons. A few papers have also been included (with appropriate remarks) which were submitted but could not be presented at the INSMAP '90 due to last minute exigencies. We acknowledge with gratitude the support and help of all of the committee members, authors, chairpersons, and participants of INSMAP '90, and are very grateful to Dr. Devi Kumar for her effort in editing and organizing these proceedings. 52 AO-041 Lagos, P., D.V. HANSEN, and A. Herman. Climatological atlas of the subsurface thermal structure of the eastern tropical South Pacific Ocean. NOAA TR ERL 444-AOML 34 (NTIS number not yet available), 303 pp. (1991). Monthly climatological maps of objectively analyzed fields of temperature are presented at standard oceanographic observation levels from the surface to 300 m depth on a 1° latitude-longitude grid in the region between the equator and 20°S and between the South American coast and 90°W. The temperature data used in this study were from bathy- thermograph measurements obtained from 1952 to 1987 from Peruvian and other research vessels; they were made avail- able by research institutions in Peru and the United States and by the National Oceanographic Data Center and the Fleet Numerical Oceanographic Center. The data set was blended with recent data to form a data base containing 14,000 observations. The method of analysis consists of optimally interpolating the value at each mapping grid point, using observations taken at known nearby locations. This method, known as Kriging, is a best linear unbiased estimator that also yields an estimate of the uncertainty of each interpolated value. A brief discussion of the major characteristic features of the temperature fields is given, including a comparison of the SST results with results from other SST clima- tologies. AO-042 Lee, W.-C, and F.D. MARKS, JR. Real-time display of mean 3-D hurricane structure using the VTD technique. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 470-473 (1991). No abstract. AO-043 Lee, W.-C, F.D. MARKS, JR., and R. Carbone. Real-time display of mean 3-D hurricane structure using the VTD technique. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 445-450 (1991). No abstract. AO-044 Lhermitte, R., and P.T. WILLIS. Small Doppler radar as a precipitation gauge. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 790-792 (1991). No abstract. AO-045 MARKS, F.D., JR., D. Atlas, and P.T. WILLIS. Probability matched Z-R relations for hurricanes from aircraft observations. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston. 778-781 (1991). No abstract. AO-046 MARKS, F.D., JR., and R.A. Houze, Jr. Kinematic structure of the eyewall of Hurricane Emily (1987) as deter- mined from an airborne Doppler radar. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 437-440 (1991). No abstract. AO-047 MAUL, G.A. INSMAP '90: The Second International Symposium on Marine Positioning. Bulletin Geodesique 65(l):3-4 (1991). No abstract. 53 AO-04S MAUL. G.A.. S.R. Baig, and M. BUSHNELL. Nowcasling cross-stream profiles of ocean surface current in the Straits of Florida. Journal of Atmospheric and Oceanic Technology 8(1): 179-185 (1991). Cross-stream profiles of ocean surface currents between Florida and the Bahamas are highly correlated with the cross-stream averaged current. When the cross-stream averaged speed is high, the speed axis of the Florida Current is to the west, and when the cross-stream averaged speed is low, the speed axis is near the center of the Straits. Since sea level and weather along the Florida coast are routinely used to nowcast cross-stream averaged speed, nowcasls of cross- stream surface current profiles and location of the speed axis can also be routinely reported. An improved algorithm using cross-stream sea level difference and local weather, and a description of the revised NOAA Gulf Stream product from the National Hurricane Center, are presented. AO-049 MAUL, G.A.. and K. Hanson. Interannual coherence between North Atlantic atmospheric surface pressure and composite southern United States sea level. Geophysical Research Letters 18(4) :653-656 (1991). Annual mean sea levels along the southern United States have been examined for interannual variability. Fifteen sea level stations from Cape Hatteras to the Rio Grande that best covered the three lunar nodal cycles from 1931-1987 were selected for analysis. Linear trends, ranging from +0.2 cm/yr to +1.4 cm/yr, were subtracted from their respective series, leaving remarkably similar residuals. The composite time series of the 15 residuals was compared with time series of surface air pressure over the North Atlantic Ocean during the period 1947-1987. The best correlation is a negative relationship between composite sea level and wintertime air pressure north of 45°N, and a positive relationship from 20°N- 45°N. The most significant correlations (-0.73 and +0.51) were found for 60°N, 20°W and for 30°N, 25°W, respectively. Wintertime meridional air pressure gradients between these two latitudes represents about 50% of the vari- ance in composite annual mean sea level. Both the sea level and air pressure time series had significant spectral peaks at 13.3 and 4.4 years, with about 52% of the covariance coming from these two periods. AO-050 MAUL, G.A., K. Hanson, and H.F. BEZDEK. A note on determining potential anthropogenic signals in sea level: An example from Florida and juxtaposed areas. In Towards an Integrated System for Measuring Long Term Changes in Global Sea Level, H.F. Eden (ed.). Joint Oceanographic Institutions, Inc., Washington, D.C., 17-25 (1990). No abstract. AO-051 MAYER, D.A., and G.A. MAUL. Refinement of the statistical relationship between Straits of Florida sea level difference and Florida-Bahamas cable voltages. Journal of Geophysical Research 96(C3) :4971-4972 (1991). Analyses of a composite 6.5-year record of Bahamas minus Miami sea level difference (SLD) and Florida-Bahamas volume transport determined from submarine cable voltages (CABLE) support the hypothesis advanced by Maul et al. (1990) that SLD is the better variable for monitoring volume transport than western side sea level alone. In the sub- seasonal frequency band BW1 (393_1-1 82_1 cycles per day), modeled CABLE, when using SLD, accounts for 79% of the variance of observed CABLE. Further, the phase relationships of modeled CABLE with respect to SLD in BW1 rep- resent approximately a simple time shift in that SLD leads CABLE by a little more than two weeks. AO-052 MCLEISH, W., and G.A. MAUL. An ocean eddy off Miami. Proceedings, 5th Conference on Meteorology and Oceanography of the Coastal Zone, Miami, FL, May 6-9, 1991. American Meteorological Society, Boston, 94-97 (1991). HF radar maps of ocean surface currents near Miami often show an intermittent counterclockwise eddy between the northward flowing Florida Current and the coast. The maximum average southward speed in the eddy is 20 cm/s at a location near shore, and a typical diameter is 15 km. The eddy develops at times when the offshore current speed decreases and a low speed zone develops near shore. The eddy persists a few days with no propagation detected and dissipates as higher northward speeds near shore return. The development of the eddy, when it occurs, might be caused by flow of the Florida Current past an underwater topographic rise in the continental slope south of Miami. This induces a cyclonic circulation feature extending well into the water and not just a surface phenomenon. A number of earlier studies of the Florida Current consisted of measurements at one or a few locations distributed mostly across the Florida Current but were insufficient to reveal the complete circulation. Although these studies did not hypothesize it, they are 54 consistent with the existence of this intermittent, non-propagating eddy. Similar stationary eddies on a larger scale have been reported in other locations. AO-053 MCLEISH, W., and G.A. MAUL. CODAR in the Straits of Florida: Final Report. NOAA TR ERL 447-AOML-35 (NTIS number not yet available), 50 pp. (1991). The Atlantic Oceanographic and Meteorological Laboratory (AOML) operated a Coastal Ocean Dynamics Applica- tions Radar (CODAR) from 1986 through 1988 in a project to measure ocean surface currents near Miami and produce a series of maps of ocean surface current vectors. The project, CODAR in the Straits of Florida, also evaluated the feasi- bility and value of routine operational use of this HF radar system. The CODAR system produced many excellent maps that showed the west and central portions of the Florida Current. The core speed of this rapid flow, its distance offshore, and the often sharp decrease in speed nearshore were apparent. In addition, the maps showed at times a band of water nearshore that was moving slowly southward along the coast, and sometimes a cyclonic eddy about 15 km in diameter that was centered in a nearly fixed location 20 km northeast of Miami. However, on the whole this CODAR system could not be used as the project planned. The system required excessively frequent maintenance to remain on line. More significantly, the maps produced were inadequate for the intended uses, and too many maps were missing. The maps frequently contained too few current vectors, and without further computer editing, many of the vectors that did appear were grossly incorrect. With added direction editing, major features of the circulation were omitted, and even fewer vectors remained on the maps. Examination of several CODAR maps and the calculated data from which they were pro- duced showed certain limitations of the contractor-supplied data analysis procedure. Various interferences in the antenna voltage readings led to erratic radial velocity readings. In addition, the type of radial velocity combining procedure used was inaccurate with the sometimes erratic data. The concept of a fully automatic system to produce valid CODAR results was not realized in the version of the CODAR system that the project evaluated. In a suggested alternative calculation technique, the assimilation of CODAR data into a numerical model should result in many more maps with few missing data points in the coverage area. This CODAR system might then furnish results equivalent to those from several pre- vious studies that gave valuable information on ocean circulations. AO-054 McPhaden, M.J., D.V. HANSEN, and P.L. Richardson. A comparison of ship drift, drifting buoy, and current meter mooring velocities in the Pacific South Equatorial Current. Journal of Geophysical Research 96(C1 ) :775-781 (1991). In this note we compare mean seasonal cycles of zonal and meridional velocity in the Pacific South Equatorial Current based on current meter mooring data, drifting buoy data, and ship drift data. Monthly averages of ship drift and drifting buoy data were computed over 2° latitude by 10° longitude rectangles centered at the positions of multiyear cur- rent meter moorings near 0°, 110°W, and 0°, 140°W. All three representations of the flow field show the basic charac- ter of the annual mean and its variations, provided that the sampling characteristics associated with each measurement technique are taken into account. In particular, we find that more than 15 days of drifter data (regardless of year) are required on a 2° latitude by 10° longitude basis to produce monthly mean estimates that agree with moored estimates to within about 5-10 cm s"1 rms. We also infer that windage affects climatological monthly mean ship drift velocities, although uncertainties in the data limit a precise determination of the windage magnitude. An upper bound appears to be about 3% of the surface wind speed, though the actual effect of windage may be considerably smaller. AO-055 MOLINARI, R.L., E. JOHNS, and J.F. FESTA. The annual cycle of meridional heat flux in the Atlantic Ocean at 26.5°N. Journal of Physical Oceanography 20(3):476-482 (1990). Total meridional heat flux through a zonal oceanic section at 26.5°N in the Atlantic Ocean is computed from hydro- graphic, direct current, and surface wind observations. The oceanic current and temperature fields are decomposed into depth-averaged and depth-dependent (including Ekman and geostrophic) components to perform the calculation. The mean annual heat flux is estimated to be 1.21 ± 0.34 PW. Mean monthly values of net heat flux are also computed from the data. The annual cycle of net heat flux determined from these values ranges from a minimum of 0.69 PW in February to a maximum of 1.86 PW in July. Thus, in contrast to an earlier estimate of the annual cycle of oceanic heat flux derived indirectly from surface energy fluxes and upper-layer heat content changes, there is no net southward heat flux during the fall. Results from a simulation of the circulation of the North Atlantic give an annual cycle of heat flux similar to our calculations with a summer maximum and winter minimum. However, the simulated mean value and range of the annual cycle are less than observed. 55 AO-056 MOLIN'ARI, R.L., D. Olson, and G. Reverdin. Surface currenl distributions in the tropical Indian Ocean derived from compilations of surface buoy trajectories. Journal of Geophysical Research 95(C5):7217-7238 (1990). Three different satellite-tracked drifting buoy data sets are compiled and used to generate a monthly climatology of surface currents in the tropical Indian Ocean. Buoys were deployed between 1975 and 1987. The data density is maxi- mum on and near the equator and decreases poleward. Drift characteristics of the different buoy configurations are com- pared using a structure function analysis. The differences in windage effects are consistent with the buoy designs and small compared with the signals studied. The currents in the tropical Indian Ocean during boreal winter and spring can be characterized as two counterrotating gyres. A southern clockwise rotating gyre is bounded on the south by the South Equatorial Current (SEC) and on the north during winter by the Equatorial Countercurrent (ECC) and during spring by the Equatorial Jet (EJ). A northern counterclockwise rotating gyre is bounded on the south by the ECC and EJ, depending on season, and on the north by the North Equatorial Current (NEC). The two gyre systems break down during boreal summer. During this season, the SEC is located closer to the equator, and the NEC is replaced by the eastward flowing Indian Monsoon Current (IMC). The western boundary circulation becomes more complicated from late spring through early autumn with the observation of two intense smaller scale gyres. The large-scale southern gyre reappears during boreal autumn with the reappearance of the EJ. The northern gyre begins to reappear in December, with the reversal of the IMC and the reappearance of the NEC. The monthly buoy speeds are compared with a monthly climatology generated from ship drift reports. Differences between the two climatologies are, in general, small except in regions of few trajectories. The annual cycles in amplitudes and phases of the major currents in the region are thus com- parable. AO-057 OOYAMA, K.V. A dynamic test of the diagnostic pressure calculation. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 171 (1991). No abstract. AO-058 OOYAMA, K.V. A thermodynamic foundation for modeling the moist atmosphere. Journal of the Atmospheric Sciences 47(21 ) :2580-2593 (1990). With advances in numerical modeling of the atmosphere, we have experienced that the return to the first principles of physics often enables a model to cope more easily with the complexities of the real atmosphere. The return to the primitive equations of motion from historical balance approximations is an example. This paper proposes a way to return to the "primitive" form of moist thermodynamics, in which prediction is made strictly in terms of conservative properties, such as mass and entropy. There is no conservation law that would apply directly to temperature or pressure. These intensive properties, therefore, should be diagnostically determined by thermodynamics, from the predicted conservative properties. The scope of the paper is limited to the thermodynamics of reversible processes. Irreversible processes, which would make a model alive with real weather, are not discussed here, since each of them requires a separate empir- ical treatment. It is shown, however, that the proposed formulation of thermodynamics facilitates modularization of various approximations within a model, and among models. For example, both the hydrostatic and nonhydrostatic models can be built under an identical design, differing only in the manner of calculating vertical motion. The proposed formulation is extended to include the ice phase within reversible thermodynamics. Also discussed are numerical prob- lems in the spatial representation of thermodynamic discontinuities, which are caused by the phase transition of water substance. AO-059 PALMER, D.R., T.M. Georges, and R.M. Jones. Classical chaos and the sensitivity of the acoustic field to small- scale ocean structure. Computer Physics Communications 65:219-233 (1991). Ray theory is usually the basis of data inversion schemes for acoustic remote sensing of the ocean. Chaotic ray paths are expected to be present whenever the ocean environment possesses small-scale, range-dependent structure. We are studying the implications of their presence for data inversion schemes. Using numerical simulations we consider ray- path characteristics for acoustic remote sensing of the Florida Current. We find small-scale bathymetric structure results in chaotic ray paths and an exponential proliferation of eigenrays. As a result, for each feature in the time-of-arrival pattern, there is associated not a single eigenray but a group, thereby limiting the spatial resolution of a remote sensing system. 56 AO-060 PIOTROWICZ, S.R., C.J. FISCHER, and R.S. Artz. Ozone and carbon monoxide over the North Atlantic during a boreal summer. Global Biogeochemicat Cycles 4(2):215-224 (1990). Ozone mixing ratios observed on a cruise from the east coast of North America to Bermuda, to Iceland, to the Azores and terminating in Barbados in a boreal summer exhibit wide variability. Increases above a North Atlantic back- ground of 10-20 ppbv appear to be associated with transport from terrestrial systems. In the central gyre of the North Atlantic and in the tropical North Atlantic, ozone mixing ratios below 10 ppbv are commonly observed when the air being sampled does not have a recent (10 days) history of terrestrial input. Carbon monoxide mixing ratios within the boundary layer vary latitudinally from an average of 124 ppbv in the westerlies to 88 ppbv in the tropical North Atlantic. Variability in the distribution of CO appears to be dominaled by transport from terrestrial source regions. AO-061 POWELL, M.D. Surface wind distribution of Hurricane Hugo in the Carolinas. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 441-444 (1991). No abstract. AO-062 POWELL, M.D., and P.G. BLACK. Meteorological aspects of Hurricane Hugo's landfall in the Carolinas. Shore and Beach 58(4):3-10 (1990). No abstract. AO-063 POWELL, M.D., and P.G. BLACK. The relationship of hurricane reconnaissance flight-level wind measurements to winds measured by NOAA's oceanic platforms. Journal of Wind Engineering and Industrial Aerodynamics 36:381-392 (1990). A well-known problem in hurricane forecasting and in the administration of hazardous weather warnings and adviso- ries concerns what adjustment to make to flight-level reconnaissance wind observations in order to make them representa- tive of sustained surface winds. To solve this problem, a study was initiated comparing NOAA reconnaissance flight- level winds to 10 m level observations from NOAA's oceanic buoys and platforms. A data base was created that consisted of comparisons made whenever the aircraft observation was: (1) within 10 km radial separation from the sur- face platform (in a storm-relative coordinate system); (2) within ±4 h of the surface observation time; and (3) within +2 h of the surface observation time. The data base contains all storms flown by NOAA aircraft in the vicinity of the Atlantic and Gulf of Mexico buoy network over the 11-year period from 1975-1986. Comparisons from these criteria are discussed in terms of the ratio of the buoy-measured wind speed (Vg) to the aircraft-measured wind speed VA. Results indicate that the 10 m level surface winds over water were within 55%— 85% of the winds measured by the reconnaissance aircraft. The ratio Vg/VA depended strongly on the low-level atmospheric stability as indicated by the buoy air-sea temperature. AO-064 POWELL, M.D., P.P. DODGE, and M.L. BLACK. The landfall of Hurricane Hugo in the Carolinas: Surface wind distribution. Weather and Forecasting 6(3) : 379-399 (1991). Hurricane Hugo struck Charleston, South Carolina, on 22 September 1989 as the most intense hurricane to affect the United States since Camille in 1969. The northeastern eyewall, which contained the maximum winds measured by reconnaissance aircraft shortly before landfall, moved inland over a relatively unpopulated area and there were few fatali- ties. However, no observations were available to document the surface wind distribution in this part of the storm as it continued inland. To improve specification of surface winds in Hugo, empirically adjusted aircraft winds were combined with coastal, offshore, and inland surface observations and were input to the Ooyama objective analysis algorithm. The wind analysis at landfall was then compared with subsequent analyses at 3 and 6 h after landfall. Reconstruction of the surface wind field after landfall suggests that the maximum (-13 min mean) surface wind at the coast was 50 m s"1 in the Bulls Bay region, -40 km northeast of Charleston. Surface roughness over land caused wind speeds to drop off rap- idly just inland of the coast to only 50% of values measured by reconnaissance aircraft at the same location relative to the storm over water. Despite relatively rapid increases in the central sea-level pressure and decreases in the mean circu- lation as Hugo progressed inland, hurricane-force wind gusts extended Hugo's damage pattern well past Charlotte, North Carolina, -330 km inland. Accurate determination of surface wind distribution in landfalling hurricanes is dependent 57 upon the spatial density and quality of surface wind measurements and techniques to adjust reconnaissance flight-level winds to the surface. Improvements should allow forecasters to prepare more accurate warnings and advisories and allow more thorough documentation of poststorm effects. Empirical adjustments to reconnaissance aircraft measurements may replace surface data voids if the vertical profile of the horizontal wind is known. Expanded use of the airborne slepped- frequency microwave radiometer for remote sensing of ocean surface winds could fill data voids without relying upon empirical methods or models. A larger network of offshore, coastal, and inland surface platforms at standard (10 m) elevations with improved sampling strategies is envisioned for better resolution of hurricane wind fields. A rapid-response automatic station network, deployed at prearranged coastal locations by local universities with meteorology and/or wind engineering programs, could further supplement the fixed platform network and avoid the logistical problems posed by sending outside teams into threatened areas. AO-065 PSZENNY, A. A. P., J.N. Galloway, R.S. Artz, and J.F. Boatman. Overview of the 1988 GCE/CASE/WATOX studies of biogeochemical cycles in the North Atlantic region. Global Biogeochemical Cycles 4(2 ): 121-131 (1990). The 1988 Global Change Expedition/Coordinated Air-Sea Experiment/Western Atlantic Ocean Experiment (GCE/ CASE'WATOX) was a multifaceted research program designed to study atmospheric and oceanic processes affecting the biogeochemical cycles of carbon, nitrogen, sulfur, and trace metals in the North Atlantic Ocean region. Field work included: (1) a 49-day research cruise aboard NOAA ship Mt. Mitchell (Global Change Expedition) from Norfolk, Virginia, to Bermuda, Iceland, the Azores, and Barbados; (2) eight flights of the NOAA King Air research aircraft, four off the Virginia Capes and four near Bermuda (CASE/WATOX) ; and (3) a research cruise aboard the yacht Fleurtie near Bermuda (WATOX). Objectives of GCE/CASE/WATOX were: (1) to examine processes controlling the mesoscale distributions of productivity, chlorophyll, and phytoplankton growth rates in Atlantic surface waters; (2) to identify factors controlling the distribution of ozone in the North Atlantic marine boundary layer; and (3) to estimate the contributions of sources on surrounding continents to the biogeochemical cycles of sulfur, nitrogen, and trace metals over the North Atlantic region during the boreal summer season. AO-066 PSZENNY, A. A. P., G.R. HARVEY, C.J. Brown, R.F. Lang, W.C. Keene, J.N. Galloway, and J.T. Merrill. Measurements of dimethyl sulfide oxidation products in the summertime North Atlantic marine boundary layer. Global Biogeochemical Cycles 4(4):367-379 (1990). Chemical data derived from air and precipitation samples collected during the Global Change Expedition/Coordinated Air-Sea Experiment /Western Atlantic Ocean Experiment (GCE/CASE/WATOX) over the North Atlantic Ocean (NAO) are interpreted using simple box models. Estimated total sulfur (S) deposition fluxes from air masses with tropical oceanic, African, clean North American, and polluted North American origins are 4.4, 16, 33, and 70 ^.mol m"2 day"1, respectively, with associated uncertainties of at least factors of 2 to 3. Crude estimates of the fractions of deposition attributable to marine biogenic versus anthropogenic S sources suggest that the latter may be enhancing the natural NAO atmospheric S cycle by a factor of 0.5 to 0.8. Combination with similar estimates for the North Pacific region (Savoie and Prospero, 1989) yields an overall, area-weighted enhancement factor of approximately 0.3 for northern hemisphere ocean areas, consistent with estimates by Wigley (1989) based on climate modeling studies. AO-067 ROSENTHAL, S.L. A note on relationships between Western Sahel rainfall and U.S. hurricane activity. NOAA TM ERL AOML-68 (PB91-17651 1 ) , 22 pp. (1991). A recent research paper concluded that the probabilities of major hurricane strikes on the east coast of the United States, particularly the east coast of Florida, are greatly enhanced when rainfall over the Western Sahel is abundant and that these probabilities are substantially smaller when drought conditions prevail over the Weslern Sahel. This conclusion was based upon a 43-year sample of 1947-1989. In the work presented here, a search is made for simple, statistically significant (at the 5% or better level) relationships between Western Sahel rainfall for 1947-1990 and eight types of hurri- canes that are defined in the text. When hurricane frequencies for the 11 wettest and 11 driest Western Sahel years are compared, statistically significant differences are found for all hurricane types studied, except for Florida landfalling hurricanes. Significant relationships are found for major hurricanes striking the east coast of the United States north of Florida, and for hurricanes of all intensities striking the east coast of the United States north of Florida. However, no significant relationships are found for hurricanes striking Florida. When the wetter 22 years are compared with the drier 22 years, a statistically significant relationship is found for the total of hurricanes of all intensities that strike the Florida Peninsula. For this type of hurricane, the largest frequency is found in the second quartile of Western Sahel rainfall years and not in the wettest quartile. This makes the interpretation of the results difficult. 58 AO-068 Roux, F., and F.D. MARKS, JR. Eyewall evolution in Hurricane Hugo deduced from successive airborne Doppler observations. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 558-563 (1991). No abstract. AO-069 Roux, F. , F.D. MARKS, JR., and J.F. GAMACHE. Three-dimensional circulation in a hurricane from airborne Doppler radar data: Extended velocity track display. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 466-469 (1991). No abstract. AO-070 SHAPIRO, L.J. The effect of vertical wind shear on hurricane motion in a three-layer model. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 356-357 (1991). No abstract. AO-071 Shay, L.K., P.G. BLACK, J.D. Hawkins, R.L. Elsberry, and A.J. Mariano. Sea surface temperature response to Hurricane Gilbert. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 574-578 (1991). No abstract. AO-072 THACKER, W.C. Large least-square problems and the need for automating the generation of adjoint codes: Com- putational solution of nonlinear systems of equations. Lectures in Applied Mathematics 26:645-677 (1990). Some important least-squares problems that arise in oceanography and meteorology are large because they are based on systems of partial-differential equations. The function to be minimized is defined with the aid of a computer code, so the equations stating that the gradient should vanish are not available explicitly. It is possible to construct a second code that evaluates the gradient for a computational effort approximately equal to that of evaluating the function. Since the gradient code can be derived from the fundion code by following a well-defined set of rules, it should be possible to con- struct a compiler-like utility to do this task automatically. Such a compiler should find wide applicability, not only within oceanography and meteorology, but for optimization problems in general, as well as for solving systems of nonlinear equations and for checking the sensitivity of outputs of complicated codes to their inputs. AO-073 TSAI, J.J., and J.R. PRONI. Dredged material disposal at the edge of the Florida Current. First International Ocean Pollution Symposium, Mayaguez, Puerto Rico, April 28-May 3, 1991. University of Puerto Rico, Mayaguez, 80 (1991). A field data collection project was undertaken to evaluate the potential environmental impact of dumping in the designated Miami Ocean Dredged Material Disposal Site before the actual dredging of Miami River and Miami Harbor Turning Basin. Strong Gulf Stream current and relatively deep water depth at the disposal site make the study unique and important. Acoustic remote sensing techniques with current measurements from acoustic Doppler current profiler and in- situ oceanographic measurements were used to monitor the physical processes and the dispersive characteristics. Results indicate that during the period of observations of the study, materials were transported north-northeast away from sensi- tive reef areas and penetrated the strong pycnoclines to reach the bottom in the first few minutes. For the first time, intercomparison among all field data and numerical prediction provides dispersive characteristics of dredged material dis- posal at the western edge of the Florida Current. 59 AO-CT4 WILLIS. P.T.. and J. Halleu. Microphysical measurements from an aircraft ascending with a growing isolaled mar- itime cumulus tower. Journal of the Atmospheric Sciences 48(2) :283-300 (1991). The development of precipitation in the lop of an isolated marine cumulus is traced by four rapid penetrations with an instrumented aircraft between 400 and 1000 m below the visible top of the growing tower. The hydrometeor distribu- tion evolves from the first appearance of a few large supercooled drops [0.45 l"1, D > 0.5 mm] to well-developed precipi- tation (largely ice) in 500 s. This development results from accretion and coalescent growth in the cloud top volume, not from advection by the updraft of large drops from below. Large supercooled drops precede the appearance of ice at -9°C near the cloud top. The cloud and precipitation water budgets are computed and compared with observed values, which indicate that, once precipitation is well-developed, the convective tower cannot maintain itself as a steady-state entity. The budget computations demonstrate a sensitivity of cloud evolution to the ice particle density. AO-075 WILLIS, P.T., and A.J. Heymsfield. Trajectories of hydrometeors in Hurricane Emily. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 192-197 (1991). No abstract. AO-076 WILLIS, P.T., F.D. MARKS, JR., and J. Hallett. Tracing the interactions of precipitation evolution and cloud dynamics using airborne Doppler radar and in-situ data. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 916-919 (1991). No abstract. AO-077 WILLOUGHBY, H.E. Reply. Journal of the Atmospheric Sciences 48(9) : 1209-1212 (1991). No abstract. AO-078 WILLOUGHBY, H.E. Semispectral models of moving hurricane-like vortices. Preprints, 19th Conference on Hurri- canes and Tropical Meteorology, Miami, FL, May 6-10, 1991. American Meteorological Society, Boston, 383-384 (1991). No abstract. AO-079 Winter, A., C. Goenaga, and G.A. MAUL. Carbon and oxygen isotope time series from an 18-year Caribbean reef coral. Journal of Geophysical Research 96(C9): 16,673-16,678 (1991). Colonies of Montastrea annularis live near La Parguera, Puerto Rico, which may be 700 years old. Time series from 1964 to 1982 of 613C and 5lsO from a continuous core of these corals are compared to an adjacent environmental record. At the intra-annual level, 6lsO correlates well with water temperature. Changes in the amplitude of the 6lsO signal between 1967-1976 are attributed to sampling frequency but may be also due to environmental changes such as salinity. Average annual 6lsO, 613C and sea surface temperature show similar trends for the period from 1964-1982 but especially from 1969 onwards. Changes in average annual values during this time interval are most likely due to water mass changes brought about by interannual variability of the North Atlantic circulation. Since water temperatures at La Parguera are representative of changes occurring in the Wider Caribbean, the isotope record from La Parguera corals could be used as a proxy for large scale environmental changes beyond the historical record through the Little Ice Age. 60 Addendum AO-080 Giese, G.S., D.C. Chapman, P.G. BLACK, and J. A. Fornshell. Causation of large-amplitude coastal seiches on the Caribbean coast of Puerto Rico. Journal of Physical Oceanography 20(9) : 1449-1458 (1990). Sea-level oscillations at supertidal frequency with amplitudes of the order of the mean tidal range have been reported from the Caribbean coast of Puerto Rico. Analysis of a 10-year time series of digital tide data from Magueyes Island, Puerto Rico, demonstrates that sea-level variance at the fundamental normal mode (seiche) frequency of the shelf has a pronounced fortnightly distribution with a maximum occurring 6-7 days after new and full moon. The sieche variance also shows a bimodal seasonal distribution with an inverse relationship to easterly wind stress. It is argued that the seiches are excited by internal waves generated by strong tides in the southeastern Caribbean. Support is provided by airborne radar imagery showing sea-surface patterns suggesting the presence of internal waves near the southern Aves Ridge, and by the results of two field experiments, carried out during times when large-amplitude seiches were expected, to research for evidence of internal wave forcing near the shelf break. During the first experiment, large negative-ampli- tude, pulse-like internal waves were recorded 6 km seaward of the shelf break during a period of strong seiche activity. Such pulses were not observed during the second experiment. However, high-frequency temperature variance 2.3 km seaward of the shelf break, possibly resulting from internal surf, increased with depth and reached a maximum 6-7 days following new moon, again suggesting the presence of internal waves. The 10-year time series analysis shows that large tides are necessary, but not sufficient, to generate high seiche activity. This is supported by the two field experiments; during the first, large-amplitude seiches occurred as expected, while during the second experiment they did not. We sug- gest that this behavior is related to variations in stratification, which in turn alter the energy transfer from tides to seiches. AO-081 LONG, R.B., and W.C. THACKER. Data assimilation into a numerical equatorial ocean model, Part 1: The model and the assimilation algorithm. Dynamics of Atmospheres and Oceans 13:379-412 (1989). Numerical modeling provides a powerful tool for the study of the dynamics of oceans and atmospheres. However, the relevance of modeling results can only be established by reference to observations of the system being modeled. Typi- cal oceanic observation sets are sparse, asynoptic, of mixed type and limited reliability, generally inadequate in some respects, and redundant and inconsistent in others. An optimal procedure for interfacing such data sets with a numerical model is the so-called adjoint method. This procedure effectively assimilates the observations into a run of the numerical model by finding that solution to the model equations that best fits all observations made within some specified space- time interval. The method requires the construction of the adjoint of the numerical model, a process made practical for models of realistic complexity by the work of Thacker and Long (1988). In the present paper, the first of 1wo parts, we illustrate the application of Thacker and Long's approach by constructing a data-assimilating version of an equatorial ocean model incorporating the adjoint method. The model is subsequently run for five years to near-steady state, and exhibits many of the features known to be characteristic of equatorial oceanic flows. Using the last 54 days of the run as a control, a set of simulated sea level and subsurface density observations are collected, then successfully assimilated to demonstrate that the procedure can recover the control run, given a generous amount of data. In Part 2, we conduct a sequence of numerical experiments to explore the ability of more limited sets of observations to fix the state of the modeled ocean; in the process, we examine the potential value of sea level data obtained via satellite altimetry. AO-082 LONG, R.B., and W.C. THACKER. Data assimilation into a numerical equatorial ocean model, Part 2: Assimi- lation experiments. Dynamics of Atmospheres and Oceans 13:413-439 (1989). A sequence of numerical experiments is conducted using a linear, semi-spectral equatorial ocean model and an advanced data assimilation scheme. The numerical model is based on decomposition of the oceanic fields into Kelvin and Rossby waves belonging to the baroclinic modes of a stratified equatorial ocean. The assimilation procedure finds that solution to the model equations that best fits, in the generalized least-squares sense, all observations made within some specified space-time interval. All experiments are of the "identical twin" type; synthetic data are generated by sampling the observable fields produced by a control run of the model, then the data are assimilated using the same model. The sequence of numerical experiments serves two purposes: to demonstrate the performance of the assimilation procedure in the context of a fully three-dimensional, time-varying equatorial ocean model, and to examine the utility of specified data sets, and in particular, observations of sea level, in estimating the state of the equatorial ocean. The results indicate that the assimilation procedure works very well when sufficient data are provided. However, sea level data alone are not suf- ficient and must be supplemented with subsurface observations if more than a few baroclinic modes are allowed in the 61 model ocean. The required amounl of supplementary subsurface data (in the form of density profiles in these experi- ments) can be reduced by imposing smoothness contraints on the recovered model solution. AO-083 Molinari. J., and D. Vollaro. Exlernal influences on hurricane intensity. Part II: Vertical structure and response of the hurricane vortex. (Research partially supported by NOAA Grants 50-WCNR-8-06055 and 50-WCNR-9-06080.) Journal of the Atmospheric Sciences 47(15): 1902-1918 (1990). The vertical structure of the interactions of Hurricane Elena (1985) with a baroclinic wave was evaluated using analyses from the European Centre for Medium Range Weather Forecasting. During the period of interaction, azimuthal eddies produced a localized flux convergence of cyclonic angular momentum in the upper troposphere which shifted to progressively small radii prior to major secondary deepening of the storm. These momentum fluxes decayed above and below the outflow layer. Eddy heat fluxes showed maximum cooling in the middle and upper troposphere and warming in the lower stratosphere, reflecting the temperature structure of the baroclinic wave as it moved into the hurricane volume. The response of the hurricane vortex to the fluxes of heat and angular momentum was determined by solution of Eliassen's balanced vortex equation. The balanced solutions showed a band of upward motion, with deep inflow and narrow outflow, which shifted inward from the 500 km radius to the hurricane core in the 24 hours prior to the secondary deepening. The position and timing of this feature corresponded to the contracting outflow maximum found in Part I. Eddy heat fluxes contributed to the induced circulation in the same manner as momentum fluxes near the core, but with smaller magnitude and areal coverage. The contracting outflow maximum thus appeared to represent the upper branch of a secondary circulation excited primarily by the eddy momentum fluxes. The reintensification of hurricanes is often directly associated with formation of a wind maximum at inner radii which replaces or reinforces the original eye wall as it contracts. Such a feature was seen in reconnaissance data in Elena at the time the secondary circulation reached inner radii. It is speculated that the relatively weak secondary circulation evolved into a local wind maximum through the actions of diabatic heat sources. The approaching trough is thus viewed nol as a direct cause of deepening, but as a catalyst which organized the diabatic sources in such a way as to excite internal instabilities of the system. AO-084 ROSENTHAL, S.L. A history of NOAA's Hurricane Research Division, including interactions with F.S.U.'s Department of Meteorology. Proceedings, 40th Anniversary Celebration, Department of Meteorology, Florida State University, November 30-December 1, 1989. Florida State University, Tallahassee, 42-47 (1990). No abstract. AO-085 THACKER, W.C. The role of the Hessian matrix in fitting models to measurements. Journal of Geophysical Research 94:6177-6196 (1989). A numerical model can be fit to data by minimizing a positive quadratic function of the differences between the data and their model counterparts. The rate at which algorithms for computing the best fit to data converge depends on the size of the condition number and the distribution of eigenvalues of the Hessian matrix, which contains second derivatives of this quadratic function. The inverse of the Hessian can be identified as the covariance matrix that establishes the accuracy to which the model state is determined by the data; the reciprocals of the Hessian's eigenvalues representing the variances of linear combinations of variables determined by its eigenvectors. The aspects of the model state that are most difficult to compute are those about which the data provide the least information. A unified formalism is presented in which the model may be treated as either strong or weak constraints, and methods for computing and inverting the Hessian matrix are discussed. Examples of the uncertainties in the best-fit analyses using an oceanographic model are given for several different sets of hypothetical data. 62 CLIMATE MONITORING AND DIAGNOSTICS LABORATORY CM-001 Andreas, E.L., M.W. Miles, R.G. Barry, and R.C. Schnell. Lidar-derived particle concentrations in plumes from Arctic leads. Annals of Glaciology 14:9-12 (1990). With an airborne lidar, we have observed massive plumes of condensate particles rising from wintertime leads in the Arctic Ocean. Some of these plumes reached an altitude of 4 km; some extended over 200 km down-wind from their surface source. Here we invert the lidar equation and use lidar backscatter data to infer particle concentrations within two such plumes. Assuming that the plumes consist of supercooled water droplets of radius 5 (im, we estimate typical concentrations of 3-6 x 10 droplets m just above the leads. Concentrations within the plumes can still be as high as 10 droplets m" at an altitude of 3 km and 200 km down-wind from some leads. Had we assumed that the plume particles are ice spheres of radius 40 (im, concentrations would be just 100 times less than these. CM-002 BATES, J.J. High-frequency variability of special sensor microwave/imager derived wind speed and moisture during an intraseasonal oscillation. Journal of Geophysical Research 96:3411-3423 (1991). Special Sensor Microwave/imager data are used to examine the day-to-day variability of wind speed and precipitable water during the passage of an intraseasonal oscillation. First, SSM/I precipitable water and wind speed algorithms are evaluated for the tropical western Pacific Ocean. The algorithm by Alishouse for retrieving precipitable water vapor retrieves precipitable water value that compare well with island radiosonde observations, but the wind speeds retrieved using the algorithm by Goodberlet et al. compare with buoy wind speeds only marginally. A revised wind speed algorithm, based on regression with buoy wind speeds, is derived for use in this region During the intraseasonal oscillation, anomalously high values of precipitable water, with maximum amplitude at 10°S, accom- pany the movement of convection eastward. Anomalously high wind speed are found to the west of the convection and accompany its movement east. Differences of up to 20% are found along 10°S between the means of daily latent heat flux and U. values and the 60-day mean of these quantities. This implies that high frequency variability must be explicitly accounted for in diagnostics and modeling of air-sea interaction in the western equatorial Pacific Ocean. CM-003 BODHAINE, B.A., N.C. Alquist, and R.C. Schnell. Three-wavelength nephelometer suitable for aircraft measurement of back- ground aerosol scattering coefficient. Atmospheric Environment 25A(10):2267-2276 (1991). A new nephelometer suitable for aircraft measurements of aerosol scattering extinction coefficient (Gsp) has been constructed and operated under field conditions. This instrument is vacuum tight for operation in a pressurized aircraft cabin and is capable of measuring background tropospheric Csp at an averaging time of 1 min. For example, in a typical atmospheric profile the instrument can measure value of about 10 m' with a time resolution of 2s in a polluted region, and about 10* m" with a time resolution of 1 min in a clean region. This sensitivity is made possible by: (1) subtracting in real time the air Rayleigh scattering from the total scattering signal by continuously measuring pressure and temperature in the sampling volume of the instrument; (2) correcting for the dark count and sensitivity of the photomultipliers using a rotating shutter; and (3) using a beam splitter arrangement to allow simultaneous detection by three photomultipliers. A laboratory measurement of instrument noise suggests a 550-nm noise level of about 5 x 10' m" at an averaging time of 1 min. CM-004 BODHAINE, B.A., J.J. DELUISI, J.F. BOATMAN, Y. KIM, D.L. WELLMAN, R.L. GUNTER, M.J. Post, R.E. Cupp, T. McNice, J.M. Rosen, P.J. Sheridan, R.C. Schnell, D.M. Garvey, A.E. Wade, and R.G. Steinhoff. The second front range lidar, aircraft, and balloon experiment. NO A A DR ERL CMDL-8, 142 pp. (1991). The first Front Range Lidar, Aircraft, and Balloon (FRLAB) experiment was performed near Boulder, Colorado, on July 26, 1989, and the second FRLAB experiment was performed on May 23-24, 1990. The purpose of the experiment was to make simultaneous measurements of aerosol profiles in the atmosphere using C02, ruby, Nd:YAG, and ER:Glass lidars; airborne nephelometer, condensa- tion nucleus (CN) counter, and aethalometer; and balloonborne backscattersonde. The data allow a direct comparison between several diverse types of instruments as well as a quantitatively consistent evaluation of the amount of non-Rayleigh scattering occurring in the tropospheric clean region where lidar profiles are often normalized. CM -005 BUTLER, J.H., and J.W. ELKTNS. An automated technique for the measurement of dissolved N20 in natural waters. Marine Chemistry 34:47-61 (1991). We have developed a fully automated technique for measuring dissolved N,0 in freshwater and seawater. This analytical system can measure N20 at intervals as short as 6 minutes in a virtually continuous mode, and it provides for repeat analysis where greater precision is needed. The method, which employs a modified, automated headspace sampler, involves equilibrating a small (15 ml) 63 sample with an inert headspace, subsampling the headspace, and injecting it into an electron capture-gas chromatograph configured for back-flushing. The method is precise to ±2.0% (1 SD) and has been used for more than 3000 measurements of N,0 in the Pacific Ocean, Indian Ocean, and Black Sea. It also has been used to measure N20 dissolved in surface water and groundwater. On a recent cruise to the east Pacific Ocean, we were able to analyze up to 125 samples per day, limited mainly by the frequency of hydrocasts. CM-006 Cess, R.D., E.G. DUTTON, J.J. DELUISI, and F. Jiang. Determining surface solar absorption from broadband satellite measure- ments for clear skies: Comparison with surface measurements. Journal of Climate 4(2):236-247 (1991). Two separate data sets both of which provide measurements of net downward shortwave radiation have been combined, so as to provide a means of critically examining method for transferring satellite measurements to the surface. This is further facilitated through interfacing the two data sets with an atmospheric shortwave-radiation model. One data set comprises near=surface measurements made at the Boulder Atmospheric Observatory Tower while the other consists of collocated satellite pixel measurements from the Earth Radiation Budget Experiment. This study amplifies previous suggestions that surface-shortwave absorption is a more meaningful quantity, for climate studies, than is surface insolation. The former should not, however, be evaluated from the latter through use of a surface albedo, since surface albedo is not solely a surface property nor can it easily be evaluated from satellite measurements. It is further demonstrated that a direct evaluation of surface shortwave absorption can be more accurately obtained from satellite measure- ments than can surface insolation. Specifically, a linear slope-offset relationship exists between surface and surface-atmosphere shortwave absorption, and an algorithm is suggested for transferring satellite shortwave measurements to surface-shortwave absorption. The present study is directed solely at clear-sky conditions because the ciear-sky top-to-surface transfer serves as a necessary prerequi- site towards treating both clear and overcast conditions. CM-007 Cook, E., T. Bird, M. Peterson, M. Barbetti, B. Buckley, R.D'Arrigo, R. Francey, and P. TANS. Climatic change in Tasmania inferred from a 1089-year tree-ring chronology of huon pine. Science 253:1266-1268 (1991). A climatically sensitive huon pine tree-ring chronology from western Tasmania allows inferences about austral summer temperature change since A.D. 900. Since 1965, huon pine growth has been unusually rapid for trees that are in many cases over 700 years old. This growth increase correlates well with recent anomalous warming in Tasmania on the basis of instrumental records and supports claims that a climatic change, perhaps influenced by greenhouse gases, is in progress. Although this temperature increase exceeds any that are inferred to have occurred during the past 1089 years at this location, it has not yet clearly emerged from the natural background variability of climate in this part of the Southern Hemisphere. CM-008 DERR, V.E., R.S. Stone, L.S. FEDOR, and H.P. Hanson. A parameterization for the shortwave transmissivity of stratiform water clouds based on empirical data and radiative transfer theory. Journal of the Atmospheric Sciences 47(23):2774-2783 (1990). Surface measurements of solar flux and total integrated liquid-water content, radiosonde data, and infrared satellite images are analyzed in conjunction with radiative transfer calculations to derive an empirical parameterization for the shortwave transmissivity of continental stratiform water clouds. The data were collected near Denver, Colorado, over a period of six years. Seventeen days on wich uniform stratiform clouds persisted over the observing site were selected for detailed analysis, and form the basis for deriving the parameterization. A multiple reflection radiative transfer model is employed to estimate stratus cloud transmissivity in terms of the measurable liquid-water path (LWP). A nonlinear fit of estimated transmissivities to the corresponding observations of LWP yields close agreement with a previous, more complicated parameterization. The derived expression for cloud transmissivity is used to predict mean daily surface fluxes for 61 days during which periods of stratiform clouds were observed over the Denver area. A comparison between predicted and measured fluxes shows agreement to within ±4%, with best agreement for clouds of moderate optical thickness. Potential sources of error are identified with sensitivity studies. CM -009 Deshler, T. and D.J. HOFMANN. Ozone profiles at McMurdo Station, Antarctica, the austral spring of 1990. Geophysical Research Letters 18(4):657-660 (1991). Vertical profiles of ozone and temperature were measured on 40 occasions during the austral spring of 1990 at McMurdo Station, Antarctica, and once again near record levels of ozone depletion were observed. Total ozone decreased from 260 DU in late August to its minimum value of 145 DU on 9 October, when the ozonesonde was at its lower detection limit from 15 to 16.5 km. Ozone reductions were observed almost exclusively between 12 and 20 km, with a half life of 20 days. This is similar to previous years. Although McMurdo was within the polar vortex for most of the period, there were several occasions when the edge of the vortex was over McMurdo. During these periods, ozone above 20 km approximately doubled, but below 20 km remained relatively unchanged. CM-010 DIAZ, H.F. A comparison of "global" temperature estimates from satellite and instrumental data, 1979-88. Geophysical Research Letters 17(12):2373-2376 (1990). M A comparison of surface temperature changes over land and ocean areas with tropospheric air temperatures derived from satellite measurement over the period 1979-88 reveals differences in the relative rankings of the individual yearly values over the oceans. The discrepancy occurs mainly in the warm half of the set of years, with good agreement evident during the colder half. Since the land data agrees well with the satellite measurements, unless there is an unknown problem with the surface marine temperature, it appears that interannual surface temperature variations over the oceans compare poorly with such variations in the troposphere above it, particularly when the ocean are relatively warm. Agreement between the satellite measurements and an index of tropospheric temperature derived from a set of globally distributed radiosonde stations is excellent. CM-011 DIAZ, H.F. Some characteristics of wet and dry regimes in the contiguous United States: Implications for climate change detection efforts. In Greenhouse-Gas Induced Climatic Change: A Critical Appraisal of Simulations and Observations, M.E. Schlesinger (ed.). Elsevier, Amsterdam, 269-296 (1991). The climatology of wet and dry regimes in five different regions of the contiguous United States is examined using station records of daily precipitation for the period 1931-86. The regions were selected to be representative of different climatological synoptic regimes, and hence are associated with different large-scale atmospheric forcing patterns. The results show that the precipitation - producing processes operating during the wettest and driest years are substantially different, with wet years generally displaying large increases in the heavier precipitation categories compared to the dry years. These differences may be related to changes in the large-scale atmospheric circulation patterns associated with the development of persistent oceanic anomalies associated with variations in air-sea exchange processes over the Pacific Ocean and, depending on the particular region of the country, in the Atlantic Ocean as well. It is shown that sequences of wet and dry years are rather common throughout the country. The 1930s and 50s saw prolonged periods of severe, and in some instances, extreme drought conditions in many parts of the country. There does not appear to be any secular trend in the frequency of either wet or dry regimes through the analysis period. Wet conditions prevailed in much of the country in the early 1980s; a return to drier conditions in the past couple of years, therefore, appears to be just a normal swing to an opposite regime. CM-012 DUTTON, E.G. Annual forcing of the surface radiation balance diurnal cycle measured from a high tower near Boulder, Colorado. Journal of Climate 3(12): 1400- 1408 (1990). The radiation balance consisting of upward and downward components of solar and thermal infrared broadband irradiances is continuously measured from the top of a 300-m tower situated on the Colorado high plains. The data are representative of a weighted areal averaged over a variety of surface and vegetation types within about a 1.5-km radius of the tower. Data from a three-year period, 1986-88, appears to be sufficient to define smooth annual cycles in monthly averages and 1-h resolution diurnal cycles in seasonal averages. It is found that even though infrared cycles are out of phase with cycles of corresponding solar components, the overall net radiation balance is in phase with surface solar forcing. The latter follows closely the extraterrestrial forcing but with some phase modifications by clouds and surface reflectance variations. The value of the correlation coefficient squared between the extraterrestrial radiation and the measured surface radiation balance quickly increases from 0.89-0.99 as averaging time increases from 1-90 days, respectively. CM-013 DUTTON, E.G., and D.J. ENDRES. Date of snowmelt at Barrow, Alaska, U.S.A. Arctic and Alpine Research 23(1):1 15-119 (1991). The date of snowmelt near Barrow, Alaska, for recent years is determined from radiometric in situ measurements of the tundra solar albedo. The snowmelt dates determined from the albedo measurements dispute recently published values based on routine visual observations at the Barrow National Weather Service (NWS) Office. Local heat-budget-altering effects of the village and its recent abrupt growth are suggested as the cause for the disagreement between the rural albedo and NWS "in town" observations. The open tundra albedo measurements combined with historical NWS observations suggest that there is no significant trend in the date of snowmelt near Barrow. CM-014 DUTTON, E.G., R.S. Stone, D.W. NELSON, and B.G. MENDONCA. Recent interannual variations in solar radiation, cloudiness, and surface temperature at the South Pole. Journal of Climate 4:848-858 (1991). Incoming global solar irradiance measured at the surface at the South Pole unexpectedly decreased steadily by 15% from 1976 through 1987 during the late austral summer season whereas no trend is apparent for September through December. February's irradiance trend, -1.25% yr on the average, is statistically significant at greater than the 99.9% confidence level. The irradiance observations were made continuously with the same calibrated sensor and are confirmed by a second simultaneous solar irradiance measurement series. Associated changes in seasonal sky cover (clouds) and surface air temperature were also observed. Seasonally increasing cloud cover is directly associated with the decreasing irradiance trends whereas temperatures show a warming significant only in March followed by a cooling trend, significant only in May. Thirty-two-year cloudiness and temperature records suggest that the 65 observed cloudiness trend began in the late 1970s while the temperature trends become apparent only in the early 1980s. The observed sensitivity of total global solar irradiance to the change in sky cover is roughly 6.0% per one-tenth and is shown to vary spectrally. Although the annual averages of solar in-adiance at the South Pole display an overall decrease between 1976 and 1989, the most recent years in this period show some recovery from earlier declines. Likewise, the downward trend in January and February irradiance diminished in 1988 and 1989. CM-015 Eischeid, J.K., H.F. DIAZ, R.S. Bradley, and P.D. Jones. A Comprehensive Precipitation Data Set for Global Land Areas. DOE/ER-69017T-H1, U.S. Department of Energy, Washington, DC, 82 pp (1991). An expanded and updated compilation of long-term station precipitation data, together with a new set of gridded monthly mean fields for global land areas are described. The present data set contains 5328 station records of monthly total precipitation, covering the period from the mid-1980s to the late 1980s. The station data were individually tested and visually inspected for the presence of spurious trends, jumps, and other measurement biases. The quality control procedure which was used to check the station records for non-climatic discontinuities and other biases is detailed. We also discuss some of the problems which typically contribute to potential inhomogeneities in precipitation records. The station data were interpolated onto a 4° latitude by 5" longitude uniform grid. Compari- sons of these data with two other global-scale precipitation climatologies are presented. We find good agreement among the three global-scale climatologies over the common areas in each set. Three different indices of long-term precipitation variations over the global land areas all indicate a general increase of annual precipitation since the 1940s, although a decline is evident over the last decade. There is some indication that the last few decades of the 19th century may have been as wet as the recent ones. An interesting feature of this study is the presence of relatively large differences in seasonal trends, with March-May and September-November becoming wetter in the last few decades. The December-February and June-August seasons exhibit smaller overall trends, although the northern winter season does exhibit large decadal-scale fluctuations. CM-016 Fiocco, G., D. Fua, M. Cacciani, P. DiGirolamo, and J. DELUISI. On the temperature dependence of polar stratospheric clouds. Geophysical Research Letters 18(3):424-427 (1991). Polar stratospheric clouds were frequently observed by lidar at the Amundsen-Scott South Pole Station during May-October 1988. The dependence of the backscattering cross section on the temperature can be referred to transitions of the HN03/H20 system: it appears possible to distinguish the pure trihydrate from the mixed ice-trihydrate phase in the composition of the aerosol and, in some cases, to bracket the HN03 and H20 content of the ambient gas, and to provide indications on the size of the particles. CM-017 Grossman, R.L., and O. Garcia. The distribution of deep convection over ocean and land during the Asian summer monsoon. Journal of Climate 3(9): 1032- 1044 (1990). The highly reflective cloud (HRC) data set is a daily index of organized deep convection, at one degree resolution, from 17 years of polar-orbiting satellite imagery. These data are used to analyze and discuss the climatological geographical distribution of deep convection observed over the Asian summer monsoon season and its component months (June, July, August, and September). Intraseasonal variations of convection for selected regions are examined using normalized pentad time series of regional median HRC values. We also compare HRC data over two regions (western coastal India and western coastal Burma/Thailand) with the results from a two-dimensional numerical model, consisting of a simple differentially heated land-ocean system which predicts that a preponderance of deep convection occurs over the coastal zone. The Burma/Thailand regional comparison supports the model result. Comparison of the model with the western coastal India region is less conclusive, which my be due to the limitations of the model. We conclude that monsoon deep convection, and its attendant sources of latent heat, momentum, and mass sources important to large-scale monsoon dynamics is localized and persistent from year to year. If, as hypothesized by others, tropical cumulonimbus activity is important to stratospheric-tropospheric exchange, this study shows the preferred areas of such exchange during the monsoon. The locations of areas with large HRC amounts are consistent with upstream lifting of low-level, conditionally unstable air by low, coastal mountains. Intraseasonal variability follows variations in sea surface temperature and low-level flow. Upper-level dynamics are also recognized as an important contribution. CM-018 Hendon, H.H., and B. Liebmann. A composite study of onset of the Australian summer monsoon. Journal of the Atmospheric Sciences 47(18): 2227-2240 (1990). Onset of the Australian summer monsoon is identified each year (1957-87) using the wind and rainfall record of Darwin. Onset is defined at the first occurrence of wet, 850 mb westerly winds. Composites of atmospheric fields at stations in and about the Australian tropics are constructed relative to the onset date at Darwin. The composite onset is accompanied by the development of a convectively driven, baroclinic circulation over northern Australia. Upper tropospheric easterlies expand about the equator and the subtropical jet shifts poleward at onset. This behavior is interpreted as a transient southerly shift of the local Hadley circulation concurrent with the development of an upper level anticyclone over northern Australia. The composite onset coincides with the arrival of an eastward propagating convective anomaly. The anomaly originates in the southern Indian Ocean, propagates eastward at 5 m s" and is detectable 66 as far east as the data line. An eastward propagating zonal wind anomaly also is detectable at tropical stations east and west of Darwin. These features are indicative of the 40-50 day oscillation and thus the composite onset is concluded to coincide with the traversal of the oscillation across northern Australia. The composite onset is further shown to coincide with the first occurrence of the convectively active 40-50 day oscillation during each southern summer. CM -01 9 Hendon, H.H., and B. Liebmann. The intraseasonal (30-50 day) oscillation of the Australian summer monsoon. Journal of the Atmospheric Sciences 47(24):2909-2923 (1990). The tropical intraseasonal (30-50 day) oscillation manifests itself in the Australian summer monsoon by a pronounced modulation of the monsoonal westerlies. These 30-50 day fluctuations of the monsoonal westerlies are coherent with rainfall and OLR across northern Australia. The OLR fluctuation originates in the Indian Ocean and systematically propagates eastward at 5 m s , consistent with previous studies of the intraseasonal oscillation. The detailed evolution of the intraseasonal oscillation of the monsoon is studied via composites of upper air data in and about the Australian tropics. During the summer periods 1957-87, 91 events were identified at Darwin, Australia. The composite oscillation at Darwin has a very deep baroclinic structure with westerlies extending up to 300 mb. The westerly phase lasts about 10 days and lags a similar duration rainfall event by about 4 days. During the westerly phase, the upper troposphere is warm and the extreme lower troposphere is cool. This structure is consistent with midtropospheric latent heating and lower tropospheric cooling due to evaporation of falling rain. The magnitude of the composite oscillation at Darwin is about 5 m s"1 in zonal wind, 1ms" in meridional wind, 0.5°K in temperature, 5 mm rainfall per day, and 10% in relative humidity. The oscillation at Darwin is readily traced as far west as Cocos Island and as far east as Pago Pago. Above northern Australia, enhanced synoptic scale variability develops during the wet-westerly phase of the oscillation. Analysis of a single station record precludes documentation of the structure of these synoptic fluctuations. In the Northern Hemisphere midlatitudes, a wave train in 500 mb heights appears to emanate from the longitude of the Australian tropics during the wet-westerly phase. The magnitude of this wave train is only about 50 m while the wave train undergoes a systematic evolution a the tropical convective anomaly moves west to east, no sense of dispersion from a localized low-latitude heat source is evident. CM-020 Hoerling, M.P., G.N. Kiladis, and K. WEIKMANN. A diagnostic study on the origin of persistent Northern Hemisphere climate anomalies during January-February 1990. Proceedings, 15th Annual Climate Diagnostics Workshop, Asheville, North Carolina, October 29-November 2, 1990. National Weather Service, Climate Analysis Center, Washington, DC, 11-17 (1991). Extended abstract. CM-021 HOFMANN, D.J., S.J. OLTMANS, and T. Deshler. Simultaneous balloonborne measurements of stratospheric water vapor and ozone in the polar regions. Geophysical Research Letters 1 8(6):101 1-1014 (1991). Vertical profiles of stratospheric water vapor and ozone were measured together at McMurdo and South Pole Stations in Antarctica and at Kiruna, Sweden, on several occasions during during the austral spring of 1990 and the boreal winter of 1991. The Antarctic data indicated that major dehydration had occurred on a continental scale over the winter stratospheric cloud formation period leaving only 2 to 3 ppmv water vapor between 1 1 and 19 km. Measurements before and after movement of the boundary of the polar vortex across McMurdo detected increases in both water vapor and ozone in the 17 to 20 km region. This injected layer was still observed at South Pole Station a month later suggesting continental proportions. In early November, with the vortex still intact. South Pole measurements indicated a substantial degree of inhomogeneity in both water vapor and ozone in the lower stratosphere. In comparison, stratospheric water vapor measurements in the Arctic gave values of 4 to 5 ppmv indicating the absence of the gross stratospheric dehydration effects obvious in the Antarctic, and they did not reveal significant structure except on one occasion with very cold temperatures (-90°C) at 25 km and nacreous cloud displays. CM-022 Joseph, P.V. Possible oceanic control of the speed of northward advance of summer monsoon rains over Peninsular India. TOGA Notes, Nova University Press, Bania, Florida, 1:8-10 (1990). No abstract. CM-023 Joseph, P. V., J.K. Eischeid, and R.J. Pyle. SST anomalies and the temporal evolution of OLR and 850 mb wind fields in relation to the onset of the summer monsoon rains over South Asia. Proceedings, 15th Annual Climate Diagnostics Workshop, Asheville, North Carolina, October 29-November 2, 1990. National Weather Service, Climate Analysis Center, Washington, DC, 281-285 (1991). Extended abstract. 67 CM-024 Joseph, P. V., and B. Liebmann. Association between the Indian summer monsoon and tropical cyclones of the western North Pacific. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, Florida, May 6-10, 1991, American Meteorology Society, Boston, 369-371, (1991). No abstract. CM -025 Joseph, P. V., B. Liebmann, and H.H. Hendon. Interannual variability of the Australian summer monsoon onset: Possible influence of Indian summer monsoon and El Nino. Journal of Climate, 4(5): 529-538 (1991). The date of the Australian summer monsoon onset (ASMO) is found to be well correlated with the monsoon rainfall of India during the preceding June to September. Years of below (above) normal Indian summer monsoon rainfall (ISMR) are followed by delayed (early) ASMO. Sea surface temperature (SST) anomalies during the September to November season over the tropical Indian Ocean, the equatorial eastern Pacific Ocean, and the ocean north of Australia also correlate significantly with the date of the following ASMO. Delays in ASMO are associated with cold SST north of Australia and warm SST in the tropical Indian and equatorial east Pacific oceans. Previous studies have shown that a warm SST is created over the tropical Indian Ocean in years of poor ISMR. We hypothesize that a warm SST anomaly over the Indian Ocean delays the seasonal southward and eastward migration of the cloudiness maximum. A delay in the southeastward movement of cloudiness results in a delayed ASMO. A similar hypothesis already has been suggested to explain the variability of the date of monsoon onset over India. Weak ISMR often is associated with the contemporaneous presence of El Nino, although many weak monsoons occur without El Nino. Thus warm SSTs in the eastern equatorial Pacific are related to a delayed ASMO through the Indian monsoon. Another signature of El Nino is the presence of negative SST anomalies north of Australia, adding to the delay in ASMO. Warm SSTs in the central and eastern Pacific may also act directly to delay ASMO by causing convection near an east of the date line and subsidence near Australia. CM-026 Kahl, J.D. Characteristics of the low-level temperature inversion along the Alaskan Arctic coast. International Journal of Climatology 10:537-548 (1990). The climatological characteristics of low-level tropospheric temperature inversion along the Alaskan Arctic coast are examined from a 10-year record of surface and upper-air meteorological data at Barrow and Barter Island, Alaska. The meteorology at the two stations is found to be remarkably similar; surface-based inversions occur nearly half of the time, but even in the winter months inversions are frequently based up to 200 m above the surface. Median inversion depths range from 250 m to 850 m, with median temperature differences across the inversion ranging from 2"C to 11°C. In March and April when the inversion is strongest, the lowest levels frequently erode. This indicates that the transient character of the inversion reduces its effectiveness as a barrier to vertical mixing. The inversion depth closely follows the annual cloud-cover cycle, demonstrating that the development and maintenance of the inversion is a result of complex interactions between radiative forcing, synoptic activity, and sea-ice dynamics. CM-027 Kahl, J.D., R.C. Schnell, P.J. Sheridan, B.D. Zak, H.W. Church, A.S. Mason, J.L. Heffter, and J.M. HARRIS. Predicting atmos- pheric debris transport in real-time using a trajectory forecast model. Atmospheric Environemnt 25A(8):1705-1713 (1991). An experiment is described in which a trajectory forecast model was used in real-time to estimate the transport of debris associated with a large chemical explosion in the southwestern U.S. The forecast trajectories were used to vector sampling aircraft into a position favorable for intersecting the debris cloud. The forecasts are evaluated and compared with three independent measure of debris transport: diagnostic trajectories calculated after the experiment using observed wind fields; transport of a tracer balloon; and aircraft measurements of the debris cloud. Trajectory forecasts originating as early as 39 h before the explosion successfully predicted the downwind atmospheric drift pathway of the cloud. The forecast trajectories agreed well with diagnostic trajectories, confirming the high quality of the meteorological forecast data upon which the trajectories are based. The forecast trajectories also proved skillful in predicting real-time atmospheric motion at short notice. The results support our conclusion that forecast trajectory models are valuable tools for vectoring sampling aircraft in long-range atmospheric dispersion experiments and operations. These models should prove useful in the future when real-time estimates of atmospheric transport are needed. CM-028 Kiladis, G.N., and K. WEICKMANN. Intraseasonal relationships between circulation anomalies and tropical convection during northern winter. Proceedings, 15th Annual Climate Diagnostics Workshop, Asheville, North Carolina, October 29-November 2, 1990. National Weather Service, Climate Analysis Center, Washington, DC, 137-142 (1991). No abstract. 68 CM-029 KOMHYR, W.D., J. WENDELL, and J.A. LATHROP. ECC ozonesonde observations at Pt. Barrow, Alaska, during January 16-April 19, 1989. NOAA DR ERL-CMDL-7, 155 pp. (1991). Atmospheric ozone vertical distributions and air temperatures are presented for 33 balloon electrochemical concentration cell (ECC) ozonesonde soundings made at Point Barrow, Alaska (71* 18'N, 156° 47'W, 4 m), during January 16-April 19, 1989. CM-030 KOMHYR, W.D., S.J. OLTMANS, R.D. GRASS, and R.K. Leonard. Possible influence of long-term sea surface temperature anomalies in the tropical Pacific on global ozone, Canadian Journal of Physics, 69:1093-1102 (1991). A significant negative correlation exists between June-August sea surface temperatures (SSTs) in the eastern equatorial Pacific and 15-31 October total ozone values at South Pole, Antarctica. SSTs in the eastern equatorial Pacific were anomlously warmer by 0.67°C during 1976-1987 compared with 1962-1975. Quasi-biennial oscillation (QBO) easterly winds in the equatorial Pacific stratosphere were generally stronger after 1975 than they were before that time. Prior to the early-to-mid 1970s the trend in global ozone was generally upward, but then turned downward. Total ozone at Hawaii and Samoa, which had been decreasing at a rate of about 0.35% yr"1 during 1976-1987, showed recovery to mid-1970s values in 1988-1989 following a drop in SSTs in the eastern equatorial Pacific to low values last observed there prior to 1976. During 15-31 October 1988, total ozone at South Pole, which had decreased from about 280 Dobson units (DU) prior to 1980 to 140 DU in 1987, suddenly recovered to 250 DU, though substantial ozone depletion by heterogenous photochemical processes involving polar stratospheric clouds was still evident in the South Pole ozone vertical profiles. These observations suggest that the downward trend in ozone observed over the globe in recent years may have been at least partially meteorologically induced, possibly through modulation by the warmer tropical Pacific Ocean waters of QBO easterly winds at the equator, of planetary waves in the extratropics, of the interaction of QBO winds and planetary waves, and of Hadley cell circulation. A cursory analysis of geostrophic wind flow around the Baffin Island low suggests a meteorological influence on the observed downward trend in ozone over North America during the past decade. Because ozone has a lifetime that varies from minutes to hours in the primary ozone production region at high altitudes in the tropical stratosphere to months and years in the low stratosphere, changes in atmospheric dynamics have the potential for not only redistributing ozone over the globe, but also changing global ozone abundance. CM -031 KOMHYR, W.D., R.D. Evans, R.D. GRASS, G.L. KOENIG, J.A. LATHROP, and D.M. Quincy. Dobson spectrophotometer, ECC ozonesonde, and ground-based NOAA SBUV-2, S/N-2 satellite instrument comparison ozone observations. NOAA DR ERL CMDL-6, 17 pp. (1990). Dobson spectrophotometer total ozone and Umkehr and ECC ozonesonde ozone vertical distribution observations were made in Boulder, Colorado, in early April 1990 when similar observations were made quasi-simultaneously with a ground-based NOAA SBUV-2, SN-2, satellite ozone instrument at the Ball Corporation research and manufacturing facility in Boulder. Data obtained will be used by a team of experts from Ball Corporation and NASA in assessing their laboratory calibrations of the SBUV-2 instrument. CM-032 Kopcewicz, B., C. NAGAMOTO, F. PARUNGO, J. HARRIS, J. MILLER, H. Sievering, and J. Rosinski. Morphological studies of sulfate and nitrate particles on the east coast of North America and over the North Atlantic Ocean. Atmospheric Research 26:245-271 (1991). Shipborne and airborne aerosol samples were collected during the Coordinated-Air-Sea Experiment (CASE) over the western north Atlantic Ocean. The experiment was accompanied by measurements on shore near Hampton, Virginia. Individual particle morphology, size, n concentration were analyzed with an electron microscope. Particles containing sulfuric acid, sulfate, nitric acid, and nitrate were identified with various morphological tests. Temporal and spatial variations of aerosol physico-chemical characteristics were studied in relation to atmospheric parameters. A diurnal solar radiation effect on concentration and chemical composition of small sulfate- containing particles (0.2 Jim = Q .. 6(t-t'). The POP method is applied to data from a direct 71 simulation Monte Carlo program. The system is a dilute gas with 50,000 particles in a Rayleigh-Benard configuration. The POP analysis correctly reproduces the linearized Navier-Stokes equations (in the matrix B) and the stochastic fluxes (in the matrix Q) as given by Landau-Lifschitz fluctuating hydrodynamics. Using this method, we find the Landau-Lifschitz theory to be valid both in equilibrium and near the critical point of Rayleigh-Benard convection. CM-042 Penland, C, and M. Ghil. Principal oscillation patterns used in forecasting. Proceedings, 15th Annual Climate Diagnostics Workshop, Asheville, North Carolina, October 29-November 2, 1990. National Weather Service, Climate Analysis Center, Washington, DC, 355-359 (1991). Extended abstract. CM-043 Reddy, P.J., F.W. Kreiner, J.J. DELUISI, and Y. Kim. Aerosol optical depths over the Atlantic derived from shipboard sun- photometer observations during the 1988 global change expedition. Global Biogeochemical Cycles 4:225-240 (1990). Aerosol optical depths and values for the Angstrom exponent, alpha, were retrieved from carefully calibrated sunphotometer measurements which were made during the Global Change Expedition (GCE) of the NOAA ship Ml. Mitchell in July, August, and September 1988. Sunphotometer observations were acquired at wavelengths of 380, 500, 675, and 778 nm. Optical depths and alphas have been segregated into five categories associated with probable air mass source regions determined through back trajectories at the 1000-, 850-, 700-, and 500-mbar levels. The results for the three most distinct air mass types are summarized here. The mean 500-nm aerosol optical depth for North American air is 0.56 (±0.32), the mean for Atlantic air is 0.16 (±0.2), and the mean for Saharan air is 0.39 (±0.12). Alpha for mean GCE aerosol optical depth data for predominantly North American air masses is 1.15 (±0.11), alpha for Atlantic air is 1.00 (±0.40), and for Saharan air, alpha is 0.37 (±0.18). There is a significant difference between alpha for Saharan air and alpha for North American or Atlantic air. There is also a significant difference between the mean 500-nm optical depth for North American aerosols and Atlantic aerosols. CM-044 RYAN, S. Diurnal C02 exchange and photosynthesis of the Samoa tropical forest. Global Biogeochemical Cycles 4(l):69-84 (1990). The exchange of CO, between the atmosphere and tropical forest ecosystem of American Samoa was continuously monitored for 3 days in December 1988. The island was modeled as a simple wind-ventilated respiration chamber with C02 input concentration, C02 output concentration, and residence time as measured variables. Net ecosystem production rates were calculated by incorporating Gaussian vertical diffusion into the model. Nighttime respiration averaged 0.34 (±0.06) g C m h ; peak midday uptake was 0.85 (±0.23) g C m h'1. Thirty -nine percent (±30%) more carbon was assimilated by the ecosystem during the day than was released at night. The diurnal net ecosystem production averaged 1.5 g C m d" . The daytime C02 exchange rate varied as the logarithm of incident solar radiation over a range of 30 W/m2 to 900 W/m , with r = 0.87. Total ecosystem respiration equaled photosynthesis at a radiation intensity of 72 (±14) W/M . The saturation intensity was 600 W/m2. CM-045 Schnell, R.C., S.C. Liu, S.J. OLTMANS, R.S. Stone, D.J. HOFMANN, E.G. DUTTON, T. Deshler, W.T. Sturges, J.W. Harder, S.D. Sewell, M. Trainer, and J.M. HARRIS. Decrease of summer tropospheric ozone concentrations in Antarctica. Nature 351:726-729(1991). As an oxidant and a precursor for other highy reactive oxidants, ozone plays an important role in tropospheric photochemistry. Li the upper troposphere, ozone absorbs infrared radiation and is thus an effective greenhouse gas. Here we show that surface ozone concentrations at the South Pole in the austral summer decreased by 17% over the period 1976-90. Over the same period, solar irradiance at the South Pole in January and February decreased by 7% as a result of a 25% increase in cloudiness. We suggest that the trend in the summer ozone concentrations is caused by enhanced photochemical destruction of ozone in the lower troposphere caused by the increased penetration of ultraviolet radiation associated with stratospheric ozone depletion, coupled with enhanced transport of ozone-poor marine air from lower latitudes to the South Pole. CM -046 Stone, R.S., and J.D. Kahl. Variations in boundary layer properties associated with clouds and transient weather disturbances at the South Pole during winter. Journal of Geophysical Research 96(D3):5 137-5 144 (1991). Both the increasing concentrations of greenhouse gases and potential changes in cloud distributions are likely to affect the surface energy budget of the polar regions. Changes in the polar atmosphere are linked to dynamical processes that control the transport of mass, heat, and moisture from lower latitudes and in turn, feed back into the global circulation. Radiation and meteorological data collected at the South Pole during the 1986 austral winter are analyzed to gain a better understanding of the relationships between cloud 72 radiative effects, transport processes and the vertical distribution of temperature and wind. An algorithm is developed to characterize the quasi-permanent surface-based temperature inversion and the "warm" radiatively active layer above it. Mean winter temperature and wind profiles for clear and overcast conditions are combined with surface radiation measurements and synoptic circulation patterns to study the mechanisms that cause periodic weakening of the inversion. Results support previous studies that ascribe this weakening to (1) warm air advection, (2) downward vertical muting of sensible an latent heat, and (3) longewave cloud radiative heating. The integrity of the inversion depends on the combined effects of all three mechanisms. Parameters representing the intensity of the inversion and the bulk wind shear through the lower troposphere are suggested as appropriate indices of the detection of climate change in the region of the Antarctic Plateau. CM-047 STUNDER, B.J.B., R.S. ARTZ, CD. ROLPH, J.M. HARRIS, and J.T. Merrill. Summary of meteorological conditions over the North Atlantic Ocean during GCE/CASE/WATOX. Global Geochemical Cycles 4(2):133-150 (1990). During the summer of 1988, a team of scientists aboard the NOAA ship Ml. Mitchell and the NOAA King Air aircraft investigated the spatial distributions of sulfur, nitrogen, and related species and their interactions over the North Atlantic Ocean. In support of these measurements, meteorological data from the National Meteorological Center and from rawinsonde data obtained from the ship were archived and back trajectories were calculated. A summary of the meteorological conditions during the cruise is presented using synoptic maps, soundings, cross sections, and isobaric and isentropic back trajectories. Since day-to-day variability of the synoptic situation was generally small, one representative day was chosen to illustrate the overall meteorology. During the cruise, three synoptic regimes were encountered: (1) north of the polar front, (2) under the Bermuda/Azores high, and (3) under the Intertropical Convergence Zone (ITCZ). Soundings from three different days illustrate these regimes. Boundary layer depth and cloud layers were also estimated from all the soundings. Cross sections of temperature, wind, and relative humidity describing the vertical structure of the atmosphere along the cruise show the general day-to-day uniformity except near the polar front and near the ITCZ boundary. The back trajectories show general air flow patterns and the land mass source regions of air reaching the ship within three days. For parts of the cruise, air reached the ship from North America, Iceland or Greenland, Africa, and South America. CM-048 Sturges, W.T., and B.E. Taylor. Atmospheric concentrations of chlorinated solvents around a nuclear processing plant in Colorado. Environmental Technology 1 1:1063-1070 (1990). Atmospheric concentrations of chlorinated solvents were determined in the vicinity of a major user of such compounds in Colorado. Samples were collected using Tenax absorbent and analyzed by thermal desorption-GC/ECD. Comparison of samples collected upwind an downwind of the plant revealed that on certain days there were significant releases of methyl chloroform and, to a lesser extent, carbon tetrachloride from the plant. There was no evidence for consistent releases of other chlorinated solvents. CM -049 Ting, M. An idealized GCM response to mid-latitude SST anomalies. Proceedings, 15th Annual Climate Diagnostics Workshop, Asheville, North Carolina, October 29-November 2, 1990. National Weather Service, Climate Analysis Center, Washington, DC, 337-343 (1991). Extended abstract. CM-C50 Ting, M. The stationary wave response to a midlatitude SST anomaly in an idealized GCM. Journal of Atmospheric Science 48:1249-1275. The atmospheric stationary wave response to a midlatitude sea surface temperature (SST) anomaly is examined with an idealized general circulation model (GCM) as well as steady linear model, in a similar way as Ting and Held, for a tropical SST anomaly. The control climate of the GCM is zonally symmetric; this symmetric climate is then perturbed by a monopole SST anomaly centered at 40°N. Two experiments, with SST anomalies of opposite sign, have been conducted. The stationary response is roughly linear in the sign of the SST anomaly, despite the fact that precipitation shows strong nonlinearity. The linear model, which is an exact linearization of the GCM equations in use, when forced by anomalous heating and transients, reproduces the GCM's stationary response excellently. The low-level transient eddy heat fluxes act to damp the lower level temperature signal. When this damping effect is mimicked by a horizontal thermal diffusion in the linear model, the response to the diabatic heating alone gives a reasonably good simulation of the GCM's anomaly; the effect of the anomalous transient momentum fluxes is relatively small. A crude latent heat parameterization scheme, using an evaporation anomaly that is proportional to the mean air-sea surface moisture difference and including the effects of mean moisture advection, is developed. When the perturbation mixing ratio is approximated by assuming fixed relative humidity and by linearizing the Clausius-Clapeyron equation, the linear model's response, utilizing this latent heat parameterization scheme, gives a useful fit to the GCM's anomalous flow. 73 CM-051 WEICKMANN, K. El Niiio/Southem Oscillation and Madden-Julian (30-60 day) oscillations during 1981-1982. Journal of Geophysical Research 96:3187-3195 (1991). An important issue in understanding the low-frequency oscillations of the atmosphere and the ocean-atmosphere system concerns the role of transients during individual events. This question is examined from an observational point of view for the period from September 1981 to April 1982, which includes the transitional phase of the 1982-1983 El Nino/Southern Oscillation (ENSO) cycle, as well as six Madden-Julian (30-60 day) oscillations (MJO). For the developing ENSO, it is shown that interannual transitions in the anomalous atmospheric circulation and in the sea surface temperatures in the western-central Pacific coincide with the passage of strong MJOs from the Indian to Pacific oceans. For a MJO during December 1981, evidence is provided that the shift of convection from the eastern Indian Ocean to the western Pacific Ocean involves transients having periods around 10 days. The role of transients is discussed from the perspective of these interannul and intraseasonal modes. CM-052 Wolter, K., and M.-Y. Liu. ENSO in Pacific COADS; 1854-1988. Proceedings, 15th Annual Climate Diagnostics Workshop, Asheville, North Carolina, October 29-November 2, 1990. National Weather Service, Climate Analysis Center, Washington, DC, 36-41 (1991). Extended abstract. 74 FORECAST SYSTEMS LABORATORY FS-001 ALBERS, S.C. The detection of isolated tomadic vortext signatures with NEXRAD algorithms. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 123-126 (1991). No abstract. FS-002 BENJAMIN, S.G. Short-range forecasts from a 3-h isentropic-sigma assimilation system using ACARS data. Preprints, Fourth International Conference on Aviation Weather Systems, Paris, France, June 24-26, 1991. American Meteorological Society, Boston, 329-334(1991). No abstract. FS-003 BENJAMIN, S.G., K.A. Brewster, R. Brummer, B.F. Jewett, T.W. SCHLATTER, T.L. SMITH, and P.A. STAMUS. An lsentropic three-hourly data assimilation system using ACARS aircraft observations. Monthly Weather Review 1 19(4):888-906 (1991). A 3-h intermittent data assimilation system (Mesoscale Analysis and Prediction System-MAPS) configured in isentropic coordinates was developed and implemented in real-time operation. The major components of the system are data ingest, objective quality control of the observations, objective analysis, and a primitive equation forecast model, all using isentropic coordinates to take advantage of the improved resolution near frontal zones and greater spatial coherence of data that this coordinate system provides. Each 3-h forecast becomes the background for the subsequent analysis; in this manner, a four-dimensional set of observations can be assimilated. The primary asynoptic data source used in current real-time operation of this system is aircraft data, most of it automated. Data from wind profilers, surface observations, and radiosondes are also included in MAPS. Statistics were collected over the last half of 1989 and into 1990 to study the performance of MAPS and compare it with that of the Regional Analysis and Forecast System (RAFS), which is run operationally at the National Meteorological Center (NMC). Analyses generally fit mandatory-level observations more closely in MAPS than in RAFS. Three- hour forecasts from MAPS, incorporating asynoptic aircraft reports, improve on 12-h MAPS forecasts valid at the same time for all levels and variables, and also improve on 12-h RAFS forecasts of upper-level winds. This result is due to the quality and volume of the aircraft data as well as the effectiveness of the isentropic data assimilation used. Forecast fields at other levels are slightly poorer than those from RAFS. This may be largely due to the lack of diabatic and boundary-layer physics for the MAPS model used in this lest period. FS-004 BENJAMIN, S.G., and P. MILLER. An alternative sea level pressure reduction and a statistical comparison of geostrophic wind estimates with observed surface winds. Monthly Weather Review 1 18(10):2099-21 16 (1990). A method for station or grid point reduction of surface pressure to sea level or some other level is presented that shows improvement over the standard reduction method in the western United States. This method (MAPS SLP-Mesoscale Analysis and Prediction System sea level pressure) uses the 700 hPa temperature to estimate an "effective" surface temperature from which the temperature of the hypothetical layer beneath the ground is estimated. The use of this "effective" temperature instead of the observed surface temperature is responsible for the improved reduction since it varies more smoothly over space and lime and is more representative of the temperature variation found above the boundary layer. The MAPS SLP reduction was compared with the standard reduction and altimeter setting reduction in statistical comparisons of geostrophic wind estimates with observed winds and in a case study. A 21 -month comparison between geostrophic and observed winds was made over different geographical regions, times of day, rotation angles and seasons. The results showed that the MAPS SLP reduction performed better than the standard reduction in the western United Stales, but not in other regions wilh generally low elevation. In general, the correlation between sea level geostrophic winds and observed winds was found to be dependent on the Froudc number. A statistical comparison using a smaller sample between MAPS SLP and the Sangstcr geostrophic wind, which is not a station reduction, showed similar skill over the western United States. The case study also showed that the pattern over the western United Stales was more coherent and less anomalous with MAPS SLP than wilh the other reductions. FS-005 BENJAMIN, S.G., and P. STAMUS. Experiments with 1-h assimilation cycles using mesoscale aircraft and surface data. International Association of Meteorology and Atmospheric Physics Symposium on Mesoscale Meteorology: Observational Systems, Analysis and Forecasting, Vienna, Austria, August 21-23, 1991. XX General Assembly of the International Union of Geodesy and Geophysics, 159 (1991). 75 Extended abstract. FS-006 BIRKENHEUER, D. An algorithm for operational water vapor analyses integrating GOES and dual-channel microwave radiometer data on the local scale. Journal of Applied Meteorology 30(6):834-843 (1991). An algorithm for the operational integration of satellite -derived and ground-based passive microwave precipitable-water measurements is presented. The technique merges the two data types by relying on the more accurate ground-based data to correct the bias and scale the satellite field, thus providing an improved meso-beta-scale analysis. The complete algorithm is described from the preparation of the derived satellite imagery, used here as a data source, to the optimization routine used to integrate the data. The technique is now used for a local- scale analysis of the Denver area. One case is presented illustrating the effectiveness of the technique to track a weak moisture gradient through eastern Colorado. Other cases demonstrate the performance of the analysis in varying topography. FS-007 BULLOCK, C.S., and J.A. HAGGERTY. Preliminary results on creating guidance terminal forecasts from gridded numerical model output. Preprints, Fourth International Conference on Aviation Weather Systems, Paris, France, June 24-26, 1991. American Meteorological Society, Boston, 127-134 (1991). No abstract. FS-008 BULLOCK, C.S., and D.S. WALTS. Consideration for the DARE-II design. Preprints, Seventh International Conference on Interactive Information and Processing Systems for Meteorology, Hydrology and Oceanography, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, 152-156 (1991). No abstract. FS-009 3 3 CAIRNS, M.M. DAR E-I Evaluation: Assessment of weather forecasts made using the DAR E-I workstation. NOAA TR ERL 443- FSL 5, 30 pp. (1990). 3 This evaluation of the Denver AWIPS-90 Risk Reduction and Requirements Evaluation, Part I (DAR E-I) system compares the forecast accuracy of severe storm warnings, probability of precipitation (POP), and maximum and minimum temperature forecasts issued before and after the system was installed in the Denver National Weather Service Office (WSFO) in September 1986. Twenty years of POP and temperature forecasts for Denver and Grand Junction, Colorado are compared to those forecasts issued in the year following installation, whereas severe storm warnings issued by tho Denver WSFO for the Colorado Front-Range were evaluated for a three- and five-year period. For this evaluation, tornado warnings showed the most improvement in the false alarm ratio (FAR). Increased lead time and the decreased size of the warning area indicate a marked potential for improved service to the public. Severe thunderstorm warnings also showed similar, but not as noticeable improvements. The probability of detection (POD) scores declined for both tornado and severe thunderstorm warnings. The precipitation forecasts show little change in skill and reliability, while there is suggested improvements in the cool- and warm-season 0-1 hour temperature forecasts after the installation of DAR E-I. FS-010 Chappell, C.F., and P. SCHULTZ. A technique for nowcasting hourly snowfall. Preprints, Fourth International Conference on Aviation Weather Systems, Paris, France, June 24-26, 1991. American Meteorological Society, Boston, 153-156 (1991). No abstract. FS-011 Chaumerliac, N., E. Richard, R. Rosset, and E.C. NICKERSON. Impact of two microphysical schemes upon gas scavenging and deposition in a mesoscale meteorological model. Journal of Applied Meteorology 30(1 ):88-97 (1991). Two widely used microphysical schemes are compared to evaluate their possible impact on wet deposition mechanisms. They are based upon different spectral distributions for raindrops (Marshall-Palmer and lognormal distributions) and use different formulations for the autoconversion and evaporation processes, as well as for the fall velocity of raindrops. A comparative study of these two schemes is carried out for a two-dimensional mountain wave simulation in a mesoscale meteorological model. Differences in the spatial and temporal evolution of microphysical fields are investigated. The two schemes arc compared for simple chemical scenarios: gas dissolution in cloud and rain, gas scavenging by raindrops, and wet deposition. Results contrast the differing behavior of the two schemes in describing processes such as the 76 direct scavenging of gases by raindrops and the release of chemical species back into the atmosphere because of below-cloud evaporation of rain. FS-012 Chaumerliac, N., R. Rosset, and E.C. NICKERSON. Mesoscale modeling of pollutant transport and deposition in case of frontal rain. In Air Pollution Modeling and Its Application VHI, H. van Dop and D.G. Steyn (ed.). Plenum Press, New York, 553-558. Gases emitted in the planetary boundary layer can be transported very efficiently to the free troposphere through vertical motion along a frontal surface. Then, they can dissolve and react with other products within the cloud before being deposited on the ground. A mesoscale numerical model was used to simulate frontogenesis in a moist atmosphere (an evolving Eady wave) in order to study the relative importance of vertical transport and scavenging on the redistribution of different tracers (soluble or insoluble, reactive or nonreactive) in the atmosphere. FS-013 Doswell, C.A., and S.L. BARNES. Comments on "The theoretical, discrete, and actual response of the Barnes Objective Analysis Scheme for one- and two-dimensional fields." Monthly Weather Review 119:1490-1492 (1991). No abstract. FS-014 Foss, F., and J.W. HINKELMAN. Operational aviation service requirements. Preprints, Fourth International Conference on Aviation Weather Systems, Paris, France, June 24-26, 1991. American Meteorological Society, Boston, 202-207 (1991). No abstract. FS-015 Friehe, C.A., W.J. Shaw, D.P. Rogers, K.L. Davidson, W.G. Large, S.A. Stage, G.H. Crescenti, S.J.S. Khalsa, O.K. GREENHUT, and F. Li. Air-sea fluxes and surface layer turbulence around a sea surface temperature front. Journal of Geophysical Research 96(C5):8593-8609(1991). The response of the lower marine atmospheric boundary layer to sharp changes in sea surface temperature was studied in the Frontal Air- Sea Interaction Experiment (FASFNEX) with aircraft and ships measuring mean and turbulence quantities, sea surface temperature, and wave state. Changing synoptic weather on 3 successive days provided cases of wind direction both approximately parallel and perpendicular to a surface temperature front. For the wind perpendicular to the front, both wind over cold-to-warm and warm-to-cold surface temperatures occurred. For the cold-to-warm case, the unstable boundary layer was observed to thicken, with increased convective activity on the warm side. For the warm-to-cold case, the surface layer buoyant stability changed from unstable to neutral or slightly stable, and the sea state and turbulence structure in the lower 100 m were immediately altered, with a large decrease in stress and slowing of the wind. Measurements for this case with two aircraft in formation at 30 and 100 m show a slightly increased stress divergence on the cold side. The turbulent velocity variances changed anisotropically across the front: the streamwise variance was practically unchanged, whereas the vertical and cross-stream variances decreased. Model results, consistent with the observations, suggest that an internal boundary layer forms at the sea surface temperature front. The ocean wave, swell, and microwave radar backscalter fields were measured form several aircraft which flew simultaneously with the low-level turbulence aircraft. Significant reductions in backscatler and wave height were observed on the cold side of the front. FS-016 GOVETT, M. A research-quality radiosonde database for use with advanced data sets. Lower Tropospheric Profiling: Needs and Technologies, Boulder, CO, September 10-13, 1991, NCAR and NOAA/WPL, Boulder, 189-190 (1991). Extended abstract. FS-017 HINKELMAN, J., R. JESUROGA, D. LAW, and A. MARROQUPN. Preliminary results of the detection of clear air turbulence by the Wind Profiler Demonstration Network. Preprints, Fourth International Conference on Aviation Weather Systems, Paris, France, June 24-26, 1991. American Meteorological Society, Boston, 81-89 (1991). No abstract. 77 FS-018 Hudson, E.F., and J.W. HINKELMAN. Aviation experiments and the NOAA Wind Profiler Demonstration Network. Proceedings, 29th Aerospace Sciences Meeting, Reno, NV, January 7-10, 1991. American Institute of Aeronautics and Astronautics, AIAA 91- 0259,5 pp. (1991). No abstract. FS-019 JESUROGA, R.T., J. RAMER, and S. ALBERS. Validation of aviation weather products for the Advanced Traffic Management System. Preprints, Fourth International Conference on Aviation Weather Systems, Paris, France, June 24-26, 1991. American Meteorological Society, Boston, 287-290 (1991). No abstract. FS-020 KELSCH, M. Estimating flash flood potential with radar. Preprints, 16lh Conference on Severe Local Storms and the Conference on Atmospheric Electricity, October 22-26, 1990, Kananskis Park, Alia., Canada. American Meteorological Society, Boston, 621-626 (1990). No abstract. FS-021 LAW, D.C. Effects of precipitation, convection, and waves on NOAA network profilers. Preprints, 25lh International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 43-46 (1991). No abstract. FS-022 LJPSCHUTZ, R.C., G.J. EDWARDS, and D.L. DAVIS. FSL's NEXRAD product interface subsystem. Preprints, Seventh International Conference on Interactive Information and Processing Systems for Meteorology, Hydrology and Oceanography, January 13-18, 1991, New Orleans, LA. American Meteorological Society, Boston, 167-172 (1991). No abstract. FS-023 MAHONEY, J. Climatology of snowfall-event characteristics at Denver. Proceedings, 59th Annual Meeting of the Western Snow Conference, Juneau, Alaska, April 12-15, 1991, Western Snow Conference, 57-66 (1991). No abstract. FS-024 MARROQUIN, A., and B. STANKOV. Diagnostic studies of clear air turbulence in isentropic coordinates. Preprints, Fourth International Conference on Aviation Weather Systems, Paris, France, June 24-26, 1991. American Meteorological Society, Boston, 262-267 (1991). No abstract. FS-025 MCGENLEY, J., and S.C. ALBERS. Validation of liquid cloud water forecasts from the Smith-Feddes method derived from soundings and LAPS analyses. Preprints, Fourth International Conference on Aviation Weather Systems, Paris, France, June 24-26, 1991. American Meteorological Society, Boston, 228-233 (1991). No abstract. 78 FS-026 MCGINLEY, J., S.C. ALBERS, and P.A. STAMUS. Local data assimilation and analysis for nowcasiing. Proceedings, 28ih COSPAR Conference, June 25-July 6, 1990, The Hague, The Netherlands. In Advances in Space Research, Pergamon Press, Oxford, England, 10 pp. (1990). Advances in remote sensing from ground-based and space-bome systems, expanded in-situ observation networks, and increased low-cost computer capability, will allow an unprecedented view of mesoscale weather systems from the local weather office. However, the volume of data from these new instruments, the nonconventional quantities measured, and a frequent operational cycle, require the development of systems to translate this information into products aimed specifically at aiding the forecaster in zero to six hour prediction. An observing network now exists in northeast Colorado that is similar to what a local weather office will have available within 5-7 years. With GOES and TIROS satellites, Doppler radar, wind profilers, and surface mesonet stations, we have a unique opportunity to explore the use of such data in nowcasting weather phenomena. The scheme, called LAPS (the Local Analysis and Prediction System), objectively analyzes data on a high- resolution (10-km), three-dimensional grid. The analyzed fields are used to generate mesoscale forecast products currently aimed a convection and aircraft icing. Substantial skill was demonstrated during a convective forecasting experiment. While preliminary results from the icing experiment indicate improvements are needed with fine detail, the results are useful in an areally averaged sense. FS-027 MCGINLEY, J.A., S.C. ALBERS, and P.A. STAMUS. Validation of a composite index as defined by a real-lime local analysis system. Weather and Forecasting 6(3):337-356 (1991). Advances in remote sensing from earth and space-bome systems, expanded in situ observation networks, and increased low-cost computer capability will allow an unprecedented view of mesoscale weather systems form the local weather office. However, the volume of data from these new instruments, the nonconventional quantities measured, and the need for a frequent operational cycle require development of systems to translate this information into products aimed specifically at aiding the forecaster in 0- to 6-h prediction. In northeast Colorado an observing network now exists that is similar to those that a local weather office may see within 5-7 years. With GOES and TIROS satellites, Doppler radar, wind profilers, and surface mesonet stations, a unique opportunity exists to explore the use of such data in nowcasiing weather phenomena. The scheme, called LAPS (the Local Analysis and Prediction System), objectively analyzes data on a high-resolution, three- dimensional grid. The analyzed fields are used to generate mesoscale forecast products aimed at specific local forecast problems. An experiment conducted in the summer of 1989 sought to test the use of a preconvective index on the difficult problem of convective rain forecasting. The index was configured from surface-based lifted index and kinematically diagnosed vertical motion. The index involved a number of LAPS-derived meteorological fields and the results of the test measured in some sense the quality of those fields. Using radar reflectivity to verify the occurrence or nonoccurrence of convective precipitation, forecasts were issued for three lime periods on each of 62 exercise days. The results indicated that the index was significantly beller than persistence over a range of echo intensities. Skill scores computed from contingency tables indicated that the index had substantial skill in forecasting light convective precipitation with 1- to 3-h lead time. Less skill was shown for heavier convective showers. The skill of the index did not depend strongly on the density of surface data, but was negatively influenced by mountainous terrain. FS-028 MCGUIRK, M.P., and M. Crowe. Wind Profiler Demonstration Network data management activities. Preprints, Seventh International Conference on Interactive Information and Processing Systems for Meteorology, Hydrology and Oceanography, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, 404-410 (1991). No abstract. FS-029 MILLER, P.A., and T.W. SCHLATTER. An evaluation of automated quality control methods designed for use with hourly wind profiler data. Lower Tropospheric Profiling: Needs and Technologies, Boulder, CO, September 10-13, 1991, NCAR and NOAA/WPL, Boulder, 203-204 (1991). Extended abstract. FS-030 MONINGER. W.R. The artificial intelligence shootout:a comparison of severe storm forecasting systems. Eighth Conference on Hydrometeorology, Kananaskis Park, Alta., Canada, October 22-26, 1990. American Meteorological Society, Boston, 1-6 (1990). No abstract. 79 FS-031 MONINGER, W.R., J. Bullas, B. de Lorenzis, E. ELlison, J. Flueck, J.C. McLeod, C. LUSK, P.D. Lampru, R.S. Phillips, W.F. ROBERTS, R. Shaw, T.R. Stewart, J. Weaver, K.C. Young, and S.M. Zubrick. Shootout-89, a comparative evaluation of knowledge- based systems that forecast severe weather. Bulletin American Meteorological Society 72(9):1 339-1 354 (1991). During the summer of 1989, the Forecast Systems laboratory of the National Oceanic and Atmospheric Administration sponsored an evaluation of artificial-intelligence-based systems that forecast severe convective storms. The evaluation experiment, called Shootout-89, took place in Boulder, Colorado, and focused on storms over the northeastern Colorado foothills and plains. Six systems participated in Shootout- 89: three traditional expert systems, a hybrid system including a linear model augmented by a small expert system, an analogue-based system, and a system developed using methods from the cognitive science/judgment analysis tradition. Each day of the exercise, the systems generated 2-9 h forecasts of the probabilities of occurrence of nonsignificant weather, significant weather, and severe weather in each of four regions in northeastern Colorado. A verification coordinator working at the Denver Weather Service Forecast Office gathered ground-truth data from a network of observers. The systems were evaluated on several measures of forecast skill, on timeliness, on ease of learning, and on ease of use. They were generally easy to operate; however, they required substantially different levels of meteorological expertise on the part of their users, reflecting the various operational environments for which they had been designed. The systems varied in their statistical behavior, but on this difficult forecast problem, they generally showed a skill approximately equal to that of persistence forecasts and climatological forecasts. FS-032 Richard, E., P. Mascart, and E.C. NICKERSON. Examples of the role of surface friction in downslope windstorms. Meteorology and Atmospheric Physics, 43, 163-172 (1990). Numerical simulations of four mountain wave events over the Colorado Rockies were carried out with a two-dimensional hydrostatic model including a turbulent mixing parameterization in order to investigate the effect of surface friction. Surface friction was found to play a major role in modulating and even in some cases preventing the wave amplification mechanism from producing severe downslope windstorms. FS-033 SCHLATTER, T.W., and S.G. BENJAMIN. A mesoscale data assimilation system adapted for trajectory calculations over Alaska. First International Symposium on Volcanic Ash and Aviation Safety, Seattle, WA, July 8-12, 1991. U.S. Geological Survey Circular 1065,38-39 (1991). Extended Abstract. FS-034 SCHLATTER, T.W., and J.-M. CARRIERE. Statistics of three-hour forecast error for a real-time, isentropic mesoscale data assimilation system. International Association of Meteorology and Atmospheric Physics Symposium on Mesoscale Meteorology: Observational Systems, Analysis and Forecasting, Vienna, Austria, August 21-23, 1991. XX General Assembly of the International Union of Geodesy and Geophysics, 161 (1991). Extended abstract. FS-035 SCHULTZ, P., and M.K. Politovich. Automated guidance for forecasting conditions conducive to aircraft icing. Preprints, Seventh International Conference on Interactive Information and Processing Systems for Meteorology, Hydrology and Oceanography, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, 492-496 (1991). No abstract. FS-036 SHERRETZ, L. Developing the Aviation Gridded Forecast System. Preprints, Fourth International Conference on Aviation Weather Systems, Paris, France, June 24-26, 1991. American Meteorological Society, Boston, 102-105 (1991). No abstract. FS-037 SLONAKER, R.L., and W. Emery. Convective lid analysis using TOVS. Technical Proceedings, Sixth International TOVS Study Conference, Airlie, VA, May 1-6, 1991, World Meteorological Organization, 468-471 (1991). XO No abstract. FS-038 SMART, J.R., and S.C. ALBERS. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991 American Meteorological Society, Boston, 103-106 (1991). No abstract. FS-039 SMART, J.R., and J.M. BRUNDAGE. Reviewing Meteorological Data on the DARE-II Workstation. Preprints, Seventh International Conference on Interactive Information and Processing Systems for Meteorology, Hydrology and Oceanography, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, 157-163 (1991). No abstract. FS-040 SMITH, J.K., and R.C. LTPSCHUTZ. Performance of the NEXRAD precipitation algorithms in Colorado during 1989. Eighth Conference on Hydrometeorology, Kananaskis Park, Alia., Canada, October 22-26, 1990. American Meteorological Society, Boston, 184-188 (1990). No abstract. FS-041 SMITH, T.L., and S.G. BENJAMIN. Impact of network profiler data on a hybrid data assimilation system. Lower Tropospheric Profiling: Needs and Technologies, Boulder, CO, September 10-13, 1991, NCAR and NOAA/WPL, Boulder, 189-190 (1991). Extended abstract. FS-042 SMITH, T.L., and S.G. BENJAMIN. The evolution of the regional severe-storm environment as viewed by a hybrid isentropic-sigma assimilation system. Preprints, 16th Conference on Severe Local Storms and the Conference on Atmospheric Electricity, Kananskis Park, Alta., Canada, October 22-26, 1990. American Meteorological Society, Boston, 504-509 (1990). No abstract. FS-043 SZOKE, E.J. Eye of the Denver cyclone. Monthly Weather Review 1 19(5): 1283-1 292 (1991). Observation of an overcast of low cloudiness on a Denver Cyclone day revealed a circular area of clearing or "eye" at the approximate center of the mesoscale circulation. The eye passed close to an automated observing station, providing a time series of data that shows the relationship of the circulation to the cloud-free area. Conditions present in the lower troposphere are examined and compared to conclusions from recent modeling results that suggest the causes of the Denver Cyclone. FS-044 SZOKE, E.J. The use of Doppler radar in the short-range forecasting of snowfall in northeastern Colorado. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 71-74 (1991). No abstract. FS-045 TOLLERUD, E.I., K.W. HOWARD, and X.-P. Zhong. Jet streaks and their relationship to heavy precipitation in Colorado Front Range winter storms. Preprints, First International Symposium on Winter Storms, January 14-18, 1991, New Orleans, LA. American Meteorological Society, Boston, 97-100 (1991). No abstract. 81 FS-046 TOLLERUD, E.I., and D.M. RODGERS. The seasonal and diurnal cycle of mesoscale convection and precipitation in the central United Stales: interpreting a 10-year satellite-based climatology of mesoscale convective complexes. Preprints, Seventh Conference on Applied Climatology, September 10-13, 1991, Salt Lake City, UT. American Meteorological Society, Boston, 63-70 (1991). No abstract. FS-047 TOLLERUD, E.I., and X.P. Zhong. Differences in the environments of high- and low-rain producing mesoscale convective complexes. Preprints, Eighth Conference on Hydrology, Kananaskis Park, Aha., Canada, October 22-26-1990, American Meteorological Society, Boston, 62-67 (1990). No abstract. FS-048 VAN DE KAMP, D.W., W.F. ROBERTS. Network monitoring functions of the Profiler Control Center. Preprints, Seventh International Conference on Interactive Information and Processing Systems for Meteorology, Hydrology and Oceanography, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, 88-91 (1991). No abstract. FS-049 WEBER, B.L., D.B. WUERTZ, R.G. STRAUCH, DA. MERRITT, D.C. Law D. VAN DE KAMP, R.B. CHADWTCK, M.H. ACKLEY, M.C. BARTH, N.L. ABSHIRE, PA. MILLER, and T.W. SCHLATTER. Preliminary evaluation of the first NOAA Demonstration Network Wind Profiler. Journal of Atmospheric and Oceanic Technology 7(6):909-918. The first wind profiler for a demonstration network of wind profilers recently passed the milestone of 300 h of continuous operation. The horizontal wind component measurements taken during that period are compared with the WPL Platteville wind profiler and the NWS Denver rawinsonde. The differences between the network and WPL wind profilers have standard deviations of 2.30 m $~ and 2.16 m s" for the u- and v-components, respectively. However, the WPL wind profiler ignores vertical velocity, whereas the network radar measures it and removes its effects from the u- and v-component measurements. The differences between the network wind profiler and the NWS rawinsonde (separated spatially by about 50 km) have standard deviations of 3.65 m s and 3.06 m s for the u- and v-components, respectively. These results are similar to those found in earlier comparison studies. Finally, the new network wind profiler demonstrates excellent sensitivity, consistently reporting measurements at all heights msl from 2 to nearly 18 km with very few outages. X2 GEOPHYSICAL FLUID DYNAMICS LABORATORY GF-001 Bard, E., M. Arnold, J.C. Duplessy, P. Maurice, and J.R. TOGGWEILER. Bomb UC in the Indian Ocean measured by accelerator mass spectroscopy: oceanography implications. Radiocarbon 31(3):5 10-522 (1991). AMS HC measurements on samples collected in the tropical-equatorial Indian Ocean during the INDIGO program (leg II, 1986) are presented and compared with /3-counting results obtained under both INDIGO program and GEOSECS expedition in the Indian Ocean (1978). The most significant observation is a doubling of the bomb-"C inventory and mean penetration depth in the equatorial zone. Based on hydrologic considerations, two hypotheses can be proposed: 1) direct influx of Pacific mid-latitude waters through the Indonesian archipelago and 2) advection and/or mixing with Mode Water from the southern gyre of the Indian Ocean. Results obtained with a general circulation model of the ocean suggest that the influx from the Pacific is important in the upper 300m and that below 500m the bomb-'*C budget is dominated by Mode Water advection. GF-002 Bretherton, F.P., K. BRYAN, J.D. Woods, Time-dependent greenhouse-gas-induced climate change. In Climate Chan£e. the IPCC Scientific Assessment, J.T. Houghton, G.J. Jenkins, and J.J. Ephraums (eds.). Cambridge University Press, 179-193 (1991). No abstract. GF-003 BROCCOLI, A.J., and S. MANABE. Can existing climate models be used to study anthropogenic changes in tropical cyclone climate? Geophysical Research Letters 17(1 1): 1917-1920 (1990). The utility of current generation climate models for studying the influence of greenhouse warming on the tropical storm climatology is examined. A method developed to identify tropical cyclones is applied to a series of model integrations. The global distribution of tropical storms is simulated by these models in a generally realistic manner. While the model resolution is insufficient to reproduce the fine structure of tropical cyclones, the simulated storms become more realistic as resolution is increased. To obtain a preliminary estimate of the response of the tropical cyclone climatology, CO^ was doubled using models with varying cloud treatments and different horizontal resolutions. In the experiment with prescribed cloudiness, the number of storm-days, a combined measure of the number and duration of tropical storms, undergoes a statistically significant increase in the doubled-CG, climate. In contrast, a smaller but significant reduction of the number of storm-days is indicated in the experiment with cloud feedback. In both cases the response is independent of horizontal resolution. While the inconclusive nature of these experimental results highlights the uncertainties that remain in examining the details of greenhouse-gas induced climate change, the ability of the models to qualitatively simulate the tropical storm climatology suggests that they are appropriate tools for this problem. GF-004 BRYAN, K., and R. STOUFFER. A note on Bjerknes' hypothesis for North Atlantic variability. Journal of Marine Systems 1:229-241 (1991). On decadal time-scales the historical surface temperature record over land in the Northern Hemisphere is dominated by polar amplified variations. These variations are coherent with SST anomalies concentrated in the Northwest Atlantic, but extending with lesser amplitude into the North Pacific as well. Bjerknes suggested that multi-year SST anomalies in the subpolar North Atlantic were due to irregular changes in the intensity of the thermohaline circulation. In support of the Bjerknes hypothesis there is evidence that winter overturning in the Labrador Sea was suppressed for a brief period from 1967-1969 by a cap of relative fresh water at the surface. Cause and effect are unclear, but this event was associated with a marked cooling of the entire Northern Hemisphere. The difference in SST averaged over the Northern Hemisphere oceans and SST averaged over the Southern Hemisphere oceans from the equator to 40°S is coherent with Sahel summer rainfall on decadal time scales. Empirical evidence is supported by numerical experiments with the British Meteorological Office atmospheric climate model which simulate augmented monsoonal rainfall in the Sahel region of Africa in response to realistic warm SST anomalies in the Northwest Atlantic. A coupled ocean-atmosphere global model exhibits two equilibrium climate states. One has an active thermohaline circulation in the North Atlantic and the other does not. The two climate states provide an extreme example which illustrates the type of large scale air interaction Bjerknes visualized as a mechanism for North Atlantic climate variability on decadal time-scales. 83 GF-005 Detwiler, A., and V. Ramaswamy. Radiative heating profiles in simple cirrus cloud systems. Journal of the Atmospheric Sciences 47(18):2167-2176(1990). Results from one-dimensional cirrus cloud model simulations in the absence of upward velocities are used to show that the growth/sublimation of the ice particles in the cloud, and the fact that they are falling, can be important factors in determining the net heating rate in the air through which these clouds settle. The vertical profiles of the heating rate inside the cloud are stretched as a result of the settling of the cloud. Results for clouds at various altitudes in both midlatitude and tropical atmospheres are compared. GF-006 Ellingson, R.G., J. Ellis, and S. FELS. The intercomparison of radiation codes used in climate models: Long wave results. Journal of Geophysical Research 96(D5):8929-8953,(1991). An international program of intercomparison of radiation codes used in climate models has been initiated because of the central role of radiative processes in many proposed climate change mechanisms. During the past 6 years, results of calculations from such radiation codes have been compared with each other, with results from the most detailed radiation models (line-by-line models) and with observations from within the atmosphere. Line-by-line model results tend to agree with each other to within 1 %; however, the intercomparison shows a spread of 10-20% in the calculations of radiation budget components by the less detailed climate model codes. The spread among the results is even larger (30-40%) for the sensitivities of the codes to changes in radiatively important variables, such as carbon dioxide and water vapor. The analysis of the model calculations shows that the outliers to many of the clear-sky calculations appear to be related to those models that have not tested the techniques used to perform the integration over altitude. When those outliers fluxes at the atmospheric boundaries, about +5 % for the flux divergence for the troposphere, and to about +5 % for the change of the net flux at the tropopause as CO, doubles. However, this good agreement does not extend to the majority of the models currently used in climate models. The lack of highly accurate flux observations from within the atmosphere has made it necessary to rely on line-by-line model results for evaluating model accuracy. As the intercomparison project has proceeded, the number of models agreeing more closely with the line-by-line results has increased as the understanding of these various parameterizations has improved and as coding errors have been discovered. The most recent results indicate that several climate model technniques are in the marginal range of (relative) accuracy for longwave flux calculations for many climate programs. However, not all such models will give such accuracy. It is recommended that a code not be accepted to provide such accuracy until it has made comparisons to the line-by-line results of this study. The data necessary to make such comparisons are included herein. However, uncertainties in the physics of line wings and in the proper treatment of the water vapor continuum make it impossible for the line-by-line models to provide an absolute reference for evaluating less-detailed model calculations. A dedicated field measurement program is recommended for the purpose of obtaining accurate spectral radiance rather than integrated fluxes as a basis for evaluating model performance. GF-007 Feigelson, E.M., B.A. Fomin, I. A. Gorchakova, E.V. Rozanov, M.D. SCHWARZKOPF, Y.M. Timofeyev, A.N. TroUenko. Calculation of longwave radiation fluxes in atmospheres. Journal of Geophysical Research 96(D5):8985-9001 (1991). A technique for the computation of longwave radiative quantities using the line-by-line approach has been developed in the Soviet Union. The method has been applied to obtain fluxes and cooling rates for standard atmospheric profiles used in the Intercomparison of Radiation Codes Used in Climate Models (ICRCCM) sponsored by the World Meteorological Organization. The sensitivity of the result to changes in the vertical quadrature scheme, the angular integration, and the spectral line shape is evaluated. Fluxes and cooling rates in the troposphere are in general agreement with those obtained with different line-by-line models. Results from parameterized models, including a wideband statistical model and one employing the integral transmission function, have been compared to the line-by-line results. Flux errors in the simplified schemes are of the order of 10 W/m2. The sensitivity of these models to changes in atmospheric profiles, or to an increase in C02 amount, is similar to that of the line-by-line calculations. GF-008 FELS, S.B., J.T. Kiehl, A. A. Lacis, and M.D. SCHWARZKOPF. Infrared cooling rate calculations in operational general circulation models: comparisons with benchmark computations. Journal of Geophysical Research 96(D5):9105-9120(1991). As part of the Intercomparison of Radiation Codes in Climate Models (ICRCCM) project, careful comparisons of the performance of a large number of radiation codes were carried out, and the results compared with those of benchmark calculations. In this paper, we document the performance of a number of parameterized models which have been heavily used in climate and numerical prediction research at three institutions: Geophysical Fluid Dynamics Laboratory (GFDL), National Center for Atmospheric Research (NCAR), and Goddard Institute for Space Studies (GISS). X4 GF-009 Fouquart, Y., B. Bonnel, and V. Ramaswamy. Intel-comparing shortwave radiation codes for climate studies. Journal of Geophysical Research 96(D5):8955-8968 (1991). As a second step of the international program of Intercomparison of Radiation Codes Used in Climate Models (1CRCCM), an intercomparison of shortwave radiation models was initiated. Among the 26 codes that participated in the comparison were very detailed (line-by-line), narrow-band (high-spectral resolution), as well as highly parameterized flow-spectral resolution) models. A considerable spread was detected in the response of these models to a wet of well-defined atmospheric profiles. Substantial discrepancies exist among models even for the simplest case of pure water vapor absorption with standard deviation ranging from 1 % to 3 % for the downward fluxes at the surface and from 6% to 1 1 % for the total atmospheric absorption. The divergences in downward surface flux increase to nearly 4% when all absorbers and the molecular scattering are considered. In cloudy conditions the divergences range from 4% to 10%, depending on the cloud optical thickness. Another major uncertainty that has been identified is the spectral averaging of the scattering properties which can result in very significant errors for low spectral resolution codes. Since these errors appear to be systematic, they may induce unrealistic feedback mechanisms in numerical climate models. The amplitude of the differences between models is in many cases larger than the accuracy required for the achievements of several objectives of the World Climate Reearch Program. While reference solutions for the absorption and scattering in atmospherics can be obtained based on the state-of-the-art spectroscopic knowledge and rigorous computational techniques, the absolute tests of the validity of the radiation algorithms would be comprehensive field experiments in which the radiative and all relevant atmospheric parameters are measured to a high degree of accuracy. GF-010 Galperin, B., and G.L. Mellor. A time-dependent, three-dimensional model of the Delaware Bay and river system. Part I: Description of the model and tidal analysis. Estuarine. Coastal and Shelf Science 31(3):231-253 (1990). A three-dimensional, time-dependent numerical model is used to simulate the dynamics and thermodynamics of Delaware Bay, River and adjacent continental shelf. This study describes the first attempt to model an estuary and the contiguous shelf as a coupled hydrodynamic and thermodynamic system. Here, in Part 1, a description of the model, boundary conditions and forcing information is provided. Numerical results are compared with surface elevation data at several locations throughout the Bay and the River, as well as with the observations collected by the National Ocean Service during their 1984-85 circulatory study. It is shown that a vertically-integrated, two- dimensional version of the model predicts realistic amplitudes but with some phase error. The full three-dimensional model reduces the phase error but underpredicts the tidal range; this is due to the higher values of horizontal viscosity required by the three-dimensional model. The model accounts for non-linear, shallow-water effects and reproduces the observed amplification of the high-frequency tidal components from the mouth of the Bay to the head of the River at Trenton. GF-011 Galperin, B., and G.L. Mellor. A time-dependent, three-dimensional model of the Delaware Bay and River system. Part II: Three- dimensional flow fields and residual circulation. Estuarine. Coastal and Shelf Science 31(3):255-281 (1990). The three-dimensional model of Delaware Bay, River and adjacent continental shelf was described in Part I. Here, Part 2 of this two- part paper demonstrates that the model is capable of realistic simulation of current and salinity distributions, tidal cycle variability, events of strong mixing caused by high winds and rapid salinity changes due to high river runoff. The 25-h average subtidal circulation strongly depends on the wind forcing. Monthly residual currents and salinity distributions demonstrate a classical two-layer estuarine circulation wherein relatively low salinity water flows out at the surface and compensating high salinity water from the shelf flows at the bottom. The salinity intrusion is most vigorous along deep channels in the Bay. Winds can generate salinity fronts inside and outside the Bay and enhance or weaken the two-layer circulation pattern. Since the portion of the continental shelf included in the model is limited, the model shelf circulation is locally wind-driven and excludes such effects as coastally trapped waves and interaction with Gulf Stream rings; nevertheless, a significant portion of the coastal elevation variability is hindcast by the model. Also, inclusion of the shelf improves simulation of salinity inside the bay compared with simulations where the salinity boundary condition is specified at the mouth of the Bay. GF-012 Garner, S.T. The nongeostrophic structure of baroclinic waves and its relation to fronts and jet streaks. Journal of the Atmospheric Sciences 48(1): 147-162 (1991). Some fundamental properties of nongeostrophic baroclinic waves are examined by solving the equations of motion linearized about Eady's basic state at the next order of balance beyond quasi-geostrophic (QG) theory. The study fits into a general effort to broaden the view of "slow-manifold" behavior. The specific motivation is to identify balanced properties of surface and upper-tropospheric frontal regions that are filtered from both the QG and the semigeostrophic models. Among the questions to be answered are whether along front flow is subgeostrophic or supergeostrophic, and whether the ageostrophy is realized primarily as a velocity or pressure correction of the QG solution. A rudimentary model of jet streaks is constructed from nongeostrophic neutral waves in an attempt to reproduce along-jet ageostrophic velocities and propagation speeds more realistically than in existing models. Past work has concentrated on correcting phase speeds and growth rates for higher-order balanced effects. These results are extended by using a more appropriate solvability condition near 85 the short-wave cutoff and by considering the detailed structure of the nongeostrophic modes. The eigenvalue corrections are interpreted physically in the framework of a generalized potential vorticity inversion problem with sources determined at the QG level. It is shown that ageostrophic shear in the nondivergent (alongfront) wind affects the time dependence primarily indirectly 1, by tilting the basic isentropes in the meridional direction and setting up an anomaly pattern in the QG potential vorticity field. This has some of the same consequences as shortening the horizontal scale in the QG model. GF-013 Hakkinen, S. and G.L. Mellor. One hundred years of Arctic ice cover variations as simulated by a one-dimensional, ice-ocean model. Journal of Geophysical Research 95(C9):15,959-15,969(1990). A one-dimensional ice-ocean model consisting of a second moment, turbulent closure, mixed layer model and a three-layer snow-ice model has been applied to the simulation of Arctic ice mass and mixed layer properties. The results for the climatological seasonal cycle are discussed first and include the salt and heat balance in the upper ocean. The coupled model is then applied to the period 1880-1985, using the surface air temperature fluctuations from Hansen et al. (1983) and from Wigley et al. (1981). The analysis of the simulated large variations of the Arctic ice mass during this period (with similar changes in the mixed layer salinity) shows that the variability in the summer melt determines to a high degree the variability in the average ice thickness. The annual oceanic heat flux from the deep ocean and the maximum freezing rate and associated nearly constant mimimum surface salinity flux did not vary significantly interannually. This also implies that the oceanic influence on the Arctic ice mass is minimal for the range of atmospheric variability tested. GF-014 Hakkinen, S. Models and their applications to polar oceanography. In Polar Oceanography. W. Smith (ed.). Academic Press, 335-384 (1990). No abstract. GF-015 Kantha, L.H., and A. ROSATI. The effect of curvature on turbulence in stratified fluids. Journal of Geophysical Research 95(C1 1):20,313-20,330(1990). The influence of streamline curvature on small-scale turbulence and vertical mixing in stratified fluids is the subject of this study. The roles of curvature and stratification in enhancing and suppressing turbulent mixing are explored using second-moment closure for turbulence. Governing equations for second moments are expressed in generalized orthogonal curvilinear coordinates, from which, through a series of approximations, simplified expressions are derived for second moments in the limit of small streamline curvature. The governing equations are then used to obtain a quasi-equilibrium turbulence model suited for application to atmospheric and oceanic mixed layers. A typical model application is illustrated by simulation of stratified flows over two-dimensional, idealized mountains and valleys. The limit of local equilibrium is further invoked to derive semi-analytical results for the enhancement and suppression of vertical turbulent mixing under the combined influence of stratification and curvature. It is shown that stabilizing curvature can drastically suppress turbulence even when the stratification is strongly destabilizing. Conversely, under strong stable stratification that would otherwise lead to curvature is also shown to significantly modify the Monin-Obukhov similarity laws for momentum and heat fluxes in the constant flux region of the atmospheric boundary layer. Finally, the need for observational data on curvature effects on mixing in stratified flows either in the laboratory or in flows over topography in the oceans and the atmosphere is highlighted. GF-016 Karoly, D.J. , and D.S. Graves. On data sources and quality for the Southern Hemisphere stratosphere. In Dynamics, Transport and Photochemistry in the Middle Atmosphere of the Southern Hemisphere. A. O'Neill (ed.). NATO ASI Series C321, Kluwer Academic Press, 19-32(1991). No abstract. GF-017 KURIHARA, Y., M.A. BENDER, R.J. ROSS, R.E. TULEYA. Prediction experiments of Hurricane Gloria (1985) using a multiply nested movable mesh model. Monthly Weather Review 1 18(10) :2 186-2 198 (1990). The prediction capability of the GFDL triply nested, movable mesh model, with finest grid resolution of 1/16 degree, was investigated using several case studies of Hurricane Gloria (1985) during the period that the storm approached and moved up the east coast of the United States. The initial conditions for these experiments were interpolated from an NMC T80 global analysis at 0000 25 September and 1200 UTC 22 September. The integrations starting from 0000 UTC 25 September were run 72 h, while those starting on 1200 UTC 22 September were run 132 h. The lateral boundary conditions were obtained from either an integration of the NMC T80 forecast model or Xft the T80 global analysis, or were fixed to the initial value. The model's predicted track of Gloria for each integration was compared against the best track determined by the National Hurricane Center (NHC). For the case starting from 0000 UTC 25 September using a forecasted boundary condition, the model successfully forecasted significant acceleration of the storm's movement after 48 h. The 72 h forecast error was about 191 km, compared to 480 km for the official track forecast made by the NHC. To examine the model's skill in simulating the storm structure, distributions of the low level meximum wind and total storm rainfall during passage of the model storm are shown and compared with observed values. The model successfully reproduced many observed features such as the occurrence of strong winds well east of the storm center, with an abrupt decrease of the wind field along the coastline. When the storm track was accurately forecasted, the total storm rainfall amounts agreed well with the observed values. In both the model integration and observations, a significant structural change took place as the storm accelerated toward the north with little significant precipitation occurring south of the storm center and heavy precipitation spreading well north of the storm. It appears that the gross features of the structure of the storm's outer region resulted from the interaction of the vortex with its environment. Sensitivity of the model forecast to the lateral boundary condition and the horizontal resolution was also investigated. The storm's track error was greatly affected after the boundary error propagated by advection to the storm region. The impact of the horizontal resolution on the forecast was such that the model with one degree resolution produced a fairly good track forecast up to 48 h, but failed to simulate some of the main structural features. In the experiments starting from the 0000 UTC September 25 initial field, the interior storm structure did not develop, and the storm exhibited too large a radius of maximum wind throughout the integration. However, the integrations starting from 1200 UTC September 22 developed a more intense storm, with a more realistic radius of maximum wind. These differences were due to the spinup time necessary for the storm to develop in the model when starting from a coarse resolution global analysis which did not adequately resolve the fine structure of the storm interior. This indicates the importance of proper specification of the storm in the initial field. GF-018 Lau, K-H. An observational study of tropical summertime synoptic scale disturbances. Ph.D. Dissertation, Princeton University, Princeton, NJ., 243 pp. (1990). The distribution, spectral properties, three-dimensional structure, and propagation characteristics of tropical synoptic-scale transients during the northern summer are studied with twice daily ECMWF global gridded analyses. Lag-correlation and regression statistics of the synoptic-scale tropical fluctuations are examined. Sites of active transient activity are identified with enhanced vorticity variance, teleconnectivity and temporal coherence. Most of these tropical disturbances are found to travel west/northwestward, with the eastern and western portions of each active site being characterized by growth and decay of the transient disturbances, respectively. Transient activity throughout the tropics is also investigated using Extended Empirical Orthogonal Function (EEOF) techniques. Using the EEOF time coefficients, the space-time evolution of selected meteorological variables for the disturbances in various tropical regions are composited. The relative importance of different dynamical processes in the local vorticity, eddy enstrophy and kinetic energy balances are examined. While moist convection is the most important process in the enstrophy and kinetic energy balances for the western pacific and Indian disturbances, barotropic processes (conversion of enstrophy and kinetic energy from the time-mean flow to the transient eddies) also contribute significantly to these maritime fluctuations. For the North African disturbances found along the southern Sahara, baroclinic mean flow to eddy conversion of available potential energy is identified as the most important energy source. Relationships between synoptic- scale transients and severe cyclonic vortex-like systems are studied. By tracking local relative vorticity maxima in successive times and comparing them with tropical storm records in corresponding periods, we find that about 20-30% of the tracked disturbances in the western Pacific develop into tropical storms. The summertime transient activity in a GFDL 30-wavenumber general circulation model has also been analyzed. As in observations, strong transient activity is identified in the vicinity of the simulated summer monsoon troughs. However, the model transient activity appears to be rather sensitive to variations in the low-level currents simulated in the general circulation model. Finally, relationships between the western Pacific transient disturbances and slower-varying fluctuations in the outgoing longwave radiation and vorticity fields are examined. GF-019 Lau, K-H., and N.-C. LAU. Observed structure and propagation characteristics of tropical summertime synoptic scale disturbances. Monthly Weather Review 11 8(9): 1888-1913 (1990). The three-dimensional structure and propagation characteristics of tropical synoptic scale transients during the northern summer are studied with twice daily ECMWF global gridded analyses for the 1980-1987 period. Regions of enhanced variability in relative vorticity at 850 mb are identified in the western Pacific, eastern Pacific, Bay of Bengal/northern India and eastern Atlantic/western Africa sectors. Dominant spectral peaks with time scales ranging from 3 to 8 days are noted in the power spectra for these locations. The lag-correlation and regression statistics of tropical fluctuations with synoptic time scales are examined. Strong teleconnectivity and temporal coherence are found over all of the active sites with enhanced vorticity variance, as well as over the western Atlantic/Caribbean and the Indochinese Penisular. These results indicate that a substantial amount of synoptic scale variability in the topics is associated with propagating wavelike disturbances that remain coherent over several days. The disturbances in all active regions tend to travel west/ northwestward. The eastern portion of each active site is characterized by rapid growth of the disturbances, whereas decay typically occurs in the western portion. The transient behavior throughout the tropics is also investigated using Extended Empirical Orthogonal Function (EEOF) techniques. The sites of the EEOF coefficients as a reference, the temporal evolution as well as the horizontal and vertical structure of the disturbances occurring in each active region are delineated by composites of selected meteorological variables. Well-defined changes in vorticity, vertical velocity, temperature and humidity at various tropospheric levels, as well as convective activity (deduced from the outgoing longwave radiation field), 87 are discernible in the disturbances at various sites. Phase relationships among different variables are interpreted in terms of dynamical and physical processes operating within the disturbances. The horizontal phase tilt of the fluctuations and their positions relative to the ambient mean circulation suggest a tendency for kinetic energy transfer from the quasi-stationary flow to the transient eddies. Most of the findings reported here are in accord with previous investigations based on different analysis tools and more limited datasels. Whereas considerable similarities are noted among disturbances occurring over various active maritime sites the perturbations over central and western Africa exhibit structural characteristics that are unique to that region. Specifically, two propagation tracks are identified in the African sector. The northern track along southern Sahara consists mostly of eddies commonly found over arid zones, with ascent of warm and dry air over surface troughs. The southern track is collocated with the climatological rainfall maximum at about 10°N, and is associated with moist convective systems. GF-020 LAU, N.-C, and M.J. NATH. A general circulation model study of the atmospheric response to extratropical SST anomalies observed in 1950-79. Journal of Climate 3(9):965-989 (1990). A 30-year experiment with an atmospheric general circulation model has been performed. The lower boundary condition at all oceanic grid points between 30°S and 60°N has been prescribed to follow the observed month-to-month variation of the sea surface temperature (SST) field during the 1950-79 period. Much of the model diagnosis presented here pertains to the midlatitude atmospheric response to recurrent SST patterns in the North Pacific and North Atlantic in winter. The principal modes of variability of the seasonally averaged 515 mb height and SST fields have been identified using rotated principal component (RPC) analysis. The extreme of the first atmospheric mode reside over the North Atlantic and Eurasia, whereas the second mode is associated with height anomalies in the North Pacific/North American sector. Cross-correlation analysis reveals that these two atmospheric modes are linked to leading patterns of the SST field in the North Atlantic and North Pacific, respectively. It is also demonstrated that the extreme in leading RPC patterns of the SST field in the northern oceans are almost coincident with the sites of maximal covariability between the SST and 515 mb height fields. Regression charts of selected model parameters versus the SST variations off the Newfoundland coast and northwest of Hawaii have been constructed. These two reference maritime sites have been identified by the RPC and cross-correlation analyses as being correlated with the strongest atmospheric signals. The model fields examined in this manner include the geopotential height at various pressure levels, precipitation, heat flux across the air-sea interface, as well as temporal variance and covariance statistics. These regression maps indicate that the atmospheric response to midlatitude SST anomalies has an equivalent barotropic structure. The presence of SST perturbations in the extratropics are associated with displacements of the storm track axes, and with relocations of the midlatitude rainbelts and preferred sites of heat transfer from the underlying ocean. The changes in the locality of synoptic scale eddy activity are accompanied by alterations in the transient eddy forcing of the quasi-stationary flow. The geopotential height tendencies associated with these anomalous eddy effects exhibit a positive spatial correlation with the seasonally averaged, downstream atmospheric response. The time scale for the eddy induced tendencies to produce such seasonal height anomalies is on the order of several days. These findings suggest that the transient disturbances act as an essential intermediary between the extratropical SST forcing and the time-mean atmospheric response. The principal atmospheric anomaly pattern in the North Atlantic/Eurasian sector exhibits substantial correlations with SST fluctuations in the tropical South Atlantic; whereas oceanic anomalies in the equatorial Pacific are only weakly associated with atmospheric circulation changes in the North Pacific/North American region. The temporal lead/lag relationships between the simulated atmospheric anomalies and the prescribed SST changes have been explored. GF-021 Lee, S. Baroclinic wave pockets in models and observations. Ph.D. Dissertation, Princeton University, Princeton, NJ. 214 pp. (1991). Coherent baroclinic wave packets are found in a hierarchy of models of nonlinear baroclinic instability-a two-layer quasi-geostrophic (QG) model on a /3-plane, a two level primitive equation (PE) model, and a general circulation model (GCM) - as well as in observations from the Southern Hemisphere (SH). The flows are chaotic but the packet itself can remain remarkably coherent, despite the complex evolution of the flow within the packet. In both QG and PE models, the packets become more robust as the supercriticality of the flow is reduced. Consistent with the model results, the packets are more often found in the summer season of the SH due to its weaker baroclinicity than in winter. In both the models and the observations, the packets move with a group velocity that is greater than the phase speed of the individual disturbances, and exhibit a downstream development. The structure of the baroclinic waves in the packet as a function of longitude resembles the life-cycles of sinusoidal baroclinic waves as a function of time. In the weakly nonlinear flow of the QG model, we illustrate direct analogies between the two in terms of eddy and mean flow evolution. More than one packet can exist in the domain at the same time. In a fully nonlinear flow, experiments with the QG model using an unrealistically long channel demonstrate that the number of packets increases in a systematic way as the length of the channel increases. In the weakly nonlinear flow, however, the existence of the packet depends on the quantization of the zonal wavenumber: only if there are two unstable zonal waves whose linear growth rates are comparable to each other do arbitrary small perturbations emerge into coherent wave packets. A qualitative comparison is made with the solutions of a nonlinear Schrodinger equation. As predicted by the solution, there is a negative correlation between the maximum amplitude of the packet and the half-width of the packet. This correlation diminishes as the flow becomes chaotic, even if the coherent packet remains a salient feature of the flow. The relationship between the nonlinear baroclinic wave packets and the climatological storm tracks is discussed. The velocity of the packets seems to be modulated by stationary waves. It is unclear, however, to what extent this kind of modulation of the wave packet can account for the location of the storm track. XX GF-022 Lee, S., and I. HELD. Subcritical instability and hysteresis in a two-layer model. Journal of the Atmospheric Sciences 48(8):1071- 1077 (1991). A two-layer quasi-geostrophic model forced by surface friction and radiative relaxation to a jetlike wind profile can exist in either a wave-free state or in a finite-amplitude wave state, over a substantial region of the model's parameter space. The friction on the lower layer must be much stronger than the thermal relaxation, and the upper layer must be nearly inviscid, for this behavior to be observed. Consistent with this behavior, weakly unstable waves are found that do not stabilize the flow; instead, their growth rate increases with wave amplitude. We attempt to provide a physical explanation for this behavior in terms of 1) the competition between the stabilizing effect of the lower-layer potential vorticity fluxes and the destabilizing effect of nonlinear critical layer formation associated with the upper-layer fluxes, and 2) the tendency of surface drag to restore the vertical shear at the center of the jet by damping the surface westerlies generated by the baroclinic instability. GF-023 MANABE, S. Studies of glacial climates by coupled atmosphere-ocean models: How useful are coupled models? In Global Change cif the Past. R.S. Bradley (ed.). UCAR Office for Interdisciplinary Earth Studies, Boulder, CO., 421-448 (1991). No abstract. GF-024 Matano, R.P. A numerical study of the circulation in the South Atlantic Ocean. Ph.D. Dissertation, Princeton University, Princeton, NJ. 157 pp. (1990). This thesis is an analysis of the circulation of the South Atlantic Ocean. The starting point, in chapter two, is a diagnostic numerical experiment with a three-dimensional model, using observed hydrographic data as initial conditions. In chapter three a heat budget reveals that the South Atlantic gains, at least, half of the heat that it exports to higher latitudes, from the conversion of intermediate into surface waters through interaction with the atmosphere. This result contrast with the most widely accepted hypothesis that the South Atlantic gains heat through eddies detached from the Agulhas Current. This chapter also includes a study of vorticity budgets which serve to explain some of the differences noted in the circulation of the subtropical basin and the Southern Ocean. Chapter four deals with the separation of the Brazil current from the coast and its observed variability. It is found that a full primitive equation model at first separated at tahe correct location, 40°S, but then, after three years, drifted to 47°S. A sensitivity study led to the conclusion that the separation is mostly dominated by the northward momentum of the Malvinas Current. If the flow distribution at the Drake Passage is adjusted so that the transport of the Malavinas Current is increased, then, the separation latitude is significantly improved. The seasonal variation of the separation latitude is also studied. It is found, that due to the wind forcing, the transport of the Brazil Current may be higher during the southern hemisphere summer than during the winter. This result is consistent with the observations that shown a more northward separation during the winter than during the summer. Chapter five tries to explain one of the most conspicuous chracteristics of the meanders of the western boundary currents after they leave the coast, that is, its rapid offshore decay. It is shown, through analytical arguments as well as numerical experiments, that it is possible that this decay is due to the presence of critical layers introduced by the meridional shear of the currents. GF-025 Mellor, G.L., and T. Ezer. A Gulf Stream model and an altimetry assimilation scheme. Journal of Geophysical Research 96(C5):8779- 8795 (1991). A continuous data assimilation scheme and a multilayer, primitive equation, numerical model are described. The model is an eddy- resolving, coastal ocean model that has been extended to include the Gulf Stream region. It has complete thermohaline dynamics, a bottom- following sigma, vertical coordinate system, and a coastal-following, curvilinear orthogonal, horizontal coordinate system. Calculated model fields are used to provide a model climatology and correlations between subsurface temperature and salinity anomalies and surface elevation anomalies. An optimal interpolation method, the surface to subsurface correlations, and estimated model and data errors are the basis of the assimilation technique. Altimetry anomaly data extracted from the model calculations according to the Geosat orbital schedule are used to test the assimilation scheme and to provide nowcasts and forecasts. Sensitivity studies are performed to test the effects of various parameters of the scheme. It is found that the scheme is less efficient in the shallow continental shelf area than in the deeper regions of the model. The results show significant nowcast skill, with area-averaged rms error for surface elevation and subsurface properties of about 40-50% of the corresponding error of the unassimilated case. Good forecast skill, better than persistence, is demonstrated for 10-20 days; there is little skill after 30-40 days. Increasing the density of the satellite altimetry data (especially by decreasing the separation distance between tracks) should decrease the nowcast rms error to about 15% and improve the forecast. 89 GF-026 Milly, P. CD. A refinement of the combination equations for evaporation. Surveys in Geophysics 12:145-154 ( 1 99 1 1 . Most combination equations for evaporation rely on a linear expansion of the saturation vapor-pressure curve around the air temperature. Because the temperature at the surface may differ from this temperature by several degrees, and because the saturation vapor-pressure curve is nonlinear, this approximation leads to a certain degree of error in those evaporation equations. It is possible, however, to introduce higher-order polynomial approximations for the saturation vapor-pressure curve and to derive a family of explicit equations for evaporation, having any desired degree of accuracy. Under the linear approximation, the new family of equations for evaporation reduces, in particular cases, to the combination equations of H.L. Penman (Natural evaporation from open water, bare soil and grass. Proc.R.Soc. London Ser. A. 193:120-145, (1948) and of subsequent workers. Comparison of the linear and quadratic approximations leads to a simple approximate expression for the error associated with the linear case. Equations based on the conventional linear approximation consistently underestimate evaporation, sometimes by a substantial amount. GF-027 Milly, P. CD. Some current themes in physical hydrology of the land-atmosphere interface. In Hydrological Interactions Between Atmosphere, Soil and Vegetation. G. Kienitz, P. CD. Milly, M. Th. van Genuchten, D. Rosbjerg and W.J. Shuttleworth (eds.). International Association of Hydrological Sciences, 3-10 (1991). Certain themes arise repeatedly in current literature dealing with the physical hydrology of the interface between the atmosphere and the continents. Papers contributed to the 1991 International Association of Hydrological Sciences Symposium on Hydrological Interactions between Atmosphere, Soil and Vegetation echo these themes, which are discussed in this paper. The land-atmosphere interface is the region where atmosphere, soil, and vegetation have mutual physical contact, and a description of exchanges of matter or energy among these domains must often consider the physical properties and states of the entire system. A difficult family of problems is associated with the reconciliation of the wide range of spatial scales that arise in the course of observational, theoretical, and modeling activities. These scales are determined by some of the physical elements of the interface, by the dynamics of the processes at the interface, and by methods of measurement and computation. Global environmental problems are seen by many hydrologists as a major driving force for development of the science. The challenge for hydrologists will be to respond to this force as scientists rather than problem-solvers. GF-028 Mitchell, J.F.B., S. MANABE, V. Meleshko, and T. Tokioka. Equilibrium climate change - and its implications for the future. In Climate Change, the IPCC Scientific Assessment, J.T. Houghton, G.J. Jenkins, and J.J. Ephraums (eds.). Cambridge University Press, 137-164(1991). No abstract. GF-029 Murnane, R.J., and J.L. Sarmiento. Thorium isotopes, particle cycling models, and inverse calculations of model rate constants. Journal of Geophysical Research 95(C9): 16. 195-16.206 (1990). Generalized models of thorium and particle cycling, data from Station P, and an inversion technique are used to obtain rate estimates of important biological and chemical transformations occurring in the water column. We first verify the inversion technique using an idealized data set generated by a finite difference model, and then apply the inversion technique to data from Station P. With the Station P data, predicted rate constants for adsorption and release of thorium between the dissolved and small particle phases are consistent with the results from other workers. The predicted rate constants for the interaction between small and large particles are smaller than previous estimates. The predicted concentration of large rapidly sinking particles is greater than previous estimates. The predicted concentration of large rapidly sinking particles is greater than the concentration of suspended non-sinking particles, whereas the reverse is usually assumed to be the case. The calculated sinking rate for the large particles is 20 m d '. This sinking rate is an order of magnitude smaller than the large particle sinking rate inferred from sediement trapmass fluxes at two levels in the water column. The reason we predict a high large particle concentration and slow settling velocity has not been uniquely determined. Possible modifications of the current model that could help to reconcile the differences between observations and model predictions include. 1) two classes of rapidly sinking particles or rate constants that change with depth, 2) direct interactions between the large particle and dissolved phases, and 3) incorporation of a continuous distribution of particle size and settling velocity. GF-030 Pan, Y.H., and A.H. OORT. Correlation analyses between sea surface temperature anomalies in the Eastern Equatorial Pacific and the World Ocean. Climate Dynamics 4:191 :205 (1990). Based on data from the Comprehensive Ocean- Atmosphere Data Set (CO ADS), objective analyses of the monthly mean sea surface temperature (SST) were prepared at GFDL for each month of the 1 10-year period 1870-1979. Time series of various indices characterizing 90 the SST anomalies averaged over the eastern equatorial Pacific (EEP), the tropical oceans and the world ocean are presented for monthly, yearly and decadal time-averaging periods. Global correlations maps are given for each decade of the 1870-1979 period. They show the spatial connections between the monthly SST anomalies in the EEP and those in the tropical and world oceans are found to be highly correlated with maximum correlations values of 0.91 at zero lag for the tropical oceans during the 1950-1959 decade and 0.81 for the world ocean during the 1970-1979 decade. Positive correlation values of r > 0.36 persist on average from about 4 months before to about 8 months after the EEP anomalies occur. There is a clear tendency for the tropical and world ocean anomalies to lag behind the EEP anomalies. Comparing different oceans, we find the tendency for the tropical SST anomalies in the Indian and Atlantic Oceans to lag behind those in the EEP region by about 1 and 3 months, respectively. On the interannual time scale the EEP anomalies are also well correlated with those in the other regions, having an average correlation of 0.84 for the tropical oceans and of about 0.7 for the world ocean. GF-031 Peixoto, J., M. de Almeida, A.H. OORT, and A. Tome. Entropy budget of the atmosphere. Journal of Geophysical Research 96(D6):10,981-10,988(1991). The balance equations for the entropy in the atmosphere are presented and discussed. Using observed energy fluxes and atmospheric temperatures, we present estimates of the various terms in the global mean entropy budget. The largest boundary fluxes of entropy are associated with the emission of longwave radiation. The fluxes of entropy associated with turbulent and molecular diffusion are found to be much smaller. On the planetary scale the mean outgoing flux of entropy at the top of the atmosphere is found to be about 22 times larger than the mean incoming flux of entropy through solar radiation. The rates of entropy production and destruction by the various irreversible processes that occur in the atmosphere are also computed. The entropy production terms involved in the release of latent heat and the absorption of solar radiation are, by far, the largest sources of entropy for the atmosphere, whereas the production of entropy associated with the absorption of longwave radiation is an order of magnitude smaller. The destruction is mainly accomplished through cooling by outgoing longwave radiation. The contributions of the sensible heat fluxes and friction are relatively small. Regional contributions to the total entropy generation in the atmosphere are studied by considering an equatorial region bounded by two latitudinal walls at 15-N and 15 *S and a polar region poleward of 70-N. The rates of entropy generation by the various diabatic processes are highest in the equatorial region; part of the generated entropy is exported to higher latitudes. GF-032 Ramaswamy, V., S. Liu, and M.D. SCHWARZKOPF. Preface to JGR-ICRCCM Issue, Journal of Geophysical Research 96(D5):8921-8923(1991). No abstract. GF-033 Ramaswamy, V., and S.M. FREIDENREICH. Solar radiative line-by-line determination of water vapor absorption and water cloud extinction in inhomogeneous atmospheres. Journal of Geophysical Research 96(D5):9133-9157(1991). The complete available spectral features (line-by-line), or LBL) of the water vapor molecule in the solar spectrum and a precise treatment of particular scattering are employed to obtain and analyze the solar radiative fluxes and heating rates in plane-parallel, vertically inhomogeneous model atmospheres containing vapor only, water cloud only, and vapor-plus-cloud present simultaneously. These studies are part of the Intercomparison of Radiation Codes in Climate Models (ICRCCM) project and institute useful benchmark computations against which results from simpler radiation algorithms can be compared, the "exact" solution of the radiative transfer equation for cloudy atmospheres with the cloud in a single model layer consumes an exorbitant amount of computational resources ( - 100 hours on a Cyber 205). Two other techniques that are considerably more economical are also investigated. These techniques, too, are based on the LBL spectral features of the HjO molecule but consist of an approximation in either the vapor optical depth or in the multiple-scattering process. The technique involving the "binning" of the vapor optical depths yields extremely accurate fluxes and heating rates for both the vapor and vapor-plus-cloud cases; in particular, it is a practical alternative for obtaining benchmark solutions to the solar radiative transfer in overcast atmospheres (3.8 hours). In contrast, the multiple-scattering approximation technique does not yield precise results: however, considering computational efficiency (0.5 hours), it offers a rapid means to obtain a first-order approximation of spectrally integrated quantities. The analyses of the alternate techniques suggest their potential use for high spectral resolution sensitivity studies of the radiative effects due to varius types of clouds. GF-034 Randel, W.J., and I.M. HELD. Phase speed spectra of transient eddy fluxes and critical layer absorption. Journal of the Atmospheric Sciences 48(5):688-697 (1991). Tropospheric zonal mean eddy fluxes of heat and momentum, and the divergence of the Eliassen-Palm flux, are decomposed into contributions from different zonal phase speeds. Data analyzed are ECMWF operational global analyses covering 1980-87. Eastward 91 moving medium-scale waves (zonal waves 4-7) dominate the spectra of lower tropospheric heat fluxes in both hemispheres and ail seasons. Upper tropospheric wave flux spectra are similar to the low level spectra in midlatitudes, but shift to slower zonal phase speeds as low latitudes are approached. The cause of this shift is the selective absorption of faster moving components in midlatitudes as the waves propagate meridionally. Latitude-phase speed distributions of eddy fluxes are constructed and compared to the zonal mean wind structure. These results demonstrate that upper tropospheric eddies break and decelerate the zonal mean flow approximately 10* - 20* in latitude away from their critical line (where phase speed equals zonal wind speed). Comparisons are also made with results from the middle stratosphere. GF-035 Saravanan, R. A multiwave model of the quasi-biennial oscillation. Journal of the Atmospheric Sciences 47(21):2465-2474(1990). A simple one-dimensional model of the quasi-biennial oscillation is discussed. Our model is essentially a generalization of the Holton- Lindzen models. We consider a large number of vertically propagating internal waves interacting simultaneously with the mean flow. Effects of both wave damping and critical level absorption are included, but wave-wave interaction is neglected. The effects of momentum advection due to the Hadley circulation are also parameterized. This model is used to study how the mean flow in the equatorial lower stratosphere would respond to forcing by a tropospheric wave spectrum with a significant amount of momentum flux at slow horizontal phase speeds. We find that a "continuous" wave spectrum forces mean flow oscillations in a manner quite similar to a "discrete" two-wave spectrum. But the factors that control the period and amplitude of the oscillations, in the case of a continuous spectrum, seem to be quite different. Our results also suggest that mean rising motion in the tropics may play an important role in determining the vertical structure of the QBO near the tropopause. GF-036 Sarmiento, J.L., G. Thiele, R.M. Key, and W.S. Moore. Oxygen and nitrate new production and remineralization in the North Atlantic subtropical gyre. Journal of Geophysical Research 95(C10):18303-18315(1990). New estimates are obtained of oxygen utilization rates on isopycnal surfaces in the North Atlantic subtropical gyre thermocline based on tritium inventories (2.4-3.5 mol m'2 yr'1) and ^'Ra measurements (8.5 ± 0.8 mol m'2 yr1). Arguments are given for why the tritium inventory oxygen utilization rate estimate may be too low. The ^'Ra results are combined with recent estimates of oxygen utilization within the thermocline (Jenkins, 1987) as well as estimates of oxygen production in the mixed layer (Spitzer and Jenkins, 1989; Musgrave et al., 1988), to suggest a tentative overall oxygen balance for the whole water column. The new production of oxygen in the surface ocean ( — 4.6 ±1.6 mol m'2 yr'1) appears to be lower than the estimated utilization within the thermocline (~8.5 ± 0.8 mol m~2 yr'1), suggesting that there may be a net lateral import of organic matter into the thermocline equivalent to a new production of ~3.9 ± 1.8 mol m'2 yr"'. The nitrogen balance is consistent with these results. An estimate for the total nitrogen remineralization rate in the thermocline is obtained from the oxygen utilization rate by using an -O^N Redfleld ratio of 9.1 ± 0.4 for remineralization (Minster and Boulahdid, 1987), giving a nitrogen remineralization rate of —0.93 ± 0.10 mol m'2 yr1. Subtracting off the estimated lateral export of nitrate of —0.51 ± 0.21 mol m "2 yr"1, which is presumed to be balanced by a lateral import of dissolved organic nitrogen (Rintoul and Wunsch, 1990), gives a nitrate flux into the surface of —0.42 ± 0.23 mol m^yr'1, which is comparable to the estimate of 0.6 ± 0.2 mol m'2 yr"1 obtained by Jenkins (1988) near Bermuda as well as the 100-m particulate nitrogen flux of 0.33 mol m2 yr1 obtained Altabet (1989) near Bermuda. GF-037 SCHWARZKOPF, M.D., and S.B. FELS. The simplified exchange method revisited: An accurate, rapid method for computation of infrared cooling rates and fluxes. Journal of Geophysical Research 96(D5):9075-9096 (1991). The performance and construction of a new algorithm for the calculation of infrared cooling rates and fluxes in terrestrial general circulation models are described in detail. The computational method, which is suitable for use in models of both the troposphere and the middle atmosphere, incorporates effects now known to be important, such as an extended water vapor e-type continuum, careful treatment of water vapor lines, of water-carbon dioxide overlap, and of Voigt line shape. The competing requirements of accuracy and speed are both satisfied by extensive use of a generalization of the simplified exchange approximation of Fels and Schwarzkopf (1975). Cooling rates and fluxes are validated by comparison with benchmark line-by-line calculations on standard atmospheric profiles obtained for the Intercomparison of Radiation Codes Used in Climate Models (ICRCCM). Results indicate that the new algorithm is substantially more accurate than any previously used at the Geophysical Fluid Dynamics Laboratory. GF-038 Tao, X. Atmospheric responses to lower tropospheric forcing in a multi-layer isentropic model. Ph.D. Dissertation, Princeton University, Princeton, NJ. 261 pp. (1990). A multi-layer isentropic model is developed and employed in this thesis to study the importance of Rossby waves in maintaining the atmospheric general circulation. Two kinds of numerical experiment have been designed. In the absence of diabatic heating, the first series of experiments is aimed at studying Rossby wave propagation and breaking in the troposphere and in the stratosphere. The linear response 92 when the forcing amplitude is small is first studied in detail. Then the transition to nonlinear behavior as the forcing amplitude increases is investigated. The greatest mean flow modification first occurs near the critical layer in low-latitudes. The over-reflection of wave activity from critical layer has very important effects on the breakdown of the polar vortex. The results also demonstrate that Rossby waves can penetrate to higher altitude as the forcing amplitude increases. The importance of diabatiac heating is investigated in second type of numerical experiment. The potential vorticity budget is first studied. Then the possibility of vacillation in the stratosphere as a response to steady tropospheric forcing is discussed. In that we found it to be very difficult to break up the polar vortex with steady forcing of realistic amplitude in the time scale of a season. Stratospheric vacillation may be generated by lateral critical line in a much longer time scale. An analytical analysis in a /J-plane channel model is performed to understand the relationship between vertical propagation of Rossby waves and destruction of PV gradient. GF-039 Ting, M., and I.M. HELD. The stationary wave response to a tropical SST anomaly in an idealized GCM. Journal of the Atmospheric Sciences 47(21):2546-2566 (1990). The upper tropospheric stationary wave response to a tropical sea surface temperature (SST) anomaly was examined with an idealized general circulation model (GCM) as well as steady linear and nonlinear models. The control climate of the GCM is zonally symmetric; this symmetric climate is then perturbed by a dipole SST anomaly centered at the equator. Two experiments, with anomaly amplitudes differing by a fact of two have been conducted. The response is very linear in the amplitude of the SST anomaly. A steady, baroclinic model linearized about a zonally symmetric basic state simulates the GCM's stationary wave reasonably well when it is forced by anomalous heating as well as anomalous transients. When decomposing the GCM's flow into parts forced separately by heating and transients, tropical transients are found to play a dissipative role to first approximation, reducing the amplitude of the response to heating by a factor of two. The effects of extratropical transients are relatively weak. A steady nonlinear model is also used to evaluate the importance of transients and confirms the diagnosis based on the linear model. Part of the tropical transients seems to be forced by tropical convection and part by midlatitude disturbances propagating into the tropics. The anomalous extratropical transients include a part related to a shift in the model's storm track and a part related to barotropic instability of the stationary wave, but the effects of both of these changes are relatively weak due to the absence of strong extratropical climatic zonal asymmetries in the model. The dissipative role of transients in this model is contrasted with the positive feedback bound by Held et al. (1989) in a GCM with realistic boundary conditions. The calculations in that paper are repeated, and the direct linear response to thermal forcing is found to be sensitive to the damping included in the model; but the positive feedback from the transients is robust to changes in the linear model. We speculate that a strong asymmetic storm track, with a well- defined barotropic decay region, is needed for the positive feedback to occur. GF-040 TULEYA, R.E. Sensitivity studies of tropical storm Genesis using a numerical model. Monthly Weather Review 119(3):721-733 (1991). This study investigates two cases of the FGGE UJ-B tropical cyclone genesis study of Tuleya (1988) in more detail. These two cases occurred within a week of one another in the tropical North Atlantic in August 1979. One disturbance developed into Hurricane David, the other did not develop past the depression stage. At one point in their evolution the disturbances had quite similar values of low-level vorticity. In the developing case of Hurricane David, the disturbance propagated along in a low-level wave trough with an accompanying high wind maximum. In the nondeveloping case the initial disturbance was also embedded in a wave trough with an associated wind maximum. This low-level wave propagated westward leaving the depression in its wake. The different environmental flow was responsible for the different behavior. Synoptic and budget analyses revealed significant differences in disturbance structure and vorticity and equivalent potential temperature tendencies at the time of approximate equal strength of the two disturbances. The evolution of these two disturbances was quite robust even to reasonable increases to the initial relative humidity. Supplementary experiments of the developing case were performed by altering the sea surface temperature and surface evaporation. It was found that the difference in storm evolution was minor in a case when climatological mean values of sea surface temperatures were specified. The climtological mean values were — 0.5 K lower than the August 1979 mean used in the control simulation. In addition, an experiment without evaporation led to a propagating easterly wave with little development. Furthermore, when the evaporation was specified to a climatological constant value, there was intensification into a weak tropical storm with a rather peculiar structure. Apparently, at least in this case processes other than evaporation-wind feedback led to moderate storm intensification. GF-041 WETHERALD, R.T., S. MANABE, and V. Ramaswamy. A comparative study of the observations of high clouds and simulations by an atmospheric general circulation model. Climate Dynamics 5:135-143 (1991). The importance of clouds in the upper troposphere (cirrus) for the sensitivity of the Earth's climate e.g., requires that these clouds be modeled accurately in general circulation model (GCM) studies of the atmosphere. Bearing in mind the lack of unambiguous quantitative information on the geographical distribution and properties of high clouds, the simulated distribution of upper troposopheric clouds in a spectral GCM is compared with several satellite-derived datasets that pertain to high clouds only, for both winter and summer seasons. In the model, clouds are assumed to occupy an entire gridbox whenever the relative humidity exceeds 99%: otherwise the grid box is assumed 93 to be free of cloud. Despite the simplicity of the cloud prediction scheme, the geographical distribution of the maxima in the model's upper tropospheric cloud cover coincides approximately with the regions of the observed maxima in the high cloud amount and their frequency of occurrence (e.g., intertropical convergence zone and the monsoon areas). These areas exhibit a minimum in the outgoing longwave radiation (OLR;Nimbus-7) and are also coincident with regions of heavy precipitation. The model, with its relatively simple cloud formation scheme, appears to capture the principal large-scale features of the tropical convective processes that are evident in the satellite and precipitation datasets, wherein the intense, upward motion is accompanied by condensation and the spreading of thick upper tropospheric layers of high relative humidity and cloudiness in the vicinity of the tropical rainbelt regions. GF-042 WETHERALD, R.T. and S. MANABE. Hydrologic sensitivity to CO^-induced global warming. Civil Engineering Practice 5(l):33-36 (1990). No abstract. GF-043 Xue, H. Numerical studies of Gulf Stream meanders in the South Atlantic Bight. Ph.D. Dissertation, Princeton University, Princeton, NJ. 188 pp. (1991). Gulf Stream meanders in the South Atlantic Bight have been numerically studied by means of stability analyses and numerical simulations. Stability analyses are carried out by solving eigenvalue problems obtained from the linearized primitive equations. The most unstable wave found in the model has a wavelength of 215 km and a phase speed of 39.7 kn/day for the cross-section upstream of the Charleston Bump, and it has a wavelength of 225 km and a phase speed of 33.0 km/day for the cross-section downstream of the Charleston Bump. At each cross-section, the flat bottom case is provided to study topographic effects. Baroclinic instability is reduced due to the topography, especially in the area where the bottom slope exceeds the slope of deep isopycnals. Barotropic instability is hardly affected by the topography. The growth rate of the most unstable wave reduces by 30 to 50 percent, and the maximum growth rate shifts towards smaller wavenumbers and higher phase speeds after incorporating the topography. Numerical simulations of the Gulf Stream in the South Atlantic Bight are carried out by using a fully nonlinear, three-dimensional model with rather simplified geometry. The continental slope acts as a stabilizing factor. Although the growth rate decreases by only 30 percent, this small amount of reduction is crucial to the development of substantial meanders. Perturbations grow rapidly in amplitude and form frontal eddies in the flat bottom case. However, after incorporating the topography, all perturbations move out of the domain before developing into finite amplitude meanders. Meanders can be produced in the model with the topography by perturbing the temperature field at the southern boundary. The presence of the bump provides favorable conditions to realise the mean potential energy, but it is not able to excite large meanders upstream and downstream of the bump. When both the oscillating southern boundary condition and the bump are included, the resultant meanders are closest to those observed . The averaged wavelength is about 230 km, and the phase speeds are about 40 and 35 km/day upstream and downstream of the bump, respectively. GF-044 Zhu, X., and D.F. Strobel. On the role of vibration-vibration transitions in radiative cooling of the COj 15 pm band around the mesopause. Journal of Geophysical Research 95(D4):3571-3577(1990). We determine the importance of V-V transitions in the radiative cooling by the COj 15 nm band near the mesopause where the maximum error in cooling rate by two-level model is expected to occur. It is shown that the effect of including V-V transitions is to locally smooth the source functions for different sub-bands toward a single mean value. This effect allows the changes in cooling rate for each sub- band to partially cancel each other, so the total change in cooling rate for the whole band is not very significant. It is found that the maximum error in cooling rate around the mesopause is ~0.5°K day "'. We have also examined errors in the cooling rate of the C02 15 fun band for an equivalent two-level model suggested by Zhu (1990). The maximum error in cooling rate for the equivalent two-level model is — 1 .3°K day l around the summer mesopause. Present calculations confirm that the equivalent two-level model can be used in GCM's to calculate the C02 15-^m band cooling rate. GF-045 Zhu, X. Spectral parameters in band models with distributed line intensity. Journal of Quantitative Spectroscopy Radiative Transfer 45(I):33-46 (1991). In this paper, a concept of intermediate limits is introduced. Using intermediate limits, together with the traditional weak and strong limits, all parameters in a band model with distributed function can be determined systematically. The method is applied to two band models with S"1"* tailed distributions developed by Zhu in 1989. The important band quantity leading to an intermediate limit for H20, C02, and 0„ and the traditional quantities leading to the weak and strong limits, are calculated in a form similar to that in Houghton's textbook according to the latest HITRAN database. 94 GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY GL-001 ASSEL, R.A. An ice-cover climatology for Lake Erie and Lake Superior for the winter seasons 1897-1898 to 1982-1983. International Journal of Climatology 10:731-748 (1990). Observations of mid-lake Great Lakes ice cover are sparse prior to the decade of the 1960s. In an effort to provide an historical perspective of mid-lake ice cover back to the turn of the century, daily average ice cover for Lakes Erie and Superior over 86 winters (1897-98 to 1982-83) was reconstructed using empirical-statistical ice cover models developed in an earlier study. Long-term average maximal monthly ice cover occurs in February and is 68 percent for Lake Erie and 40 percent for Lake Superior. Mid-lake ice formation occurs about 1 month earlier on both lakes during severe winters. Average maximal monthly ice cover during severe and during mild winters is 95 percent and 14 percent for Lake Erie, 87 percent and 17 percent for Lake Superior. Severe winters are associated with lower 700-mbar heights over the eastern USA com- pared with mild ice-cover winters. Analysis of total winter ice cover indicates three ice cover regimes: (i) a high ice-cover regime from the late 1980s to early 1920s; (ii) a low ice-cover regime from the early 1920s to late 1950s; and (iii) a high ice-cover regime from the late 1950s to the early 1980s. Ice-cover climatologies developed during the 1960s and 1970s are not representative of ice covers in the low ice-cover regime of the 1920s to late 1950s. Spectral analysis of the reconstructed total winter ice cover suggests interannual variations in ice cycles that corre- spond with the 2-3 year interannual variation in atmospheric variables known as the quasi-biennial oscillation. GL-002 ASSEL, R.A. Implications of C02 global warming on Great Lakes ice cover. Climatic Change 18:377-395 (1991). Statistical ice cover models were used to project daily mean basin ice cover and annual ice cover duration for Lakes Superior and Erie. Models were applied to a 1951-80 base period and to three 30-year steady double carbon dioxide (2xCOz) scenarios produced by the Geophysi- cal Fluid Dynamics Laboratory (GFDL), the Goddard Institute of Space Studies (GISS), and the Oregon Slate University (OSU) general circu- lation models. Ice cover estimates were made for the West, Central, and East basins of Lake Erie and for the West, East, and Whitcfish Bay basins of Lake Superior. Average ice cover duration for the 195 1-80 base period ranged from 13 to 16 weeks for individual lake basins. Re- ductions in average ice cover duration under the three 2xCO, scenarios for individual lake basins ranged from 5 to 1 2 weeks for the OSU sce- nario, 8 to 13 weeks for the GISS scenario, and 1 1 to 13 weeks for GFDL scenario. Winter without ice formation become common for Lake Superior under the GFDL scenario and under all three 2xC02 scenarios for the Central and East Basins of Lake Erie. During an average 2xC02 winter, ice cover would be limited to the shallow areas of Lakes Erie and Superior. Because of uncertainties in the ice cover models, the results given here represent only a first approximation and are likely to represent an upper limit of the extent and duration of ice cover under the cli- mate change projected by the three 2xC02 scenarios. Notwithstanding these limitations, ice cover projected by the 2xC02 scenarios provides a preliminary assessment of the potential sensitivity of the Great Lakes ice cover to global warming. Potential environmental and socioeconomic imparts of a 2xC02 warming include year-round navigation, change in abundance of some fish species in the Great Lakes, discontinuation or reduction of winter recreational activities, and an increase in winter lake evaporation. GL-003 ASSEL, R.A., and D.C. NORTON. A comparison of Great Lakes winter severity and ice cover — winter 1990 vs. the historical record. Proceedings, 1990 Annual Meeting of the Eastern Snow Conference, Bangor, ME, June 7-8, 1990. 143-154 (1990). The large temperature anomaly reversal from December 1989 to January 1990 is described along with its associated impact on early winter snowfall and ice formation. Winter temperature severity is evaluated in terms of magnitude and date of occurrence of the annual maximal freezing degree-day accumulations at several locations on the perimeter of the Great lakes. Winter severity from the turn of the century to the early 1980s is compared with the 1990 winter severity. The extent and date of occurrence of maximal ice cover for the 1990 winter is placed in an historical perspective by comparing it with the annual maximal ice covers of the preceding three decades. GL-004 ASSEL, R.A., and J.M. RATKOS. Animation of the normal ice cycle of the Laurentian Great Lakes of North America. Preprints, Sev- enth International Conference on Interactive Information and Processing Systems for Meteorology, Hydrology, and Oceanography, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, MA, 331-335 (1991). No abstract. GL-005 Baker, J.E., S.J. Eisenreich, and B.J. EADIE. Sediment trap fluxes and benthic recycling of organic carbon, polycyclic aromatic hydrocar- bons, and polychlorobiphenyl congeners in Lake Superior. Environmental Science and Technology 25(3):500-509 (1991). Sediment trap fluxes of solids, organic carbon, polycyclic aromatic hydrocarbons (PAHs), and polychlorinatcd biphenyl (PCBs) were mea- sured in Lake Superior in 1984 and 1985. Mass fluxes from surface waters ranged from 0.14 to 1.1 g/m2»day and increased near the lake floor due to resuspension of surficial sediment and horizontal transport in the benthic nepheloid layer. Organic matter fluxes from surface waters 95 ranged from 60 to 90 mg of C/m2»day, with -5% of organic carbon settling from surface waters accumulating in bottom sediments. Concentra- tions of PCBs and PAHs are enriched 10-100 times on settling particles relative to those on suspended particles. Resultant settling fluxes are 10-100 times greater for several PCB and PAH compounds than net accumulation rates in bottom sediments, indicating the effective and rapid recycling in the benthic region. Biological packaging of organic pollutants into rapidly settling particles is an efficient pathway for the trans- port of contaminants from surface waters to benthic regions of large lakes. GL-006 BEETON, A.M. Limnology of the Nam Ngum Reservoir, Laos. Verhandlungen -Internationale Vereinigung Fur Theoretische und Angewandte Limnologie 24:1436-1444 (19911 No abstract. GL-007 BEETON, A.M. Virtual elimination of toxic substances in the changing Great Lakes. Proceedings, 1990 Annual Meeting of the Universi- ties Council on Water Resources, West Point, NY, August 2, 1990 (1991). No abstract. GL-008 BEETON, A.M., and J.E. Gannon. Effect of environment on reproduction and growth of Mysis relicta. American Fisheries Society Sym- posium 9:1 14-148 (1991). Published and unpublished data were examined to determine whether the time to first reproduction, brood size, and growth rate of Mysis relicta are related to environmental conditions. Time to first reproduction ranged from 1 year in eutrophic lakes to 4 years in an ultraoligotrophic lake. Mysids in nutrient-rich lakes may have 45 eggs per brood, whereas those in less productive lakes had 10-12 eggs per brood. Growth rates ranged from 1 .0 to 1.5 mm/month in productive lakes to only 0.2 mm/month in ultraoligotrophic Lake Tahoe. Some dif- ferences in reproduction and growth rate consistent with the above observations occurred between areas of Lakes Tahoe and Michigan that dif- fered in trophic conditions. GL-009 BRATKOVICH, A.W. NOAA ship requirements for fisheries oceanography. In NOAA's Ocean Fleet Modernization Study. Phase 1: Mission Requirements. National Oceanic and Atmospheric Administration, pp. A69-A73 (1990). No abstract. GL-010 CONLEY, D.J., and D. SCAVIA. Size structure of particulate biogenic silica in Lake Michigan. Journal of Great Lakes Research 17(l):18-24 (1991). Recent data suggest that chemical estimates of biogenic silica in the Laurentian Great Lakes include large fractions of non-living frag- mented diatoms. Therefore, measurements of particulate biogenic silica (BSi) in different size classes (0.2-0.4 (im, 0.4-10 (im, 10-20 (im, and >20 |im) were made from April through July 1987 in southeastern Lake Michigan to assess the importance of diatom fragments to chemical es- timates of BSi. During the spring diatom bloom, the period of maximum BSi concentration, the greatest percentage of BSi (86%) was found in the microplankton size fraction (>10 (im) associated with living diatoms. By contrast, following thermal stratification, when dissolved silica was depleted from epilimnetic waters, particles < 10 (im in size dominated and averaged 52% of total BSi. This fraction contained mostly frag- mented diatom frustules. Our estimate of non-living diatoms is consistent with previous studies showing that, following the spring diatom bloom, 40% to 60% of total diatom abundance is non-living. Seasonal decreases in epilimnetic BSi, declining from 1 1.3 (imol L ' in late April to an average of 1 .96 (imol L ' during the stratified period, were due primarily to loss of the largest size fraction (>20 |im) which decreased from 76% of total BSi in April to 36% in July. BSi < 10 (im varied by less than a factor of two throughout the study period, averaging 3.23 + 2.79 (imol L '. Particles 0.2-0.4 (lm averaged 0.277 + 0.178 (imol L '. These particles are probably produced through frustule dissolution, settle slowly, and may lead to enhanced BSi recycling rates. GL-011 Coordinating Committing on the Great Lakes Basic Hydraulic and Hydrologic Data. Great Lakes hydromet database directory. NOAA TM ERL GLERL-74, (PB91-201327/GAR), 49 pp. (1991). No abstract. 96 GL-012 CROLEY, T.E., II. Laurentian Great Lakes double C02 climate change hydrological impacts. Qimatic Change 17:27-47 (1990). The Great Lakes Environmental Research Laboratory has developed conceptual daily models for simulating moisture storages in and run- off from the 121 watersheds draining into the Laurentian Great I^akes, over-lake precipitation into each lake, and the heat storages in and evaporation from each lake. We combine these components as net basin supplies for each lake to consider climate change scenarios developed from atmospheric general circulation models (GCMs). Recent scenarios of a doubling of atmospheric COr available from the Goddard Insti- tute for Space Sciences, the Geophysical Fluid Dynamics Laboratory, and Oregon State University are considered by making changes in his- torical meteorological data similar to the changes observed in the GCMs, observing the impact of the changed data in the model outputs to model results using unchanged data, representing comparison to an unchanged atmosphere. This study indicates a 23 to 51% reduction in net basin supplies to all the Great Lakes; there is significant variation in the components of these supplies among the three GCMs. The basins vari- ous moisture storages become dryer and the lakes are warmer with associated hydrological impacts. GL-013 CROLEY, T.E., II. Use of general circulation model simulations in regional hydrological climate change impact studies. Proceedings, A Symposium on Climate Scenarios, University of Waterloo, Waterloo, Ontario, Canada, June 12, 1991. 34-48 (1991). No abstract. GL-014 CROLEY, T.E., U, and S.V. Ferronsky. Areal averaging of point meteorological measurements (text in Russian, computer program in En- glish). In Climate Change Impacts on the Hydrology of the Caspian Sea. Issue 2. G.N. Golubev (ed.). Academy of Sciences of the USSR Soviet Geophysical Committee, Moscow, 130 pp. (1990). No abstract. GL-015 CROLEY, T.E., II, and S.V. Ferronsky. Building digital maps of the hydrological basins (text in Russian, computer program in English). In Climate Change Impacts on the Hydrology of the Caspian Sea. Issue 1. G.N. Golubev (ed.). Academy of Sciences of the USSR Soviet Geophysical Committee, Moscow, 43 pp. (1990). No abstract. GL-016 CROLEY, T.E., II, and H.C. HARTMANN. GLERL's near real time hydrological outlook package. Proceedings, Great Lakes Water Level Forecasting and Statistics Symposium, Windsor, Ontario, Canada, May 17-18, 1990. Great Lakes Commission, Ann Arbor, MI, 63- 72 (1990). The Great Lakes Environmental Research Laboratory developed a semiautomatic software package for making deterministic or probabilis- tic outlooks of basin moisture storage conditions, basin runoff, lake heat storage, lake evaporation and other heat fluxes, net lake supplies, and lake levels six or more full months into the future for large lakes. We designed the package especially for use on small computers with a stan- dard FORTRAN-77 compiler, 5-15 megabytes of disk storage (per application), and a minimum of processor and memory resources. The package combines our Large Basin Runoff Model applications on each of the subbasins about a lake to represent the entire basin's current moisture storage and our lake evaporation model applications on each of the Great Lakes to represent each lake's current heat storage. Our near-real-time data reduction system uses new algorithms to efficiently determine daily area] averages of meteorologic variables over each of the subbasins. We select historic meteorologic sequences, representing anticipated meteorology, based on the National Weather Service monthly and seasonal forecasts of precipitation and air temperature probabilities, for use with the runoff and evaporation models to generate our near real-time outlooks. The package construction is presented and the use of its modules are detailed. GL-017 DERECKI, J.A., and F.H. QUTNN. Comparison of measured and simulated flows during the 15 December 1987 Detroit River flow rever- sal. Journal of Great Lakes Research 16(3):426-435 (1990). Flow reversals in the Detroit River are unique hydraulic phenomena which disturb the norma] flow patterns and which may cause high con- centrations of water bom pollutants by temporarily blocking their downstream transport and dilution. Until recently, flow reversals in the river have been implied from water level relationships and unsteady numerical flow models, but not directly measured. An acoustic Doppler current profiler deployed on the river bottom at Ft. Wayne, in Detroit, has provided the first opportunity to directly measure a flow reversal, which oc- curred for about 3 hours on 15 December 1987. The meter provided continuous measurements of the vertical velocity distribution for approxi- mately 1-m depth segments in the overhead water column at quarter-hour intervals. These measurements provided an ideal data set to analyze river dynamics associated with flow reversals and to evaluate the importance of major factors necessary for the occurrence of flow reversals in the river. It was found that reasonably accurate simulation of flow reversals with the unsteady flow models require the inclusion of surface 07 wind shear and the use of small time increments that are much shorter than the standard hourly water level data. Model simulation with spe- cially obtained 5 and 15 minute water level and wind data produced generally similar model flows that are reasonably close to the measured values. Because short-period (15 minute or less) wind and water level data are not readily available, river flow reversals simulated using hourly data may be significantly underestimated. GL-018 Dickey, T, J. Marra, T. Granata, C. I^angdon, M. Hamilton, J. Wiggert, D. Siegel, and A.W. BRATKOVICI1. Concurrent high resolution bio-optical and physical time series observations in the Sargasso Sea during the spring of 1987. Journal of Geophysical Research 96(C6):9643-9663(1991). The evolution of bio-optical and physical properties of the upper layer of the open ocean has been examined at time scales from a few min- utes to several months using recently developed multi-variable moored systems (MVMS). Concurrent, eolocated time series measurements of horizontal currents, temperature, photosynthetically available radiation, transmission of a beam of collimated light (660 ran), stimulated chloro- phyll fluorescence, and dissolved oxygen concentration were made. The systems were located at eight depths in the upper 160 m of the Sar- gasso Sea 34°N, 70°W) and were deployed three times for a total of 9 months in 1987. The first deployment data presented here show consider- ably more variability than those of the latter two deployments because of the dynamic springtime shoaling of the mixed layer and the accompa- nying phytoplankton bloom and more mesoscale variability associated with cold core rings and warm outbreak waters associated with the Gulf Stream. These data are used to demonstrate the utility of the MVMS and indicate the importance of high-frequency, long-term sampling of bio-optical and physical variables of the upper ocean for understanding and modeling dynamical changes in bio-optical properties, primary producation, and carbon fluxes of the upper ocean on time scales ranging from minutes to seasons to decades. Some phenomena observed with the systems include (1) diurnal variations in bio-optical properties, (2) springtime stratification and rapid (~2 days and less) episodic changes in the beam attenuation coefficient and in situ chlorophyll fluorescence, and (3) advective episodes with warm outbreaks of Gulf Stream waters and cold core Gulf Stream rings in the vicinity of the mooring. GL-019 Donelan, M., M. Skafcl, H. Grabcr, P.C. LIU, D.J. SCHWAB, and S. Venkatesh. On the growth rate of wind -generated waves. National Water Research Institute Publication 91-117, Burlington, Ontario, Canada, 32 pp. (1990). A new approach to fetch-limited wave studies is taken in this paper. Using data from five towers arranged along a line from the eastern shore of Lake St. Clair, the differential growth between towers is explored as a function of local wave age. It is argued that this method avoids the usual fetch-limited pitfall of inhomogeneity over long fetches and, in particular, the changes in wind speed downfetch of an abrupt rough- ness change. It is found that the growth rate decreases uniformly downfetch as the waves approach full development This differential method leads to a smooth transition from rapidly growing short fetch waves to the asymptotic invariant state of full development. GL-020 EADIE, B J., J.A. ROB BINS, W.R. FAUST, and P.F. LANDRUM. Polycyclic aromatic hydrocarbons in sediments and pore waters of the lower Great Lakes: Reconstruction of a regional benzo(a)pyrene source function. In Organic Substances and Sediments in Water Vol- ume 2. Processes and Analytical. R. Baker (ed.). Lewis Publishers, Chelsea, MI, 171-189 (1991). No abstract. GL-021 Edgington, D.N., J. Val Klump, J.A. ROBBINS, Y.S. Kusner, V.D. Pampura, and I.V. Sandimirov. Sedimentation rates, residence times, and radionuclide inventories in Lake Baikal from 137Cs and 2,0Pb in sediment cores. Nature 350:601-604 (1991). Radionuclides in lake sediments may act as indicators of the sedimentation rate of particles on which they are adsorbed; these rates in turn provide a direct indication of the residence times of particles in the water column. The radionuclide 137Cs is anthropogenic (an atomic -bomb product), so that its concentration in sediments also reveals the input history of this species and thus a record of atmospheric contamination by this nuclide in the lake's watershed. Here we report measurements of ,37Cs and the natural radionuclide J10Pb in cores from several stations throughout the three basins of Lake Baikal. The results confirm earlier indirect estimates of the mean sedimentation rate, and show that the ef- fective settling rate of these radionuclides is the same as that in the Great Lakes; the longer residence times for Lake Baikal are therefore sim- ply a consequence of its greater depth. As well as allowing estimates of fluxes at the sediment-water interface, our results provide information on the timing of paleolimnological events, on the existence of different depositional zones throughout the lake, on the long-term (decadal) dif- fusion of nuclides in sediments, and for the development of mass balance models for sediments and contaminants. GL-022 Evans, M.S., M.A. QUIGLEY, and J.A. Wojcik. Comparative ecology of Pontoporeia hoyi populations in southern Lake Michigan: the profundal region versus the slope and shelf regions. Journal of Great Lakes Research 16(l):67-40 (1990). This study investigates Pontoporeia hoyi ecology in the profundal region (approximated by a 97-m station) of southern Lake Michigan and 98 compares these results with previous investigations conducted in the slope and shelf regions of the lake. Pontoporcia typically attains its maxi- mum abundance in the slope region, suggesting that this region of the lake is the most favorable for amphipod growth and survival. Profundal and slope P. hovi exhibited little seasonal variation in mean size while shelf-region populations exhibited strong seasonal variation in mean size. Deepwater sculpins, a major predator on profundal populations of P. hovi. selectively consumed the largest amphipods: mean size con- sumed was 6-7 mm. The relative sparsily of larger (> 5 mm) P. hovi in the profundal, slope, and shelf regions of the lake may arise from in- tense size-selective fish predation on this size class of amphipods. Gut content studies revealed that profundal P. hovi populations feed inter- mittently. Such feeding behavior was subtly different from that previously observed for slope P. hovi populations: profundal populations feed more continuously but less intensively than slope populations. Regional differences in feeding behavior may be related to differences in food regime and to predation avoidance strategies. Pontoporeia hoyi apparently is capable of inhabiting a broad range of depth regimes by modify- ing its physiology (reproductive cycles, generation time) and behavior (feeding, motility) to adjust to spatial variations in temperature, food level, and predation. GL-023 FAHNENSTTEL, G.L, H.J. CARRICK, and R. Iturriaga. Physiological characteristics and food-web dynamics of Svnechococcus in Lakes Huron and Michigan. Limnology and Oceanography 36(2):219-234 (1991). Single Svnechococcus cells accounted for an average of 10% (range 1-26%) of surface mixed-layer primary production in Lakes Huron and Michigan in 1986-1988. Maximal photosynthetic rates (P ) were relatively low (range = 1.9-6.0 fg C cell ' h ') and no significant pho- toinhibition was found at irradiances as high as 3.0 Einst m 2 h '. Svnechococcus growth rates estimated by four techniques (ampicillin, 14C up- take, dilution, and small inocula) ranged from 0.1 to 0.9 d ' with a mean of 0.37. Although substantial variability was noted among techniques on any one date, on average all estimates were in reasonable agreement with the exception of the dilution estimates which were significantly lower (P < 0.01). Three techniques for estimating grazing loss rates (ampicillin, dilution, and ,4C-labeling of Svnechococcus) provided similar estimates ranging from 0.1 to 0.7 d '. On specific dates, grazing loss rates were 33-120% of growth rates, suggesting that grazing was the major loss for Svnechococcus populations in these lakes. Most of the grazing loss (68%) was attributable to small (4-10 u.m), heterotrophic flagel- lates and ciliates. Crustaceans and rotifers accounted for only a small percentage of total grazing loss (5-21%) even when Daphnia accounted for 40% of crustacean biomass. GL-024 FAHNENSTTEL, G.L., C.L. Schelske, and M.J. McCORMTCK. Phytoplankton photosynthesis and biomass in Lake Superior: Effects of nutrient enrichment. Vcrhandlugen Internationale Vereinigung Fur Theoretische und Angewandte Limnologie 24:371-377 (1990). No abstract. GL-025 FONTAINE, T.D., ITJ, and D.J. Stewart. Trophic dynamics and ecosystem integrity in the Great Lakes: Past, present, and possibilities. In An Ecosystem Approach to the Integrity of the Great I.akes in Turbulent Times. C.J. Edwards and H.A. Regier (eds.). Great Lakes Fish- ery Commission Special Publication 90-4, 153-167 (1990). The Great Lakes are perhaps unique among large lakes of the world in the degree to which fish population dynamics and water quality re- sources can be influenced by management at the bottom of the food web. Non -management factors known to affect fish quality and quantity and water quality, include toxic contaminants, short-term weather events and long-term climatic changes, exotic species invasions, and evolu- tionary changes of existing species. Because fisheries-based revenues to the Great Lakes region are presently estimated at $2-4 billion per year, it would seem prudent to determine the extent to which management and nonmanagement factors influence fish quality and quantity as well as water quality. Here we present a comprehensive, yet preliminary, conceptual and mathematical modeling approach that describes causal relationships among fish food web, nutrient cycling, and contaminant processes in the southern basin of Lake Michigan. Our approach identifies weaknesses in the data base that are important to the predictive usefulness of such a model. We suggest that our comprehensive mod- eling approach will be useful in transforming some surprises into expected events. For instance, the model predicts that contaminant concentra- tions in salmonines will decrease by nearly 20% if Bythotrephes. an exotic carnivorous zooplankton, successfully establishes itself in Lake Michigan. GL-026 GARDNER, W.S., and P.A. St. John. High-performance liquid chromatographic method to determine ammonium ion and primary amines inseawater. Analytical Chemistry 63:537-540 (1991). No abstract. GL-027 GARDNER, W.S., S.P. Seitzinger, and J.M. MALCZYK. The effects of sea salts on the forms of nitrogen released from estuarine and freshwater sediments: Does ion pairing affect ammonium flux? Estuaries 14(2):157-166 (1991). 99 In sediments with oxidized surface layers, the percentage of mineralized nitrogen that is nitrified/denitrified, compared with that released directly as ammonium, appears to be affected by the presence of sea salts. In estuarine systems, a significant portion of the nitrogen is released as ammonium, whereas in fresh water systems, most of the mineralized nitrogen is often released from the sediments as nitrogen gas. We hy- pothesized that this discrepancy is caused by differential competition between physical diffusion and nilrification/denitrification in the two sys- tems. The vertical migration (by Fickian diffusion) of ammonium out of the oxic layer may be hindered by cation exchange (or sorption) inter- actions with sediment particles to a greater extent in fresh water than in estuarine systems. The resulting relatively long residence time, and po- tentially high levels of particle-bound ammonium in the fresh water sediments, would favor nitrification as the major ammonium removal pro- cess. By contrast, ion pair formation of ammonium with seawater anions and blockage of sediment cation exchange sites with seawater cations may allow a sizable fraction of the ammonium to diffuse out of estuarine sediments before it is nitrified. A salt effect, consistent with this hy- pothesis, has been demonstrated in experimental systems by changing the ionic composition of water flowing above intact cores of freshwater and estuarine sediments. Steady-state ammonium release from Lake Michigan sediments was substantially enhanced in the presence of 30% seawater over that in the presence of lake water alone. Likewise, steady-state ammonium release, from Ochlockonee River and Bay sediments (Florida) and from Toms River and Bamegat Bay sediments (New Jersey), was usually higher in the presence of diluted synthetic seawater than it was in the presence of fresh water. GL-028 GARDNER, W.S., L.R. HERCIIR, P.A. St. John, and S.P. Seitzinger. High performance liquid chromatographic determination of 15NH4:[UNH4 + 15NH4] ion ratios in seawater for isotope dilution experiments. Analytical Chemistry 63:1838-1843 (1991). A liquid chromatographic method with fluorometric detection, after postcolumn labeling with o-phthalaldehyde/2-mercaptoethanol re- agent, was developed to directly quantify 15NH4:["NH4 + "NHJ ion ratios in aqueous samples that had been enriched with 15NH4 for isotope di- lution experiments. Cation-exchange chromatography, with a sodium borate buffer mobile phase, was selected as the separation mode because the two isotopes have slightly different constants in the equilibrium reaction between ammonium ion and ammonia. When the two forms of ammonium were passed separately through a high-performance cation-exchange column under precisely controlled chromatographic condi- tions, the retention time (RT) of 15NH4 was 1.012 times the RT of l4NH4. The two isotopic forms of ammonium ion were not resolved into separate peaks when they were injected together, but the retention time of the combined peak, as defined by an integrator, increased with in- creasing percentages of 15NH4 in the mixture. The relationship of RT shift vs percentage of 15NH4 relative to total ammonium followed a sig- moid-shaped curve with the maximum RT shifts per change in isotopic composition occurring between 25 and 75% ,5NII4. Using a calibration curve based on this relationship and a solution of separately injected 14NH4 in mobile-phase buffer as an "internal standard," we were able to di- rectly determine the concentrations and ratios of the two isotopes in enriched seawater. GL-029 GOTTLIEB, E.S., J.H. SAYLOR, and G.S. MILLER. Currents and water temperatures observed in Green Bay, Lake Michigan. Part I: Winter 1988-1989, Part II: Summer 1989. NOAA TM ERLGLERL-73 (PB91-129072/XAB),90pp. (1990). To help monitor the transport of water within Green Bay and the exchange of waters between the bay and Lake Michigan, current meter moorings were deployed in the bay and in the passages separating the bay and Lake Michigan, from September 1988 to April 1989 (Part I: Winter) and again from May to September 1989 (Part U: Summer). The winter deployment involved 8 current meter moorings, whereas sum- mer included 21 moorings, 3 thermistor chains, and 7 LORAN-C tracked drifters (July only). Each mooring held two or three current meters, usually placed at 12 and 20 m depth and 5 m above the bottom. To aid in understanding the winter data, maps of ice concentration and thickness are included in Part I. Although currents under the ice are surprisingly energetic at the lunar semi-diurnal tide and Lake Michigan surface seiche periods, monthly-averaged currents reveal a very weak and poorly defined mean circulation pattern in the bay. Despite partial ice cover, bidaily-averaged currents are strong, burstlike, and mostly outward through Death's Door Passage, and weaker, steadily inward, and slightly warmer through Rock Island Passage. Monthly-averaged summer currents (Part IT) show a somewhat anucyclonic circulation pattern in the southern half of the bay, and a persis- tent inflow below 20 m depth through all four major passages. Above 20 m however, outflow is notable only through Death's Door passage. Comparison of bidaily-averaged currents and observed wind patterns indicates that north to northeast winds create a single cyclonic circulation cell in the bay, and south to southwest winds create a two-celled pattern that has an anticyclonic cell in the south half of the bay and a cyclonic cell in the north. Low-pass-filtered currents and temperatures during July and August reveal a strong, persistent, well-defined, 8-day-long os- cillation associated with seiching of the thermocline in Green Bay. Thermistor chain data indicate an amplitude of about 6 to 10 m for the in- ternal seiche. GL-030 GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY. Annua] Report for the Great Lakes Environmental Research Labo- ratory - FY 1990. Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 60 pp. (1991 ). No abstract. GL-031 HARTMANN, H.C. Climate change impacts on Laurentian Great Lakes levels. Climatic Change 17:49-67 (1990). I Of) Scenarios of water supplies reflecting C02-induced climatic change are used to determine potential impacts on levels of the Laurcniian Great Lakes and likely water management policy implications. The water supplies are based on conceptual models that link climate change scenarios from general circulation models to estimates of basin runoff, overlake precipitation, and lake evaporation. The water supply compo- nents are used in conjunction with operational regulation plans and hydraulic routing models of outlet and connecting channel flows to estimate water levels on Lakes Superior, Michigan, Huron, St. Clair, Erie, and Ontario. Three steady-state climate change scenarios, corresponding to modeling a doubling of atmospheric C02, are compared to a steady-state simulation obtained with historical data representing an unchanged at- mosphere. One transient climate change scenario, representing a modeled transition from present conditions to doubled C02 concentrations, is compared to a transient simulation with historical data. The environmental, socioeconomic, and policy implications of the climate change ef- fects modeled herein suggest that new paradigms in water management will be required to address the prospective increased allocation con- flicts between users of the Great Lakes. GL-032 HARTMANN, H.C., and T.E. CROLEY, II. An evaluation of GLERL's hydrological outlook package. Proceedings, Great Lakes Water Level Forecasting and Statistics Symposium, Windsor, Ontario, Canada, May 17-18, 1990. Great Lakes Commission, Ann Arbor, MI, 177-194 (1990). The Great Lakes Environmental Research Laboratory developed a series of physically -based conceptual models for making deterministic or probabilistic outlooks of large lake hydrology, including net basin supplies and lake levels, which consider existing basin moisture and lake heat storages and National Weather Service forecast meteorology. The performance of GLF.RL's Hydrological Outlook Package, used in a simulated operational application, is evaluated for the period from August 1982 through December 1988. Two subperiods, which have extreme and extremely different net basin supplies, are evaluated as well. Considering all three evaluation periods, deterministic outlooks of net basin supplies are best on Lake Superior. Deterministic outlooks, however, have inherent limitations, since they provide only a single forecast time series. Alternatively, probabilistic outlooks explicitly communicate the uncertainty and potential diversity of future hydrometeorologic condi- tions. Our probabilistic net basin supply outlooks are most informative for 1 -month forecasts for Lakes Michigan, Superior, and St. Clair. Im- provements in forecasting depend on better National Weather Service monthly and seasonal weather outlooks, and better selection of historic meteorologic sequences to use as forecast scenarios. GL-033 HERCHE, LR., and H.C. HARTMANN. Estimation of Great Lakes water level statistics: Conditioning via "the bootstrap." Proceedings, Great Lakes Water Level Forecasting and Statistics Symposium, Windsor, Ontario, Canada, May 17-18, 1990. Great Lakes Commission, Ann Arbor, MI, 291-309 (1990). Reliable lake level frequency distributions are a critical component of any comprehensive strategy for coping with Great Lakes water level fluctuations. However, statistical techniques commonly used on riverine systems are inappropriate for large lake systems, due to the levels' long-term persistence and dependence on the prevailing climatic regime. To illustrate an alternative methodology, we present a series of resampling analyses modeled after well -known bootstrap techniques, applied to 1 30 years of monthly Lake Erie water level records. The analyses show that lake level exceedance probabilities should be conditioned on 1) length of the planning horizon, 2) starting month of plan- ning horizon, 3) initial lake level, and 4) climatic regime. Our methodology can be extended to additionally consider storm and wind effects on levels, to incorporate levels data available for discontinuous periods prior to 1860, and to develop other types of lake level statistics useful to decision makers, such as duration and time-to-exceedance probabilities. GL-034 JOHENGEN, T.H., A.M. BEETON, and D.W. Rice. Evaluating the effectiveness of best management practices to reduce agricultural nonpoint source pollution. Lake and Reservoir Management 5(1 ):63-70 (1989). The Saline VaUey project is one of 20 national projects sponsored by the U.S. Department of Agriculture (USDA) under the Rural Clean Water Program (RCWP) to evaluate methods of controlling agricultural non-point source pollution. The goals of this project were (1 ) to evalu- ate whether a voluntary approach using cost-share incentives would produce adequate participation by local farmers and (2) to reduce phospho- rus loads from the area by 40 percent. Water quality has been monitored since 1981 using weekly grab samples and flow measurements. Trends in empirical relationships between concentration and discharge at three sampling stations were used to examine the effectiveness of best management practices (BMP). These relationships were highly variable among the sub-basins and years, and did not appear to correlate with areal estimates of BMP implementation. Overall, low participation within the project area hindered the ability to quantify changes in water quality resulting from BMP implementation and prevented the project from meeting its phosphorus reduction goals. GL-035 LANDRUM, P.F., and W.S. DUPUIS. Toxicity and toxicokinetics of pentachlorophenol and carbaryl to Pontoporeia hoyi and Mvsis re- licta. In Aquatic Toxicology and Risk Assessment: Thirteenth Volume. ASTM STP 1096. W.G. Landis and W.H. van der Schalie, (eds.). American Society for Testing and Materials, Philadelphia, PA, 278-289 (1990). Two Great Lakes invertebrates, the amphipod Pontoporeia hoyi and the mysid shrimp Mvsis relicta. were exposed to pentachlorophenol (PCP) and carbaryl to determine acute mortality. At pH 8, the LCM for P. hovi after 96 h was 0.6 ± 0.3 mg ^L ' for PCP while that for carbaryl 101 was 0.23 ± 0.04 u.g mL1. The LCM for M. relicta at rll 8 and 96 h was 54.1 ± 10.3 u.g mL' for PCP and for carbaryl 0.23 u.g mL ' (0.103 - 0.356, n=2). The differences in the LCX values between P. hovi and M. relicta for PCP result in part from differences in the uptake clearances of the two animals, 3.1 ±0.9 mLg1 h1 for P. hovi compared to 0.4 ± 0.1 mL g ' h ' for M. relicta. A similar difference occurred in the respec- tive carbaryl uptake clearances for the two organisms, 3.74 ±0.63 mL g'1 h ' for P. hovi and 0.134 mL g'1 h ' (0.135 - 0.133, n=2) for M. re- licta. The cumulative toxicant concentrations in the organisms that result in 50% mortality, LD^,, were estimated from a toxicokinetics model that was parameterized with the measured uptake and elimination constants and the LCM values. The M. relicta LD.^ for PCP was approxi- mately ten times larger than that for P. hovi and confirmed the relative sensitivities of the organisms as described by their respective LC„ val- ues. For carbaryl, the LD^ for P. hovi was greater than that for M. relicta. Thus M. relicta is apparently more sensitive to accumulated car- baryl than P. hovi despite the similar LCM values for the two organisms. GL-036 LANDRUM, P.F., and C.R. STUBBLEFIELD. Role of respiration in the accumulation of organic xenobiotics by the amphipod Diporeia sp. Environmental Toxicology and Chemistry 10:1019-1028 (1991). Accumulation of hydrophobic organic xenobiotics is thought to occur by passive diffusion across the respiratory membrane of aquatic or- ganisms. This route has been confirmed with fish. However, aquatic invertebrates tend to remove organic xenobiotics from water much more efficiently than oxygen based on the relative uptake clearances. Uptake clearance is the rate coefficient that describes the volume of water stripped of analyte per g of organisms per h. For the amphipod Diporeia sp., formerly classified as Pontoporeia hovi. ratios of the contaminant uptake clearances to oxygen clearances were essentially constant at 3.9 ± 0.4 (X + SE) for ben7o(a)pyrene (BaP) 3.8 ± 0.3 for hexachlorobiphe- nyl (HCBP), and 4.2 ± 0.6 for phenanthrene (Phe). Therefore, based on the membrane transport efficiencies of nonpolar xenobiotics (60-80%) and oxygen (approximately 63%) in fish, and the uptake clearance for organic xenobiotics by Diporeia sp., either xenobiotics are accumulated through routes other than across the respiratory membrane or the accumulation efficiency of oxygen from water is much lower in amphipods that it is in fish. The variability in the uptake clearance for both BaP and HCBP was best described by regressions with the surface area-to-vol- ume ratio, whereas the uptake clearance for the more hydrophilic Phe was best described by a total surface area relationship. GL-037 LANDRUM, P.F., B.J. EADIE, and W.R. FAUST. Toxicokinetics and toxicity of a mixture of sediment-associated polycyclic aromatic hydrocarbons to the amphipod Diporeia sp. Environmental Toxicology and Chemistry 10:35-46 (1991). Amphipods, Diporeia sp., were exposed to a reference sediment dosed with two radiolabeled polycyclic aromatic hydrocarbons (PAHs) and sediments dosed with a mixture of PAHs at four concentrations: 21.4, 41.0, 1 19.6, and 327.0 nmol g'1 dry sediment, as the molar sum of the PAH congeners. Diporeia sp. were sampled for mortality and toxicokinetics for up to 26 d. Significant sediment avoidance was observed at the highest dose out to 6 d of exposure. The toxicity for the mixture was 38 ± 3% after 1 9 d of exposure at the highest dose, 327 nmol g"1 dry sediment as the molar sum of the PAHs. The measured organism concentration required to produce the mortality at day 19 was 2.9 |imol g"' as the sum of the bioaccumulated PAHs. The uptake clearance (g dry sediment g'1 organism h ') from sediments for the radiotracers increased with dose to an apparent plateau. Uptake clearance is the conditional constant relating the contaminant flux into the organisms to the contami- nant concentration in the referenced environmental compartment, in this case the sediment. This enhanced bioavailability with dose occurred even in the absence of overt effects and in the absence of changes in the measured partition coefficients for phenanthrene (273 ± 98) and pyrene (540 ±212), between the freely dissolved radiotracers in interstitial water and the sediment particles. These changes in bioavailability with changes in PAH concentration suggest that predictions of bioaccumulation of PAH congeners from sediments under different field concentra- tion conditions will not be possible with standard partitioning relationships. GL-038 Lindner, G., I. Greiner, R. Grom, K. Hain, M. Ibler, S. Kaminski, J. Kleiner, W. Pfeiffer, J.A. ROBBINS, O. Seewald, Ch. Wilhelm, and M. Wunderer. Removal and accumulation processes of Cesium radionuclides in prealpine lakes (German). Proceedings, Radiation Protec- tion for People and the Environment. Aachen, Germany, September 30-October 3, 1991. 6 pp. (1991). In prealpine lakes in southwest Germany, differences in the behavior of Cesium radionuclides from the Chernobyl fallout were observed, which are related to their limnological character. In Lake Constance, Cesium radionuclides introduced into the epilimnion were transferred to the sediment to a large extent already in May 1986 due to calcite precipitation and there dominantly deposited in an irreversible state. There- fore, the contamination of water and fish decreased rapidly and redissolution from sediment remains very small. In Vorsee and Schreckensee, on the other hand, a persistent input of Cesium radionuclides occurs from their swampy watersheds and from sediments due to redissolution, which is particularly high at low temperatures. Consequently, the decrease in the contamination of fish is considerably slower than in Lake Constance. GL-039 McCarthy, J.F., P.F. LANDRUM, and A. V. Palumbo. Organic contaminants in sediments: Biological processes. In Organic Substances and Sediments in Water. Volume 3: Biological, R.A. Baker, (ed.). Lewis Publishers, Chelsea, MI, 3-21 (1991). No abstract. 102 GL-040 McCORMICK, M.J. Potential changes in thermal structure and cycle of Lake Michigan due to global warming. Transactions of the American Fisheries Society 119:183-194 (19901 1 used a one-dimensional numerical model to estimate the present and possible future temperature structures in Lake Michigan. The esti- mates were based on model output from simulations of the 1981-1984 offshore temperature field. Once the water temperature climatology was estimated, I examined three scenarios based on general circulation models in which atmospheric C02 was doubled. The models were those of the Goddard Institute for Space Studies (GISS), the Geophysical Fluid Dynamics Laboratory (GFDL), and the Oregon State University (OSU). In general, simulations based on these three scenarios suggested that winter and summer heat contents of the lake would be higher than at present; the summer increase would be less than that in winter. The higher winter heat content would cause an earlier onset of full thermal stratification, and the season of stratification would increase by up to two months. The earlier onset of stratification, coupled with little change in the wind stress pattern, would yield stronger stratification and less energy for large-scale vertical mixing. The GISS and GFDL scenarios suggest that the lake may not fully turn over in most winters, so a permanent thermocline may form in the deeper regions of Lake Michigan, below the shallow seasonal thermocline. Should future wind speeds be reduced from those I used here, sensitivity analyses suggest that the true effect on the annual thermal cycle and structure may be underestimated. Furthermore, given all of the uncertainties surrounding estimates of future climate, these results are best viewed as a sensitivity study, wherein the scales selected for the sensitivity tests are based upon the dif- ferent general circulation model scenarios. GL-041 McCORMICK, M.J., R.L. Pickett, and G.S. MILLER. A field evaluation of new satellite-tracked buoys: A LORAN-C position recording and a sonobuoy type drifter. Marine Technology Society Journal 25(2):29-33 (1991). Two types of satellite-tracked, drifting data buoys were tested in Lake Michigan for twenty days. One type was a sonobuoy-size (0.9 m long, 12 cm diameter) buoy made by Metocean Data Systems and one was a mid-sized (1.8 m long, 20 cm diameter) buoy made by Polar Re- search Laboratory. The two Metocean buoys came equipped with sensors for barometric pressure, air temperature, and seven levels of water temperature from the surface down to 100 m. The Polar Research buoy was without sensors and was modified to carry a LORAN-C position- recording system. The Metocean buoy sensors compared well with those of the National Oceanic and Atmospheric Administration (NOAA) meteorological buoy in the center of Lake Michigan and with the Conductivity, Temperature, Depth (CTD) data taken at the launch site. Shortly after launch, however, the bottom weight broke off one of the subsurface temperature cables on these buoys. This failure allowed the temperature cable to stream along near the surface so that no buoy, however, provided useful subsurface data for fifteen days until its ballast weight was lost after contact with bottom. The add-on LORAN positioning on the Polar Research buoy provided more frequent and precise positions than were available from satellite tracking alone. The LORAN-C data suggest that infrequent yet large satellite positioning errors may occur and may be difficult for the user to detect. GL-042 NALEPA, T.F. Long-term declines in freshwater mussels (Bivalvia:Unionidae) of the western basin of Lake Erie. Journal of Great Lakes Research 17(2):214-219 (1991). Long-term trends in the abundance of unionids in the western basin of Lake Erie were examined from data collected at 17 stations in 1961 , 1972, and 1982. The mean number of unionids at these stations declined over this time period, decreasing from 10 m 2 in 1961, to 6 m~2 in 1972, down to 4 m~2 in 1982. This decline in abundance was reflected in the decrease in the number of stations where mussels were found; unionids were found at 16 of the 17 stations in 1961, but at only 6 stations in 1982. Reasons for the decrease in the unionid population are not generally apparent, but are probably related to the decline in water quality and periods of low oxygen levels over the time period of the surveys. GL-043 NALEPA, T.F. Status and trends of the Lake Ontario macrobenthos. Canadian Journal of Fisheries and Aquatic Sciences 48(8):1558- 1567(1991). The benthic macroinvertebrate community of Lake Ontario was examined relative to communities found in the other Great I^akes and also relative to trends over time. In the nearshore, populations are heavily influenced by municipal and industrial inputs. For example, oligochaete abundances in the nearshore are higher than in any of the other Great Lakes (excluding shallow Lake Erie), communities have been altered even to relatively deep depths near the major river mouths, and the pollution-sensitive Pontoporeia hovi is scarce along the southern shoreline east of the Niagara River mouth. In the profunda!, benthic composition is similar to that found in the other Great Lakes, but biomass is less than might be expected given the amount of organic material settling to the bottom. Benthic standing stocks in this region have apparently de- clined almost threefold since the 1960s. Reasons for this decline do not appear to be related to trends in water column productivity or to preda- tion pressure, but may be related to the accumulation of contaminants. Research needs include studies to assess benthic trends over a much broader area of the lake and studies to examine the impact of sublethal levels of contaminants. GL-044 QUINN, F.H. Great Lakes water level statistics and decision malting. Proceedings, Great Lakes Water Level Forecasting and Statistics Symposium, Windsor, Ontario, Canada, May 17-18, 1990. Great Lakes Commission, Ann Arbor, MI, 205-209 (1990). 103 The Laurentian Great Lakes comprise one of the major water resources of North America. Planning for the future use and development around the Great Lakes requires a knowledge of past and potential future water level fluctuations. An excellent database of monthly water lev- els exists from 1860 to present with some additional data back to 1800. This data can be used to derive statistics to assist in decision making for varying planning horizons into the future. Statistical analysis of Great Lakes water levels is different from riverine systems because of long term persistence due to the large lakes surface areas and limited outlet capacity. The lake level variability and range are also dependent upon the climatic regime that is in effect. In addition, for about 1 2 years into the future, lake levels are conditionally dependent upon the current lake level. A major challenge is to analyze and present lake level statistics in such a way as to provide meaningful data for engineers, planners, wa- ter resource managers and others who are responsible for decisions based on future water level fluctuations. GL-045 QUINN.F.H. Proposed climate analog scenariosfortheDCPhaselllevels study reference. Proceedings, A Symposium on Climate Scenarios, University of Waterloo, Waterloo, Ontario, Canada, June 12, 1991. 59-66 (1991). No abstract. GL-046 ROBBINS, J.A., and B.J. EADIE. Seasonal cycling of trace elements ,37Cs, 7Be, and wwopu in Lake Michigan. Journal of Geophysical Research 96(C9):17081-17104 (1991). Trace elements, fallout "7Cs (t1/2=30.2 years) and cosmogenic 7Be (t)/2=53.4 days) were measured in trap samples collected from two sites in southern Lake Michigan at selected times during the period from 1982 through 1987. Concentrations of ,37Cs in trap material were virtually constant from top to bottom during the period when the lake was vertically well-mixed. Fluxes of ir7Cs were more than two orders of magni- tude higher than atmospheric loading. With the development of the thermocline, concentrations of the isotope diminished to undetectable lev- els at a rate indicating a 1 -month residence time of resuspended components in the epilimnion. Declines in mass flux (10 to 0.2 g m2 d1) and trace element concentrations (some by 30 x) also occurred at this time. Epilimnetic concentration of 7Be increased from a prestratification value of about 30 dpm/g to a maximum of about 120 dpm/g in July. During calcite formation in August, the concentration rapidly declined mainly as a result of enhanced particle settling rates. Throughout the period of stratification, a maximum in concentration and flux of 7Be per- sisted in trap material between 40 and 60 m depth but only about 15% of the atmospheric flux was transferred to the benthic boundary region below 60 m. In near-bottom trap materials, the 137Cs concentration was reduced at the onset of stratification by addition of radiocesium-defi- cient authigenic materials. By November, concentrations of 137Cs had returned to prestratification levels through remineralization of these ma- terials. A decrease of 22% in the seasonally invariant ratio of '"Cs/^K between 1982 and 1986 indicated a decay-corrected removal time of about 20 years, which is consistent with the rate of decrease of Pu concentrations in the well-mixed water column measured over more than a decade. In benthic trap samples, 7Be concentration decreased exponentially throughout the stratified period, with a time constant comparable to the half -life of the isotope. The resuspendable sediment pool, evidently isolated from atmospheric loading during stratification, was "re- charged" with 7Be following late fall overturn. Box and advection-diffusion models describing the storage and vertical distribution of 7Be dur- ing the winter-mixing period successfully account for observations, implying an inverse relation between water depth and winter recharging of the resuspendable pool. A plutonium -calibrated box model for the seasonal cycle of tracers in surface waters describes the main features of the variation of Pu isotopes, l37Cs and 7Be. GL-047 ROBBINS, J.A., and N.R. MOREHEAD. Rates of accumulation of recent sediments in Lake Ontario as determined by Cs-137 and Pb-210. Interagency Agreement Number DW1 3933058-01-0, U.S. Environmental Protection Agency, Washington, DC, 66 pp. (1991). As part of a multi-institutional study of contaminant mass balance and accumulation history in Lake Ontario, sediment cores were collected from 37 sites in August 1987. All cores were analyzed for fallout Cs-137 to obtain focusing factors useful for contaminant inventory determi- nations. Ten cores were dated using both Cs-137 and Pb-210. Lake Ontario sediments store most of the Cs-137 which was deposited on the lake surface mainly as a result of atmospheric nuclear testing in the 1960s. The amount stored varies strongly with coring site and is generally focused most intensely in depositional basins. Focusing fac- tors, varying in this study by more than a factor of 40 from site to site, can be used with suitable qualifications to improve the accuracy of lake- wide contaminant mass balances. A constant sedimentation rate model (RSSM) and variable sedimentation rate model (VSR) were applied in- dependently to Cs-137 and Pb-210 distributions to infer mixing scale-lengths, sedimentation rates and chronologies. The VSR model improved the consistency of rates as determined by the two radiotracer methods and showed (1) sedimentation rates vary in nine cores studied by more than an order of magnitude (0.024 to 0.292 g cm 2 yr1), and (2) that since roughly 1920 there has been a marked increase in rates relative to pre- modem (baseline) values. Changes ranged from 14 to 50% at sites depending on baseline sedimentation rates. By subtracting individual base- line rates, it is shown that all cores have recorded essentially the same time-dependent increase in accumulation rate in the Lake. Age-depth re- lations based on RSSM and VSR analysis are presented in graphical form as part of the report text while age-depth tables useful in conjunction with contaminant distribution measurements in companion cores can be found in the tables of the Appendix: RSSM (Appendix D), VSR (Ap- pendix F). 104 1 GL-048 Seitzinger, S.P., W.S. GARDNER, and A.K. Spratt, The effect of salinity on ammonium sorption in aquatic sediments: Implications for benthic nutrient recycling. Estuaries 14(2):167-174 (1991). Ambient exchangeable ammonium concentrations in freshwater sediments are generally considerably greater than those reported for ma- rine sediments. Laboratory measurements indicate that competition for cation exchange sites by ions in seawater is a factor responsible for the lower exchangeable ammonium concentrations in marine sediments. Exchangeable ammonium concentrations were 3- to 6-fold higher when river and estuarine sediments were incubated with fresh water relative to the same sediments incubated with salt water (% = 23). A model was developed to explore the implications for benthic nitrogen cycling of this salinity effect on exchangeable ammonium concentrations. Ammo- nium diffusion, exchangeable and dissolved ammonium concentrations, and nitrification rates were components of the model formulation. The model output suggests that higher exchangeable ammonium concentrations predicted in fresh water relative to marine sediments can markedly increase the fraction of the ammonium produced in sediments that is nitrified (and subsequently denitrified). These results are consistent with field and experimental laboratory data which indicate that a larger percentage of net ammonium production in aerobic fresh water sediments is nitrified and denitrified (80-100%) relative to marine sediments (40-60%). GL-049 VANDERPLOEG, H. A. Feeding mechanisms and particle selection in suspension-feeding zooplankton. In The Biology of Particles in Aquatic Systems. R.S. Wotton (ed.). CRC Press, Inc., Boca Raton, FL, 1 83-212 (1990). No abstract. Addendum GL-050 QUINN, F.H. Likely effects of climate changes on water levels in the Great Lakes. Proceedings, First North American Conference on Preparing for Climate Change: A Cooperative Approach, Washington, DC, October 27-29, 1987. Climate Institute, Washington, DC, 481- 487 (1988). No abstract. GL-051 QUINN, F.H. Fluctuations of Great Lakes water levels. In Great Lakes Water Levels: Shoreline Dilemmas. Water Science and Technol- ogy Board Colloquium Series. National Academy Press, Washington, DC, 13-24 (1989). No abstract. 105 NATIONAL SEVERE STORMS LABORATORY NS-001 AUGUSTINE, J.A., and K.W. HOWARD. Mesoscale convective complexes over the United States during 1986 and 1987. Monthly Weather Review 119:1575-1589 (1991). Infrared imagery from GOES was used to document mesoscale convective complexes (MCCs) over the United States during 1986 and 1987. A near-record 58 MCCs occurred in 1986, and 44 occurred in 1987. Although these totals were above average relative to MCC numbers of the 7 years prior to 1985, seasonal distributions for both years were atypical. Particularly, each had an extended period (about 3 weeks) when no MCCs occurred in late spring and early summer, a time when the mean MCC seasonal distribution peaks. This peculiarity was investigated by comparing mean large-scale surface and upper-air environments of null- and active-MCC periods of both years. Results confirmed the primary importance to MCC development of strong low-level thermal forcing, as well as proper vertical phasing of favorable lower- and midtropospheric environments. A cursory survey of MCCs documented outside of the United States reveals that MCCs, or MCC-type storms, are a warm-season phenomenon of midlatitude, subtropical, and low-latitude regions around the globe. They have been documented in South America, Mexico, Europe, West Africa, and China. These storm systems are similar to United States MCCs in that they are nocturnal, persist for over 10 h, tend to develop within weak synoptic-scale dynamics in response to strong low-level thermal forcing and conditional instability, and occur typically downwind (midlevel) of elevated terrain. It is surmised that MCCs probably occur over other parts of the midlatitudes, subtropics, and low latitudes that have yet to be surveyed. NS-002 Balakrishnan, N., D.S. ZRNIC, K. Aydin, V. Chandrasekar, V.N. Bringi, and C.L. ZIEGLER. Polarimetric signatures in the stratiform region of a mesoscale convective system. 25th International Conference on Radar Meteorology, Paris, France, June 24- 28, 1991. American Meteorological Society, Boston, 525-528 (1991). No abstract. NS-003 Banjanin, Z.B., and D.S. ZRNIC. Clutter rejection for Doppler weather radars which use staggered pulses. IEEE Transactions on Geoscience and Remote Sensing 29 (4): 610-620 (1991). Several methods for canceling ground clutter in Doppler weather radars which operate with staggered PRTs are investigated. A scheme is developed which consists of two filters that operate sequentially, so that the overall filter is time varying, with periodically changing coefficients. This filter is analyzed theoretically and through simulations for a stagger ratio of 3/2, which extends the unambiguous velocity interval. The amplitude characteristic of the filter over this interval is very good, but the phase characteristic, which is nonlinear in a small part of the interval, requires that a special decision logic be used for velocity estimation. At an SNR of 10 dB, mean velocity estimates at the output have average errors smaller than 3.5% (i.e., 1.75 m s'1 for the extended unambiguous interval of 2vm = 50 m s"1); thus the scheme could be suitable for operation in environments with ground clutter. NS-004 BARTELS, D.L., D.P. JORGENSEN, and B.F. SMULL. Airborne Doppler analysis of a mesoscale convective system observed during the SW Area Monsoon Project. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 486-489 (1991). No abstract. NS-005 BARTELS, D.L., and R.A MADDOX. Midlevel cyclonic vortices generated by mesoscale convective systems. Monthly Weather Review 119:104-118 (1991). Despite the large number of convective systems that occur over the central United States every year, there are typically a few well-defined, midlevel vortices apparent in satellite imagery after the overlying anvil debris from some convective complexes has dissipated or advected away. A climatology of mesoscale convectively generated vortex (MCV) events for 1981-1988 is presented and the synoptic setting in which the circulation becomes apparent is discussed. Proximity sounding data from numerous cases are used to examine features of the kinematic and thermodynamic setting of MCVs at various lifecycle stages defined by satellite imagery. 106 Features of the large-scale environment that appear conducive to the formation and longevity of MCVs include weak flow, weak vertical shear, weak background relative vorticity, and intense horizontal and vertical moisture gradients. The rapid mesovortex generation observed can be explained by the stretching term of the vorticity equation. Most MCVs emerge from MCC-type (i.e., circular) systems, but of the cases noted (24 cases over the central United States between 1981-1988) only half originated in systems that met Maddox's stringent MCC size and duration criteria. Furthermore, since several MCVs emerged from small and relatively short-lived convective systems, the background synoptic environment, in addition to the magnitude of latent heating, may provide important controlling factors in determining which MCSs will lead to documentable MCVs. The majority of MCVs (i.e., 80%) were first observed at latitudes south of 40°N. Since many convective systems occur at latitudes north of 40°N, the paucity of MCVs in northern latitudes is not the result of a lack of convective systems. NS-006 Bluestein, H.B., S.D. Hrebenach, and E.A BRANDES. A test of the synthetic dual-Doppler analysis technique: Two case studies. 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 634-637 (1991) No abstract. NS-007 BRANDES, E.A Severe turbulence with a low-level jet ahead of a squall line. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990, American Meteorological Society, Boston, 141-145 (1990). No abstract. NS-008 BRANDES, E.A., and R.M. RABIN. Probing a nonprecipitating cold front with Doppler weather radar. Journal of Atmospheric and Oceanic Technology 8 (3): 409-421 (1991). The utility of Doppler radar to study boundary-layer kinematics of a weak nonprecipitating cold front in Oklahoma on 16 October 1987 was examined with measurements from two radar. Diagnosis was impeded by operation at low antenna elevation angles, short radar ranges, and low signal-to-noise ratios. Further, kinematic parameters computed by single-radar velocity-azimuth-display (VAD) technique for meteorological vavelengths < 125 km were significantly smoother (more than 50% attenuated). Meteorological scales > 5 km were well resolved (less than 50% attenuated) in wind fields synthesized from dual-Doppler radar observations, but derived parameters were particularly sensitive to the vertical extrapolation of radial velocity measurements in the presence of strong vertical wind shear. Nonetheless, radar-derived wind flows depicted a sequence of events consistent with other instrumentation. In the vicinity of the front, mean-flow divergence, vertical velocity, and deformation, computed from single-radar measurements for an analysis domain of 30-km radius, were -4 x 10'5 s"1, 3 cm s"1, and 16 x 10"5 s'\ respectively. Agreement between the radars attested to the accuracy of the measurements. Local peak absolute values of divergence, deformation, and vertical vorticity, determined from dual- Doppler analysis, were 200-300(x 10"5)s_1. Extrema were concentrated along the frontal zone where signals were strong, and had dimensions of - 10 km. NS-009 BRANDES, E.A, D.S. ZRNIC, G.E. Klazura, C.F. Suprenant, and D. Sirmans. The next generation weather radar (WSR-88D) as an applied research tool. 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 47-50 (1991). No abstract. NS-010 Bringi, V.N, V. Chandrasekar, N. Balakrishnan, and D.S. ZRNIC. An examination of propagation effects in rainfall on radar measurements at microwave frequencies. Journal of Atmospheric and Oceanic Technology 7 (6): 829-840 (1990). Propagation effects in rainfall are examined at three microwave frequencies corresponding to S(3.0 GHz), C(5.5 GHz), and X(10.0 GHz) bands. Attenuation at horizontal polarization, as well as differential attenuation and differential propagation phase between horizontal (H) and vertical (V) polarizations are considered. It is shown that at the three frequencies both attenuation and differential attenuation are nearly linearly related to differential propagation phase (0pjp)- Th's is shown through simulation using (a) gamma raindrop size distributions (RSD) with three parameters (N0, Dq, m) that are varied over a very wide range representing a variety of rainfall types, and (b) measured raindrop size distributions at a single location using a disdrometer. Measurements of X-band specific 107 attenuation and S-band specific differential phase in convective rainshafts using the National Center for Atmospheric Research CP-2 radar are presented in order to experimentally demonstrate the linear relationship between attenuation and differential propagation phase. Correction procedures for reflectivity and differential reflectivity (ZDR) are developed assuming that differential propagation phase is measured using a radar that alternately transmits H and V polarized waves with copolar reception through the same receiver and processor system. The correction procedures are not dependent on the actual rainrate profile between the radar and the range location of interest. The accuracy of the procedure depends on, (a) RSD fluctuations, (b)variability in the estimate of differential propagation phase due to measurement fluctuations, and (c) nonzero values of the backscatter differential phase (S) between H and V polarizations. Simulations are used to gauge the accuracy of correction procedures at S- and C-bands assuming S is negligible. The correction accuracy for attenuation at S-band is estimated to be -0.05 dB while at C-band it is estimated to be within 1 dB if 0DP < 60°. Simulations further indicate that C-band differential attenuations effects can be corrected to within -35% of the mean value. NS-011 BROWN, R.A. Characteristics of supercell hodographs. Preprints, 16th Conference on Severe Local Storms, October 22-26, 1990, Kananaskis Provincial Park, Alberta, Canada. American Meteorological Society, Boston, 30-33 (1990). No abstract. NS-012 BROWN, R.A, and V.T. WOOD. On the interpretation of single-DoppIer velocity patterns within severe thunderstorms. Weather and Forecasting 6 (1): 32-48(1991). Although the flow field within a severe thunderstorm is complex, it is possible to simulate the basic features using simple analytical flow models (such as uniform flow, axisymmetric rotation, axisymmetric divergence). Combinations of such flow models are used to produce simulated Doppler velocity patterns that can be used as "signatures" for identifying quasi-horizontal flow features within severe thunderstorms. Some of these flow features are: convergence in the lower portions of a storm and divergence in the upper portions associated with a strong updraft, surface divergence associated with a wet or dry downdraft, mesocyclone (rotating updraft), flow around an updraft obstacle, and tornado. Recognition of the associated Doppler velocity patterns can aid in the interpretation of single-Doppler radar measurements that include only the radial component of flow in the radar viewing direction. NS-013 BURGESS, D.W., and B.F. SMULL. Doppler radar observations of a bow echo associated with a long-track severe windstorm. Preprints, 16th Conference on Severe Local Storms, Kananaskis Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, 203-208 (1990). No abstract. NS-014 CARACENA F., R.L. HOLLE, and C.A. DOSWELL III. Microbursts: A spotters' guide. National Severe Storms Laboratory, Environmental Research Laboratories, NOAA Boulder, CO, poster, 1 pp. (1991). No abstract. NS-015 Chandrasekar, V., V.N. Bringi, N. Balakrishnan, and D.S. ZRNIC. Error structure of multiparameter radar and surface measurements of rainfall. Part III: Specific differential phase. Journal of Atmospheric and Oceanic Technology 7 (5): 621-629 (1990). Parts I and II of this three part paper dealt with the error structure of differential reflectivity and X-band specific attenuation in rainfall as estimated by radar and surface disdrometers. In this part III paper we focus on the error structure of the specific differential phase (KDP, "km"1) measurement in rainfall. This allows us to analyze three estimators of rainfall rate, the first based on the reflectivity factor ZH, the second based on combining reflectivity and ZDR, [R(ZH, ZDR)], and the third based on KDP alone, R(KDP). Simulations are used to model random errors in ZH, ZDR, and KDP. Physical variations in the raindrop size distribution (RSD) are modeled by varying the gamma parameters (Nq, D0, m) over a range typically found in natural rainfall. Thus, our simulations incorporate physical fluctuations onto which random measurements errors have been superimposed. Radar-derived estimates of R(ZH, ZDR) and R(KDP) have been intercompared using data obtained in convective rainfall with the NSSL Cimarron radar and the NCAR/CP-2 radar. As practical application of the analysis presented here, we have determined the range of applicability of the three rainfall rate estimators: R(ZH), R(ZH, ZDR) and R(KDP). Our simulations show that when the rainfall rate exceeds about 70 mm h"\ R(KDP) performs better than R(ZH, ZDR). This result is valid over a 1 km propagation path. At 108 intermediate rainfall rates around 20 < R < 70 mm h , our simulations show that R(ZH, ZDR) gives the least error. However, there are other reasons which make R(KDP) useful; (i) its stability with respect to mixed phase precipitation, and (ii) the fact that it is a differential phase measurement and thus insensitive to system gain calibration. This last premise suggests an accurate method of system gain calibration based on the rain medium. NS-016 DAVIES-JONES, R.P. The frontogenetical forcing of secondary circulations. Part I: The duality and generalization of the Q vector. Journal of the Atmospheric Sciences 48 (4): 497-509 (1991). Hoskins, Draghici, and others have shown that the Q vector is an important quantity in quasi-geostrophic (QG) theory for the diagnosis of ageostrophic circulations. In this paper, a vorticity dynamics perspective is used to develop a generalized Q vector, Q*. An equation that relates the material derivative of the thermal-wind imbalance vector to Q* and ageostrophic terms in isentropic flow is obtained from the primitive equations (PE). The generalized Q vector is the vector mean of two terms: a frontogenetical vector that, for horizontal isentropic flow, is equal to the vector frontogenesis function F, and a vortex stretching term proportional to the stretching and reorientation of vorticity by the horizontal wind. Invoking just one QG assumption, the substitution of geostrophic for total velocity gradients, reduces Q* to Q and leads directly to the omega equation of QG theory. The frontogenetical and vortex stretching parts of the generalized Q vector of PE theory become equal in the QG limit. Thus, the conventional Q vector has dual physical interpretations in terms of vorticity and thermodynamic properties. The divergence of the Q vector in its vortex stretching form is equal to the forcing term in Sutcliffe, Wiin-Nielsen, and Trenberth version of the omega equation. The self-destruction of balanced flow and its restoration by vertical secondary circulations is explained in terms of entropy and vorticity properties. A new assumption (Alternative Balance of AB) consists of omitting the material derivative of the thermal-wind imbalance vector, so that thermal-wind balance is restored instantaneously by secondary circulations. This approximation reduces the PE omega and secondary circulation equations to diagnostic forms resembling their QG equivalents, except for the replacement of Q by Q*. Under the AB assumption, the Q* vector points toward rising motion and inertial gravity waves are excluded. NS-017 DAVIES-JONES, R.P., and D.W. BURGESS. Test of helicity as a tornado forecast parameter. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, 588-592 (1990). No abstract. NS-018 DOSWELL, C.A III. A point of clarification about area and energy on common thermodynamic diagrams. Weather and Forecasting 6 (2): 300-301 (1991). No abstract. NS-019 DOSWELL C.A.III. A review for forecasters on the application of hodographs to forecasting severe thunderstorms. National Weather Digest 16 (1): 16 pp (1991). Basics of the hodograph are reviewed in order to acquaint (or re-acquaint) forecasters with this useful tool for diagnosis of vertical wind shear. This review makes use of existing operational programs for hodograph analysis, as well as presenting the principles underlying their use. A brief summary is given of the physical processes acting to create vertical wind shear. These processes provide the basis for interpretation of the hodograph and an understanding of them allows one to make subjective hodograph prognoses. Finally, an explanation for the concepts of streamwise vorticity and helicity is given, emphasizing the importance of viewing them in a storm-relative framework. A representative set of references is provided, as well, to guide the forecaster in developing enough understanding of hodographs to apply them to severe thunderstorm forecasting. NS-020 DOSWELL, C.A III. Comments on the February 1990 Digest Article, "On the need for augmentation in automated surface observations". National Weather Digest 15: (3) 29-30 (1990). No abstract. 109 NS-021 DOSWELL, C.A.III. Comments on mesoscale convective patterns of the southern high plains. Bulletin of the American Meteorological Society 72 (3): 389-390: (1991). No abstract. NS-022 DOSWELL, C.A. Ill, and S.L. BARNES. Comments on "The theoretical, discrete, and actual response of the Barnes objective analysis scheme for one- and two-dimensional fields. Monthly Weather Review 119 (6): 1490-1492 (1991). No abstract. NS-023 DOSWELL, C.A III, R.P. DAVIES-JONES, and D.L. KELLER. On summary measures of skill in rare event forecasting based on contingency tables. Weather and Forecasting 5 (4): 576-585 (1990). The so-called True Skill Statistic (TSS) and the Heidke Skill Score (S), as used in the context of the contingency table approach to forecast verification, are compared. It is shown that the TSS approaches the Probability of Detection (POD) whenever the forecasting is dominated by correct forecasts of nonoccurrence, i.e., forecasting rare events like severe local storms. This means that the TSS is vulnerable to "hedging" in rare event forecasting. The S-statistic is shown to be superior to the TSS in this situation, accounting for correct forecasts of null events in a controlled fashion. It turns out that the TSS and S values are related in a subtle way, becoming identical when the expected values (due to chance in a k x k contingency table) remain unchanged when comparing the actual forecast table to that of a hypothetical perfect set of forecasts. Examples of the behavior of the TSS and S values in different situations are provided which support the recommendation that S be used in preference to TSS for rare event forecasting. A geometrical interpretation is also given for certain aspects of the 2x2 contingency table and this generalized to the k x 1 case. Using this geometrical interpretation, it is shown to be possible to apply dichotomous verification techniques in polychotomous situations, thus allowing a direct comparison between dichotomous and polychotomous forecasting. NS-024 DOSWELL, C.A., III, DAVIES-JONES, R.P., and D.L. KELLER. Reply to comments on " On summary measures of skill in rare event forecasting based on contingency tables. Weather and Forecasting 6 (3): 403 (1991). No abstract. NS-025 DOSWELL, C.A.III, D.L. KELLER, and S.J. Weiss. An analysis of the temporal and spatial variation of tornado and severe thunderstorm watch verification. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, 294-299 (1990). No abstract. NS-026 DOSWELL, C.A.III, A.R. Moller, and R. Przybylinski. A unified set of conceptual models of variations on the supercell theme. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1991. American Meteorological Society, Boston, 40-45 (1990). No abstract. NS-027 DOUGLAS, M.W. Cost-effective upper-wind observing networks for developing countries. The SWAMP example. Extended abstracts, Second Symposium on Tropospheric Profiling: Needs and Technologies, Boulder, CO, September 9-13, 1991. National Center for Atmospheric Research, National Oceanic and Atmospheric Administration, American Meteorological Society, German Meteorological Society, and Cost-74, 115-116 (1991). No abstract. 110 NS-028 DOUGLAS, M.W. The selection and use of dropwindsonde-equipped aircraft for operational forecasting applications. Bulletin of the American Meteorological Society 71:1746-1757 (1990). This article discusses the feasibility of using dropwindsonde-equipped aircraft to obtain meteorological observations over oceanic data-void areas for operational forecasting applications. Such in-situ meteorological observations would provide measurements of wind, temperature, and moisture at a higher vertical resolution and greater accuracy than currently available from satellite-derived observations. Such airborne observations, if globally obtained, would greatly enhance global datasets for both numerical weather prediction and for research studies of large-scale phenomena, such as the El Nino/Southern Oscillation. The aircraft could also serve as platforms for collecting frequent oceanic thermal and current information. The advantages and limitations of a dropwindsonde-based observing system are compared with current and proposed ground- and satellite-based systems. NS-029 DOUGLAS, M.W., L.S. FEDOR, and M.A SHAPIRO. Mesoscale structure of the cold frontal zone of a rapidly deepening cyclone over the North Pacific Ocean. Preprints, First International Winter Storm Symposium, New Orleans, LA January 15-18, 1991. American Meteorological Society, Boston, 387-392 (1991). No abstract. NS-030 DOUGLAS, M.W., L.S. FEDOR, and M.A. SHAPIRO. Polar low structure over the northern Gulf of Alaska based on research aircraft observations. Monthly Weather Review 119:32-54 (1991). During the 1987 Alaska Storms Program, a polar low that developed over the northern Gulf of Alaska was investigated during two flights by a WP-3D research aircraft on successive days. Analyses based on data obtained from omega dropwindsondes during the first flight showed the small (about 300 km) horizontal scale of the vortex. The vortex center was characterized by suppressed cloudiness on both days and was decidedly warmer at low levels than its surroundings. The vorticity associated with the polar low was largest near the surface and decreased rapidly with height on the first day, with only a very weak circulation evident by 700 mb. Coldest 500-mb temperatures and lowest static stabilities were found directly above the surface low. On the second day the vortex was more intense at midtropospheric levels than on the previous day, and convective clouds extended to higher levels. NS-031 DOVIAK, R.J., S.S. Chen, and D.R. Christie. A thunderstorm-generated solitary wave observation compared with theory for nonlinear waves in a sheared atmosphere. Journal of the Atmospheric Sciences 48 (1): 87-111 (1991). The theory of internal nonlinear waves in a motionless medium is extended to waves in sheared flow to provide a basis for the interpretation of atmospheric solitary waves. It is shown that if the Scorer parameter is zero in a semi-infinite upper region, the integro-differential equation [i.e., the Benjamin-Davis-Ono (BDO) equation] defining the evolution of nonlinear waves in sheared flow is independent of shear and stability in the upper layer. A new type of evolution model is presented, based on the numerical solution of the BDO equation, for the generation of solitary waves by a thunderstorm moving at supercritical speeds. The results of a thorough study of observations of a thunderstorm-generated solitary wave are presented in detail. These observations show that some of the storm's outflow, which was denser than the environment through which the wave propagated, was trapped in the interior of the wave. It is hypothesized that the Coriolis force then caused this denser air to flow along the axis of the wave away from the storm's southern flank for distances in excess of 100 km. Analysis reveals that the temporarily trapped recirculating air in the leading solitary wave is gradually deposited along the ground, forming an advancing shallow layer of denser air behind the wave. The derived wave parameters are then compared with theory. A new type of analysis, based on the separation of the wind change due to vertical transport of horizontal momentum from the observed wind perturbations, results in improved agreement between weakly nonlinear theory and observations. This analysis supports the deduction that wave energy propagates along straight rays, parallel to the plane of recirculating flow, but oblique to the curved wave front. The failure of weakly nonlinear theory to account for all the observed wave characteristics is shown to be caused by the presence of recirculating flow. Comparison with numerical results for strongly nonlinear waves shows reasonably good agreement for all the wave characteristics, except wave speed, which is significantly less than that predicted when wave amplitudes are large. Finally, relations are developed that govern the minimum wave amplitude threshold required for the propagation of solitary waves in waveguides bordered by weakly stratifies sheared flow. NS-032 DOVIAK, R.J., and D.R. Christie. Buoyancy wave hazards to aviation. Preprints, 4th International Conference on Aviation Weather Systems, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 247-252 (1991). No abstract. Ill NS-033 EILTS, M.D., E.D. MITCHELL, and K. Hondl. The use of Doppler radar to help forecast the development of thunderstorms. Preprints, 29th Aerospace Sciences Meeting, AIAA-91-0261, Reno, Nevada, January, 1991. 7 pp (1991). An operational Doppler weather radar (WSR-88D/NEXRAD) will be installed during 1991 at the Melbourne, Florida Weather Forecast Office which is approximately 50 km away from Kennedy Space Center. This study examines how the WSR-88D Doppler radar could be used to help precisely forecast the location and timing of the initiation of thunderstorms both over KSC and in general over central Florida. The data used for this study were collected as part of a test of the FAA's Terminal Doppler Weather Radar program which was conducted during the summer of 1990 near Orlando, Florida. Doppler radar data were collected with high temporal (2.5 minute update) and spatial resolution throughout the troposphere during this test. It was found that a 10 dBZ cell, detected at a height above 4 km AGL and located over a radar-detected surface convergence boundary, is a reliable signature of the initiation of thunderstorms. On average, a 13 minute lead time was observed between the detection of this signature and the first cloud-to-ground lightning strike. NS-034 EILTS, M.D., S.H. Olson, G.J. Stumpf, L.G. HERMES, A Abrevaya, J. Culbert, K.W. Thomas, K Hondl, and D. Klingle- Wilson. An improved gust front detection algorithm for the TDWR. 4th International Conference on Aviation Weather Systems, Paris, France, June 24-28. American Meteorological Society, J37-J42 (1991). No abstract. NS-035 Elliott, R.L., K.C. Crawford, F. Brock, G.W. Cuperus, S.J. Stadler, H.L. Johnson, and C.A DOSWELL III. Mesonet: Oklahoma's automated weather network. Report International Summer Meeting, Albuquerque, NM, June 23-26, 1991. The American Society of Agricultural Engineers, St. Joseph, MI, 9 pp, (1991). A unique, state-wide "mesonetwork" of automated weather stations is being established in Oklahoma. This multi-purpose network will collect data from more than 100 remote stations at 15-minute intervals. Several methods will be used to disseminate weather information (data and value-added products) for a variety of applications. NS-036 FREDRICKSON, S., and J.M. LEWIS. Validation of the NOAA SST analysis over the loop current using in situ data. Preprints, 5th Conference on Meteorology and Oceanography of the Coastal, Miami, Florida, May 6-10, 1991. American Meteorological Society, Boston, 76-80 (1991). No abstract NS-037 HERMES, L.G. Comparisons of rawinsonde-deduced kinematic and thermodynamic quantities with those deduced from VHF profiler observations. Monthly Weather Review 119 (7): 1693-1712 (1991). The testing and evaluation of new observing systems (i.e., 50-MHz wind profilers) was listed among the goals of the 1985 Oklahoma-Kansas Preliminary Regional Experiment for STORM-Central (PRE-STORM). Using a PRE-STORM data set from 12-13 May 1985, kinematic quantities computed from profiler winds are quantitatively compared with those computed from a dense network of rawinsonde wind observations. Both the generalized thermal wind equation and the geostrophic thermal wind equation are used to retrieve horizontal gradients of virtual temperature from the profiler wind observations. The resultant gradients are compared with those computed from rawinsonde temperature and moisture measurements. Comparisons of the kinematic quantities computed from the two data sources show some agreement in temporal trends. Comparisons of the detailed structure reveal significant differences. The temporal trends of the vertical motion fields obtained from the profilers and rawinsondes do not correspond. The virtual temperature gradients retrieved using profiler winds and the generalized thermal wind equation do not agree with those computed from rawinsonde temperature and humidity data. Overall, the use of the thermal wind equation and profiler wind observations to estimate thermal gradients was not successful. An example of detailed thermal structure from rawinsonde temperature and humidity data that was successfully detected using profiler winds and the generalized thermal wind equation is presented. The sampling characteristics and other sources of errors that hinder comprehensive comparisons of the observations from the various PRE-STORM sensors are discussed. 112 NS-038 HERMES, L.G. Detection of microburst-related gust fronts using doppler radar. 4th International Conference on Aviation Weather System, Paris, France, June, 24-28, 1991. American Meteorological Society, Boston, 76-80 (1991). No abstract. NS-039 HERMES, L.G., K.W. Thomas, G.J. Stumpf, and M.D. EILTS. Enhancements to the terminal Doppler weather radar gust front algorithm. FAA Interim Report DOT/FAA/NR-91/3, 53 pp (1990). During the 1988 Operational Test and Evaluation of the FAA's Terminal Doppler Weather Radar System (TDWR), a real-time test of the gust front algorithm capabilities in a High Plains environment (Denver, CO) was accomplished. Further evaluation of the algorithm's detection capability in the Great Plains (Kansas City, KS) was conducted in 1989. Based on these operations and additional post-analysis, deficiencies in several techniques used by the TDWR gust front algorithm were noted. As a result, modifications such as feature error checking and feature checking prior to polynomial fitting were included in the algorithm. Improvements to the techniques used to vertically associate features, determine gust front orientations, and to produce gust front representations and forecasts have also been implemented. False algorithm detections, specifically those caused by the detection of radial convergence associated with the low-level jet phenomenon, are discussed. NS-040 HOLLE, R.L., AI. WATSON, R. ORTIZ, and R.E. LOPEZ. Spatial patterns of lightning, radar, echoes, and severe weather in mesoscale convective systems. Preprints, Conference on Atmospheric Electricity, Kananaskis Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, 721-726 (1990). No abstract. NS-041 Hondl, K. Estimates of helicity from VAD analysis of non-linear wind fields. Preprints, 25th Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorology Society, Boston, 568-571 (1991). No abstract. NS-042 HOWARD, K.W., and R.A MADDOX. A satellite-based climatology of warm season thunderstorms over Mexico. In CICESE Publication EBA No. 5, Ensenada, B.C., Mexico, 98-100 (1991). No abstract. NS-043 Hunter, S.M., T.J. Schuur, T.C. Marshall, and W.D. RUST. Electrical and kinematic structure of an Oklahoma mesoscale convective system. Preprints, Conference on Atmospheric Electricity, Kananskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, J52-J57 (1990). No abstract NS-044 Johns, R.H., K.W. HOWARD, and R.A. MADDOX. Conditions associated with long-lived DERECHOS - An examination of the large-scale environment. Preprints, 16th Conference on Severe Storms, Kananaskis Provincial Park, Alberta, Canada, October 22- 26, 1990. American Meteorological Society, 408-412 (1990). No abstract. NS-045 JORGENSEN, D., and J.D. DUGRANRUT. A dual-beam technique for deriving wind fields from airborne Doppler radar. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 458-461 (1991). 113 No abstract. NS-046 JORGENSEN, D. P., M. A. LeMone, and B. J.-D. Jou. Precipitation and kinematic structure of an oceanic mesoscale convective system. Part I: Convective line structure. Monthly Weather Review. 119:2608-2637 (1991). The precipitation, thermodynamic, and kinematic structure of an oceanic mesoscale convective system is studied using airborne Doppler and in-situ (flight-level) data collected by the NOAA P-3 aircraft. The system, a well-organized, stationary, north-south convective line, was located near the east coast of Taiwan. In Part I, we document the basic structure of the line with both data sets, a procedure revealing the strengths and weakness of both approaches. The Doppler data reveal that the warm, moist air feeding the line enters from the east side. Most updrafts associated with the leading edge of the convective line tilt westward below 5 km and then eastward above 5 km. This change of tilt corresponds to a change in the sign of the vertical flux of east-west momentum. To the east of the leading edge, a 10-km-wide zone of strong mesoscale descent is seen. The band is not a complete barrier to the low-level southeasterly flow, and at times and places along the line the inflowing air can move through the band with little or no upward acceleration. The minimum pressures at low levels lie east of the highest reflectivity and also underneath the tilted updraft at upper levels, in agreement with the tilt of the updraft, the buoyancy distribution, and the interaction of the updraft with the vertical shear of the horizontal wind. The Doppler data show very few convective-scale downdrafts and no low-level gust front that would organize the convection as in propagating squall lines, although lack of resolution in the psuedo-dual-Doppler data at the lowest levels may mask features with horizontal scales < 5 km. Vertical incidence Doppler observations show only a few, relatively weak, convective-scale downdrafts within the heavy rainfall region of the convective line. The in-situ data confirm that warm, moist air feeds the convective line from the east side, but they show a larger fraction of air coming into the convection from the boundary layer than do the Doppler data. They confirm that the line is not an effective barrier to the flow: some air from the east of the line, including boundary-layer air, passes through the line without joining the updrafts. Again, some weak convective-scale downdrafts are evident but a gust front was not detected. However, at low levels, a pool of low theta-E air lies 10-20 km to the west of the line, outside the dual-Doppler domain. This cool air apparently originated to the north (beneath an extensive stratiform area, but preexisting baroclinicity associated with a front may have also contributed to the cool air) and advected southward. Vertically incident Doppler data confirm the upper level downdraft zone to the east of the updraft. Above 2 km, the pressure and vertical velocity fields are consistent, with low pressure lying beneath the tilting updrafts in both data sets. Below 2 km, the in-situ data reveal a mesolow beneath the westward-tilting updraft that was not captured by the Doppler data, apparently because of contamination of the very lowest levels by ground clutter. NS-047 Keighton, S.J., H.B. Bluestein, and D.R. MACGORMAN. The evolution of a severe mesoscale convective system: Cloud-to- ground lightning location and storm structure. Monthly Weather Review 119:1533-1556 (1991). Cloud-to-ground lightning-location data are correlated with the Doppler-radar-observed structure of the evolution of a severe mesoscale convective system in Oklahoma on 23 May 1981. While many of the results are not new, this study is unique in that the evolution of electrical activity in a severe storm is compared to storm structure for most of the storm's life. The first storm formed ahead of a mesoscale low pressure area located at the intersection of a front and a dryline, and developed into a tornadic supercell in an environment of locally enhanced vertical shear. Ordinary cells subsequently formed both to the southwest and northeast of the supercell along the dryline and the front, respectively, and merged with the supercell to form a squall line having a trailing stratiform precipitation region with midlevel rear inflow. It is shown that the cloud-to-ground flash in the convective region is related to the apparent strength of the updraft. Before the storm became a supercell, the lightning strikes, which were relatively infrequent, emanated from the anvil west of the core. When the supercell was producing its first tornado, most lightning strikes occurred around the edge of the most intense core and under the anvil south of the core. As the supercell weakened, ground strikes clustered closer to the core. During the squall-line stage, most cloud-to-ground lightning strikes were found to the rear of the core of the remnants of the supercell, and in the core of the cells to the southwest, which were less mature. The overall ground-strike rate peaked during the middle portion of the squall-line phase. The area of the midlevel radar echo associated with the most intense reflectivity core was well correlated with the ground strike rate. The area of midlevel radar echo representing the weaker portion of the core, however, lagged the ground-strike rate. NS-048 LeMone, M.A., and D.P. JORGENSEN. Precipitation and kinematic structure of an oceanic mesoscale convective system. Part II: Momentum transport and generation. Monthly Weather Review. 119:2638-2653 (1991). This is the second paper of a two-part series documenting the structure of and momentum transport by a subtropical mesoscale convective system near Taiwan, using Doppler radar data and in situ data from the NOAA P-3. Part I defines the basic system structure and evolution. In Part II, the momentum transport by the system is estimated and related to system structure, and the momentum budget for a portion of the embedded convective band is evaluated. Profiles of the vertical flux of horizontal momentum are constructed from in situ data, Doppler radar data, and both combined, in a coordinate system with u normal to the line and positive eastward, since the low-level air is feeding the line from the east. Differences in the fluxes from the two sources appear to be 114 mainly due to an underestimation of the mean vertical velocity from the Doppler radar data. The discrepancy results partially from the concentration of convergence in the boundary layer - precisely where the Doppler cannot adequately sample the convergence - and partially from Doppler problems above 5 km. However, the momentum-flux profile generated from both data sources has features consistent with the structure of the line: puw is negative at lower levels, consistent with the westward tilt of most updrafts at those levels, and positive at upper levels, consistent with the updrafts' eastward tilt. This positive flux is countergradient and not consistent with previous observations, but is suggested in numerical simulations of systems in an environment similar to that for this system, with relatively low convective available potential energy (CAPE), high relative humidity aloft, and positive u shear through the depth of the system. The simulated systems have relatively weak updrafts and gust fronts, also matching this case. The flux pvw is downgradient above ~5 km and countergradient below, but is consistent with the average positive vertical velocity carrying southerlies (V>0) upward. The momentum budget reveals some behavior that differs from that of earlier systems such as that studied by Lafore et al. For example, above 7 km the momentum transport and pressure gradient reinforce to produce substantial acceleration of air exiting the band at high levels toward the front (east), although the vertical transport contributes only a small amount to the observed acceleration. The u positive acceleration at higher levels, being larger than the Doppler estimates of dU/dt at lower levels, increases the overall u shear within the convective band. Estimation of the vertical momentum-flux divergence and pressure-gradient term at low levels from the in situ data supports this result. In previously observed tropical systems, u shear was increased by convective bands only when the u shear was negative. At midlevels, the vertical transport of line-parallel wind (v) by the line acts to increase and slightly elevate the southerly jet maximum in the environmental wind profile usually seen in this region. As in previously documented systems, dV/dt decreases with time within the band. NS-049 LEWIS, J.M., and C. CRISP. Categorization of return flow in the Gulf of Mexico during the cool season. Preprints, 5th Conference on Meteorology and Oceanography of the Coastal Zone, Miami, Florida, May 6-10, 1991. American Meteorological Society, Boston, 181-183 (1991). No abstract. NS-050 LEWIS, J.M., and R.A MADDOX. The summer employment program at NOAA's National Severe Storms Laboratory: An experiment in the scientific mentorship of undergraduates. Bulletin of the American Meteorological Society 72: 1362-1371 (1991). In an effort to encourage college students to consider careers in scientific research, NOAA's National Severe Storms Laboratory has instituted a Summer Employment Program. The program is centered around a scientific mentorship experience that matches each student with a Laboratory scientist. During the nominal 12 weeks of the program, the scientist leads and directs a research project that is designed to be commensurate with the student's background. Along with the research experience, there is an educational component that encompasses both classroom work and experimentation. Additionally, students are introduced to a variety of research efforts in the Laboratory through a continuing series of guest lectures by Lab scientists. The program has operated in 1987, 1989, and 1990 and has included 17 students, 12 of whom have come from under-represented groups in our society. We report on the evolution of the program and scrutinize the results after these three years of effort. NS-051 LOPEZ, R.E., M.W. Maier, J. -A Garda-Miguel, and R.L. HOLLE. Weak positive cloud-to-ground flashes in northeastern Colorado. Preprints, 1991 International Aerospace and Ground Conference on Lightning and Static Electricity, Cocoa Beach, FL, April 16-19, 1991. NASA Conference Publication 10058, 87-1 - 87-10 (1991). No abstract. NS-052 LOPEZ, R.E., R. ORTIZ, J.A. AUGUSTINE, W.E. OTTO, and R.L. HOLLE. The progressive development of cloud-to-ground lightning in the early formative stages of a mesoscale convective complex. Preprints, 16th Conference on Severe Local Storms, Kananaskis Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, 658-662 (1990). No abstract. NS-053 LOPEZ, R.E., R. ORTIZ, W.D. OTTO, and R.L. HOLLE. The lightning activity and precipitation yield of convective cloud systems in central Florida. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 907-910 (1991). 115 No abstract. NS-054 LOPEZ, R.E., W.D. OTTO, R. ORTIZ, and R.L. HOLLE. The lightning characteristics of convective cloud systems in northeastern Colorado. Preprints, Conference on Atmospheric Electricity, Kananaskis Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, 727-731 (1990). No abstract. NS-055 LOPEZ, R.E., and R.M. Passi. Simulation experiments in site error estimation for direction finders. Journal of Geophysical Research 96:15,278-15,296 (1991). The performance of an algorithm for the recovery of site-specific errors of direction finder (DF) networks is tested under controlled simulated conditions. The simulations show that the algorithm has some inherent shortcomings for the recovery of site errors from the measured azimuth data. These limitations are fundamental to the problem of site error estimations using azimuth information. Several ways for resolving or ameliorating these basic complications are tested by means of simulations. From these it appears that for the effective implementation of the site error determination algorithm, one should design the networks with at least four DFs, improve the alignment of the antennas, and increase the gain of the DFs as much as it is compatible with other operational requirements. The use of a nonzero initial estimate of the site errors when working with data from networks of four or more DFs also improves the accuracy of the site error recovery. Even for networks of three DFs, reasonable site error corrections could be obtained if the antennas could be well aligned. NS-056 MACGORMAN, D.R., and K.E. Nielsen. Cloud-to-ground lightning in a tornadic storm on 8 May 1986. Monthly Weather Review 119:1557-1574 (1991). On 8 May 1986, the National Severe Storms Laboratory (NSSL) collected Doppler radar and lightning ground strike data on a supercell storm that produced three tornadoes, including an F3 tornado in Edmond, Oklahoma, approximately 40 km north of NSSL. The Edmond storm formed 30 km ahead of a storm complex and produced its first and most damaging tornado just as the storm complex began to overtake it from the west. In the mesocyclone that spawned the tornado, low-level cyclonic shear peaked as the first tornado dissipated and a second tornado began. As low-level cyclonic shear initially increased, negative cloud -to-ground lightning flash rates also increased, reaching a peak of 11 min'1 a few minutes after the peak in cyclonic shear. During this period lightning strike locations tended to concentrate just north of the mesocyclone, near and inside a 50-dBZ reflectivity core. As cyclonic shear decreased from its peak during and after the second tornado, negative ground flash rates also decreased, and strike locations became more scattered. Positive ground flashes began just before the storm became tornadic, and positive flash rates peaked during the tornadic stage of the storm. The evolution of cloud-to-ground lightning in the Edmond storm differed considerably from the evolution of lightning in the Binger tornadic storm of 22 May 1981 that was studied previously. In the Binger storm, ground flash rates were negatively correlated with cyclonic shear and peaked 15-20 min later than low-level shear and intracloud lightning. We suggest that the very strong mesocyclone and updraft in the Binger storm enhanced intracloud flash production and delayed ground flashes by causing the initial height of negative charge to be higher than in most storms. We also suggest that weaker updrafts and a weaker, shallower mesocyclone in the Edmond storm resulted in higher negative ground flash rates when the Edmond mesocyclone was still strong, because negative charge near the mesocyclone was at the lower heights common to most thunderstorms. NS-057 MADDOX, R.A, and K.W. HOWARD. Comment on: A study of 30 years of July and August hourly precipitation data for Omaha, Nebraska. Weather and Forecasting 5: 667-670 (1990). No abstract. NS-058 MADDOX, R.A, and D.P. JORGENSEN. Southwest area monsoon project. In CICESE, Publicacion EBA No. 5, Ensenada, B.C., Mexico, 75-79 (1991). No abstract. 116 NS-059 MATEJKA, T. Decomposition of pressure and buoyancy forces deduced from Doppler radar data in mesoscale convective systems. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 139-142 (1991). No abstract. NS-060 MATEJKA, T., and TJ. SCHUUR. The relation between vertical air motions and the precipitation band in the stratiform region of a squall line. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 501-504 (1991). No abstract. NS-061 MATEJKA, T., and R.C. Srivastava. An improved version of the extended velocity-azimuth display technique for analyzing single Doppler radar data. Journal of Atmospheric and Oceanic Technology 8:453-466 (1991). Extended velocity-azimuth display (EVAD) analysis is useful for obtaining vertical profiles of horizontal divergence, vertical air velocity, vertical hydrometer velocity, and hydrometeor terminal fall speed in widespread precipitation. The technique uses a volume of velocity data collected with a single Doppler radar. Several improvements to the previously reported EVAD technique are discussed. They include the weighting of Fourier series coefficients to reflect their estimated error, a correction for heteroscedasticity (the systematic variation of residuals) in the regression analysis, and the weighting of data from different elevation angles to compensate for the finite thicknesses of the layers in which each analysis is performed. Vertical air velocity is obtained through a variational procedure. Procedures for dealiasing the velocity data and for rejecting outliers from the dataset are summarized. Recommendations for collecting radar data for use in EVAD analysis are made. NS-062 MAZUR, V. Intracloud development of lightning strikes to aircraft. Proceedings, 1991 International Aerospace and Ground Conference on Lightning and Static Electricity, April 16-19, 1991, Cocoa Beach, FL, 3-1-3-9 (1991). The analysis of airborne electromagnetic records of seven lightning strikes to the FAA CV-580 instrumented airplane during the 1987 field campaign was aimed at revealing and interpreting processes taken place during the intracloud propagation of lightning strikes initiated on or intercepted by the airplane. It is shown that intracloud development of the strike may consist of recoil streamers, dart leader/return stroke sequences, and the secondary initiations of new discharges. These processes, with their high current pulses during strike initiation. The latter are presently considered by the technical community to be the primary lightning threat to aircraft. NS-063 MAZUR, V. Lightning threat to aircraft: Do we know all we need to know? Proceedings, 1991 International Aerospace and Ground Conference on Lightning and Static Electricity, April 16-19, 1991, Cocoa Beach, FL, 1-1-1-8 (1991). No abstract NS-064 McCaul, E.W., Jr., and D.O. BLANCHARD. A low-precipitation cumulonimbus along the dryline in Colorado. Monthly Weather Review 118:2768-2773 (1990). An unusual low-precipitation cumulonimbus that developed in northeastern Colorado is photographically documented in some detail. The storm produced at least 12 funnels, mostly at midlevels on the north side of the main updraft. The base of the cloud consisted of a lenticular "bell" that rotated cyclonically, while a couplet of counterrotating storm-scale eddies prevailed aloft. The funnels originated in a region of enhanced shear between easterly low-level flow on the north side of the bell and westerly flow aloft on the north side of a midlevel anticyclonic eddy. 117 NS-065 MEITIN, R. J., and R.A. BROWN. Dual-Doppler analysis of North Dakota thunderstorms using airborne and ground-based radars. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990 American Meteorological Society, Boston, 225-230 (1990). No abstract. NS-066 MEITIN, R J., R.A BROWN, and J.G. MEITIN. Comparison of airborne dual-Doppler and airborne/ground-based dual-Doppler analyses of North Dakota thunderstorms. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 474-477 (1991). No abstract. NS-067 Moller, A.R., C.A DOSWELL III, and R. Przybylinski. High-precipitation supercells: A conceptual model and documentation. 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, 52-57 (1990). No abstract. NS-068 Palmer, R.D., J.R. Cruz, and D.S. ZRNIC. Enhanced autoregressive moving average spectral estimation applied to the measurement of Doppler spectral width. IEEE Transactions on Geoscience and Remote Sensing 29 (3): 358-368 (1991). This paper investigates the measurement of clear air turbulence with a Doppler radar. Most methods, including ours, of estimating the intensity of turbulence are based on the Doppler spectral width, which is a measure of the variations of radial velocities within the resolution volume of the radar. Classical estimators of the spectral width use either the autocovariance or the periodogram. We propose an autoregressive moving average (ARMA) model to improve the Doppler spectral width estimates. An iterative algorithm that has its origin in system identification is used for the estimation of the ARMA parameters. By taking advantage of a priori knowledge of the correlation matrix, which arises in the derivation of the governing equations of the ARMA parameters, the ARMA spectral estimate can be improved. This improvement is shown in terms of bias and variance of the spectral width estimate. Furthermore, examples of the usefulness of this algorithm on actual experimental Doppler radar data are presented. NS-069 RABIN, R.M., LA. McMurdie, CM. Hayden, and G.S. Wade. Monitoring precipitable water and surface wind over the Gulf of Mexico from microwave and VAS satellite imagery. Weather and Forecasting 6:227-243 (1991). Spatial and temporal changes of atmospheric water vapor and surface wind speeds are investigated for a period following an intrusion of cold continental air over the Gulf of Mexico, during the Gulf of Mexico Experiment (GUFMEX) in March 1988. Microwave and infrared satellite measurements from the Special Sensor Microwave/Imager (SSM/I) instrument aboard the Defense Meteorological Satellite Project (DMSP) F8 satellite and from the GOES VISSR Atmospheric Sounder (VAS) are used to augment the sparse coverage of rawinsonde sites and surface reports in the vicinity of the Gulf of Mexico. Total precipitable water is derived from both instruments and from rawinsonde measurements at coastal locations and auxiliary sites on ships and platforms over the Gulf. Accuracies of the precipitable water derived from SSM/I and GOES are comparable, though microwave data provide more uniform coverage, when they are available, than VAS since they are relatively free from contamination by most clouds. Also, the moisture fields derived from microwave data appear to be less noisy than those derived from the infrared. To illustrate possible use of satellite data in the forecast office, moisture fields from both SSM/I and VAS are blended together into imagery, which are compared to analyses from an operational model. Surface wind speeds are also obtained from the microwave data and are compared to the surface observations. Analyses from satellite data appear to add considerable information to the moisture and wind analysis over the Gulf of Mexico and should help in forecasting moisture changes, particularly moisture return near the surrounding coastal areas. NS-070 RASMUSSEN, E.N., and S.A. Rutledge. Doppler radar observations of the two-dimensional structure of squall lines. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 497-500 (1991). No abstract. 118 NS-071 Reyes, S., and R. MADDOX (co-editors). Memorias - Proceedings, I Regional Meeting Mexico - United States on Water Balance Studies. In CICESE, Publicacion No. EBA, No. 5, Ensenada, B.C., Mexico, 102 pp. (1991). No abstract. NS-072 Reyes, S., L. Palacios, R. MADDOX, and M. DOUGLAS. Plan de operaciones: Transpote atmosferico de vapor de agua y su relacion con el campo de precipitacion de verano en el desierto Sonorense - TRAVASON VERANO 1990. CICESE Technical Report 9001, Publicacion: EBA No. 2, Ensenada, B.C., Mexico, 43 pp. (1991). No abstract. NS-073 RUST, W.D. Severe storm electricity research with a mobile laboratory and mobile ballooning. Preprints, Conference on Atmospheric Electricity, Kananskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, J31-J35 (1990). No abstract NS-074 Rutledge, S.A, E.R. Williams, WA. Peterson, and E.N. RASMUSSEN. Radar and electrical study of a tropical squall line near Darwin, Australia during DUNDEE. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 889-892 (1991). No abstract. NS-075 Schneider, J.M., and D.K. Lilly. An example of 4-D vizualization of dual Doppler data. 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991, American Meteorological Society, Boston (1991). No abstract. NS-076 SCHUUR, T.J. Airborne Doppler observations of a mesoscale convective system over the Sierra Madre Occidental Mountains of Mexico. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 482-485 (1991). No abstract. NS-077 SCHUUR, T.J., S.M HUNTER, W.D. RUST, and T.C. Marshall. Charge structure of a midlatitude mesoscale convective system. Preprints, 16th Conference on Severe Local Storms, Kananaskis Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, 663-668 (1990). No abstract. NS-078 SCHUUR, TJ., B.F. SMULL, W.D. RUST, and T.C. Marshall. Electrical and kinematic structure of the stratiform precipitation region trailing an Oklahoma squall line. Journal of the Atmospheric Sciences 48:825-842 (1991). An electric field sounding through the transition zone precipitation minimum that trailed an Oklahoma squall line on 18 June 1987 provides information about the electrical structure within a midlatitude trailing stratiform cloud. A single-Doppler radar analysis concurrent with the flight depicts a kinematic structure dominated by two mesoscale flow regimes previously identified in squall-line systems: a strong midlevel, front-to-rear flow coinciding with the stratiform cloud layer and a descending rear inflow that sloped from 6.5 km AGL at the stratiform cloud's trailing edge to 1.5 km AGL at the convective line. Electric field magnitudes as high as high as 119 113 kV m" were observed by the electric field sounding, which reveals an electric field structure comparable in magnitude and complexity to structures reported for convective cells of thunderstorms. The charge regions inferred with an approximation to Gauss' law have charge density magnitudes of 0.2-4.1 nC m"3 and vertical thickness of 130-1160 m; these values, too, are comparable to those reported for thunderstorm cells. In agreement with previous studies, an analysis of the lightning data revealed a "bipolar" cloud-to- ground lightning pattern with positive flashes being relatively more common in the stratiform region. From the analysis, we conclude that the stratiform region electrical structure may have been advected from the squall line convective cells as the in-cloud charge regions were primarily found within the front-to-rear flow. Screening layers were found at the lower and upper cloud boundaries. In situ microphysical charging also seems to be a possible source of charge in the stratiform region. We hypothesize that the radar- derived similarities of this system to those previously documented suggested that the newly-documented stratiform electrical structure might also be representative of this type of mesoscale convective system. NS-079 Setvak, M., and C.A DOSWELL III. The AVHRR Channel 3 cloud top reflectivity of convective storms. Monthly Weather Review 119 (3): 841-847 (1991). No abstract. NS-080 SMULL, B.F., D.P. JORGENSEN, and C.E. HANE. Comparison of retrieved pressure and buoyancy perturbations with in situ observations of an intense wake low in a midlatitude mesoscale convective system. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 135-138 (1991). No abstract. NS-081 STENSRUD, D.J., M.H. JAIN, K.W. HOWARD, and R.A MADDOX. Operational systems for observing the lower atmosphere: Importance of data sampling and archival procedures. Journal Atmospheric and Oceanic Technology 7(6):930-937 (1990). A brief field project was conducted during July 1988 to assess the potential for the Next Generation Weather Radar (NEXRAD), 404-MHz radar wind profilers, and digital sounding systems to monitor the low-level wind field during clear-air conditions. The low- level jet was chosen as the phenomenon of interest because it is not well-sampled nor resolved by the current upper-air network, yet it is a common feature of mesoscale convective system and severe thunderstorm environments. Data were collected under quiescent synoptic conditions during several low-level jet events using a 10-cm NEXRAD-like Doppler radar and a digital sounding system colocated in Norman, Oklahoma. These data suggest that the areal-averaged horizontal winds calculated from the Doppler radar data using the Velocity Azimuth Display (VAD) technique are comparable with the winds observed using a digital sounding system, except under weak wind conditions. However, the vertical spacing of 304 m (1000 ft) between levels of horizontal VAD calculated winds, as currently proposed for NEXRAD, may not be of sufficient resolution to document the detailed wind structure of these events. The height of the maximum wind speed of the low-level jet on all days studied was below the planned lowest observation range gate of the 404-MHz radar wind profiler, indicating that a combination of NEXRAD and profiler data might be needed to sample the important wind field structure of the lower atmosphere. Lastly, the National Weather Service rawinsonde data processing software affects the vertical resolution of the low-level wind field in operational, and therefore archived, upper-air soundings. The procedure used to calculate NWS 1000 ft winds actually damps the wind speed profile and artificially increases the height of the level of maximum wind speed associated with the low-level jet. The appropriateness of these highly smoothed 1000 ft winds for input into sophisticated mesoscale weather prediction models should be considered. NS-082 STENSRUD, D J., R.A MADDOX, and C.L. ZIEGLER. A sublimation-initiated mesoscale downdraft and its relation to rear inflow in a convective system. Monthly Weather Review 119:2124-2139 (1991). A simple, one-dimensional model is developed to examine the potential for a sublimation-initiated mesoscale downdraft to influence the dynamics of the subanvil region by advecting horizontal momentum from a high-level precipitating anvil cloud downward into the middle or lower troposphere. Model results suggest that this vertical advection can occur on a time scale of several hours or less, although it is found to be highly dependent upon the snow mixing ration within the overlying anvil cloud and lapse rates in the environment below. The study is motivated by an examination of data from a 50-MHz radar wind profiler on 24 June 1985 that suggests downward momentum advection from anvil base may have produced unbalanced flow in midlevels, owing to strong flow within the anvil and weak midlevel geostrophic winds. For this situation, we hypothesize that as the anvil cloud both dissipated and was advected horizontally away from the profiler site by the strong, upper-level winds, the downdraft weakened and an inertial oscillation began that slowly altered the midlevel airflow below the anvil cloud. This inertial oscillation appears to have persisted for hours after the mesoscale convective system dissipated, likely owing to the weak midlevel flow. While the model is not used to explain fully the 120 observed profiler wind observations, the similarity between the evolution of the simulated and observed wind fields emphasizes the importance of ice microphysics to the dynamics of regions below precipitation anvil clouds. The thermodynamic structure of the model-produced atmosphere after several hours of integration resembles the onion soundings frequently found behind convective systems in the tropics and midlatitudes. Previous observational studies show that the midlevel, near-saturated portion of the sounding is associated with mesoscale ascent. However, in the model simulations this structure is found in conjunction with mesoscale descent, suggesting that this thermodynamic signature may be associated with either midlevel ascending or descending flow fields. NS-083 Stumpf, GJ., and M.D. EILTS. Transferring the TDWR gust front detection algorithm to the WSR-88D system. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, American Meteorological Society, Boston 343-346 (1991). No abstract. NS-084 Stumpf, G J., R.H. Johnson, and B.F. SMULL. The wake low in a midlatitude mesoscale convective system having complex convective organization. Monthly Weather Review, 119: 134-158 (1991) An analysis has been carried out of the surface pressure field in a highly complex mesoscale convective system that occurred on 3-4 June 1985 during the Oklahoma-Kansas Preliminary Regional Experiment for STORM-Central (OK PRE-STORM). During its mature stage, the storm consisted of two primary intersecting convective bands approximately 200 km in length, one oriented NE-SW (to the north) and the other N-S (to the south), with a stratiform precipitation region extending to the northwest of the bands. Stratiform precipitation was weak to nonexistent in the southernmost portion of the storm. Although the organization of the storm was complex, the surface pressure field resembled that associated with simpler, quasi-linear squall systems containing trailing stratiform regions: a mesohigh existed near the convective line and a wake low was observed to the rear of the stratiform region. A strong system-relative, descending rear inflow jet was observed in the northern part of the storm near the wake low. Significantly, only the northern portion of the storm had a trailing stratiform region and it was only in that region that a wake low and a descending rear inflow jet occurred. An analysis of dual-Doppler radar data taken in the northern part of the storm indicates remarkably strong, localized subsidence at low levels within the rear inflow jet, up to 6 m s"1 on a 10 km scale at the back edge of the trailing stratiform region. The maximum sinking occurred: (a) to the rear of the highest reflectivity portion of the trailing stratiform region; (b) within the region of the strongest low-level reflectivity gradient; and (c) was coincident with the strongest surface pressure gradient (up to 2 mb (5 km)"1) ahead of the wake low center. These findings indicate that the trailing stratiform precipitation regions of mesoscale convective systems can be dynamically significant phenomena, generating rapidly descending inflow jets at their back edges and consequently producing pronounced lower-tropospheric warming, intense surface pressure gradients and strong low-level winds. NS-085 SZOKE, EJ., and J. A AUGUSTINE. A decade of tornado occurrence associated with a surface mesoscale flow feature. The Denver Cyclone. Preprints, 16th Conference on Severe Local Storms, Kananaskis Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, 554-559 (1990). No abstract. NS-086 TOLLERUD, E.I., KW. HOWARD, and X.-P. Zhong. Jet streaks and their relationship to heavy precipitation in Colorado Front Range winter storms. Preprints, First International Winter Storms Symposium, New Orleans, LA January 13-18, 1991. American Meteorological Society, Boston, 97-100 (1991). No abstract. NS-087 Trier, S.B., D.B. Parsons, and T.J. MATEJKA Observations of a subtropical cold front in a region of complex terrain. Monthly Weather Review 118:2449-2470 (1990). The passage of shallow cold fronts during the late spring and early summer months over the island of Taiwan is often accompanied by heavy rainfall and occasional flash flood episodes. Previous studies have emphasized the weak baroclinicity of these fronts and their possible modification by fluxes from the air-sea interface. In this study a cold frontal passage in the vicinity of Taiwan is analyzed using data gathered during the Taiwan Area Mesoscale Experiment (TAMEX) on 8 June 1987. At the northern extent of the TAMEX network the cold front was shallow (1-2 km deep) and moderately baroclinic with 5°-7° temperature contrasts at the 121 surface. A Doppler radar cross section of radial velocity reveals a structure similar to that of a density current at the leading edge of the shallow front. The postfrontal air mass was substantially modified by oceanic heat fluxes as it moved southward over the warm ocean waters. This led to a 60-79% decrease in the temperature contrast across the front between ocean stations at the northern and southern ends of the island, a distance of about 400 km. Frontal passages across Taiwan are also influenced by the presence of the Central Mountain Range (CMR), which has an average ridge elevation of about 2500 m, and is oriented NNE-SSW along the major axis of the island. In the case described in this paper the CMR 1) acts as a barrier to both the pre- and postfrontal flows, and 2) is influential by inducing thermally-driven diurnal circulations associated with differential heating of the sloped terrain and the nearby ocean. Terrain influences on the kinematics of the flow in the vicinity of the front are also shown to locally modify the frontal intensity. The inhomogeneous distribution of precipitation attending the frontal passage is related to strong regional variations in thermodynamic stability across the island. These variations in stability are linked to the mesoscale effects of terrain, and to the larger-scale influence of advection of an unstable tropical air mass into the region by a low-level wind maximum. NS-088 VASILOFF, S.V. The Terminal Doppler Weather Radar tornadic vortex signature detection algorithm. Preprints, 4th International Conference on Aviation Weather Systems, Paris, France, June 24-28. American Meteorological Society, J43-J48 (1991). No abstract. NS-089 VASILOFF, S.V. and A WITT. The Terminal Doppler Weather Radar tornadic vortex signature detection algorithm. FAA Interim Report DOT/FAA/NR-91/5, 19 pp. (1990). An algorithm for real-time detection of tornadoes, using single-Doppler radar data, is described. This algorithm searches for tornadic vortex signatures (TVS's) which are characterized by strong azimuthal shear in Doppler velocity fields. A TVS usually indicates that a tornado is occurring. The algorithm searches for azimuthal radial velocity differences, above a certain threshold, between adjacent gates at constant range. It then builds these "pattern vectors" into features for each scan in elevation, and finally determines the vertical correlation among features. When at least three features are vertically correlated and the lowest one is below a prescribed minimum-height threshold, a "TVS" is declared, indicating that a tornado is occurring. If the lowest feature is not below the height threshold, a "potential TVS (PTVS)" is declared, indicating that a tornado may soon occur. The TVS algorithm has been tested on five tornadoes that occurred in Colorado and Missouri. Each tornado had an associated TVS, which was detected by the algorithm. In all cases, either a PTVS or TVS preceded each tornado, resulting in a 4 minute average lead time. Evaluated on a scan- by-scan basis, the Probability Of Detection (POD) is 78%. No TVS false alarms and only 3 PTVS false alarms occurred for these 5 cases. The algorithm was also tested on two rotating microbursts with no detections occurring. NS-090 WATSON, A.I., R. L. HOLLE, R.E. LOPEZ, and J.R. Nicholson. A preliminary evaluation of short-term thunderstorm forecasting using surface winds at Kennedy Space Center. Preprints, 16th Conference on Severe Local Storms, Kananaskis Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, 413-418 (1990). No abstract. NS-091 WATSON, A.I., R. L. HOLLE, R.E. LOPEZ, and J.R. Nicholson. Surface convergence as a short-term predictor of cloud-to-ground lightning at Kennedy Space Center: A four-year summary and evaluation. Preprints, 1991 International Aerospace and Ground Conference on Lightning and Static Electricity, Cocoa Beach, FL, April 16-19, 1991. NASA Conference Publication 10058, 76-1 - 76-10 (1991). No abstract. NS-092 WATSON, A.I., R.L. HOLLE, R.E. LOPEZ, R. ORTIZ, and J.R. Nicholson. Surface wind convergence as a short-term predictor of cloud-to-ground lightning at Kennedy Space Center. Weather and Forecasting 6:49-64 (1991). Cloud-to-ground lightning is a significant forecast problem at the Kennedy Space Center (KSC) in Florida. In this study, cloud-to-ground lightning is related in time and space to surface convergence for 244 days during the convective seasons of 1985 and 1986 over a 790-km2 network at KSC. The method uses surface convergence, particularly the average over the area, to identify the potential for new, local thunderstorm growth, and it can be used to specify the likely time and location of lightning during the life 122 cycle of the convection. A threshold of 75 X 10 s"1 change in divergence is the main criterion used to define a convergence event, and a set of flashes less than 30 min apart defines a lightning event. Time intervals are found from the study to be approximately 1 h from beginning convergence to first flash, and another hour to the end of lightning. The influences of low-level winds and midlevel moisture in determining the location and intensity of convection are discussed. This is the first known dynamically-based forecast method for lightning prediction. The technique, currently in use at KSC, has been shown to be a systematic, quantitative tool for predicting lightning onset in situations where conventional analysis tools such as radar and satellite are limited. NS-093 Weygandt, S.S., K.K. Drogemeier, C.E. HANE, and C.L. ZIEGLER. Data assimilation experiments using a two-dimensional cloud model. Preprints, 16th Conference on Severe Local Storms, Kananskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, 493-398 (1990). No abstract. NS-094 WITT, A A hail core aloft detection algorithm. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, 232-235 (1990). No abstract NS-095 WITT, A, and S.P. Nelson. The use of single-Doppler radar for estimating maximum hailstone size. Journal of Applied Meteorology 30: 425-431 (1991). The relationship between a storm's divergent outflow magnitude at upper levels and maximum hailstone size was investigated by analyzing single-Doppler radar data for 49 severe hailstorms. Two different techniques were developed for use with single-Doppler radar data to estimate the magnitude of divergent outflows. The developed techniques show considerable skill at estimating the maximum hailstone size produced by a thunderstorm, with the correlation coefficients between the parameters used and maximum hailstone size being as high as 0.89. The data also show that estimates of maximum hailstone size have an 80% chance of being accurate to within ±1.4 cm. The developed techniques are computationally simple and should be useful for real-time estimation of the maximum hailstone size likely to be produced by a thunderstorm. NS-096 WOOD, V.T A preliminary examination of mesocyclone data compared with a mesocyclone model. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta Canada, October 22-26, 1990. American Meteorological Society, Boston, 442-445 (1990). No abstract. NS-097 WOOD, V.T. Objective determination of tropical cyclone tracks from land-based Doppler radar observations. Preprints, 19th Conference on Hurricanes and Tropical Meteorology, Miami, Florida, May 6-10, 1991. American Meteorological Society, Boston, 198-201 (1991). No abstract. NS-098 WOOD, V.T, and R.A BROWN. Influence of Doppler radar range on axisymmetric vortex and divergence signatures. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 197-200 (1991). No abstract. NS-099 ZIEGLER, C.L., D.R. MACGORMAN, J.E. Dye, and P.S. Ray. A model evaluation of non-inductive graupel-ice charging in the early electrification of a mountain thunderstorm. Journal of Geophysical Research 96:12,833-12,855 (1991). 123 The role of noninductive graupel-ice charge separation in the early electrification of the July 31, 1984, New Mexico mountain thunderstorm is assessed with a three-dimensional kinematic cloud model along with multiple Doppler radar and in situ measurements. Observations of the early electrification rate and the electric field distribution are consistent with modeled values that result when the noninductive mechanism works under the influence of convective motions and precipitation growth. An increase in ice particle concentrations and sizes, arising from vigorous precipitation growth, accelerates graupel-ice collision rates and hence the noninductive charging rate. Growing graupel particles experience increasing fall speed as they rise toward the top of the updraft. The resulting vertical flux convergence of graupel containing charge from previous noninductive collisions is a significant factor in the growth of the mail negative charge density. This implies that a combination of air motion, precipitation interaction, and sedimentation contributes to the rapid intensification of storm electric fields. The linear electrification phase, which begins with the cessation of convective growth, is caused by a roughly constant noninductive charging rate and by the separation of negatively charged graupel and positively charged smaller ice particles by differential sedimentation, downdrafts, and horizontal advection in vertically sheared flow. When the sign reversal temperature for noninductive charging is assumed to be -10°C, the model results are characterized by a main negative charge in middle levels and provide the best overall agreement with the in situ field measurements in the July 31 storm. For a sign reversal temperature of -21°C the model results are characterized by a mail positive charge center in middle levels, and the electric field polarity is opposite to the polarity measured at low and middle levels of the storm. The model and observational data, combined with findings of some laboratory studies, support the hypothesis that the actual reversal temperature in the July 31 storm is around -10°C. When the model includes the inductive graupel-droplet charging mechanism in addition to the noninductive mechanism, the effect of inductive charging is secondary to that of noninductive charging. The net effect of adding induction is dissipative. For example, the maximum field strength at the location of the aircraft measurements is slightly less than in the case where the noninductive mechanism acts alone. Weak charge screening layers were found to develop on the boundary of the modeled cloud. NS-100 ZRNIC, D.S. Complete polarimetric and Doppler measurements with a single receiver radar. Journal of Atmospheric and Oceanic Technology 8 (1): 159-165 (1991). The concept of the polarimetric scattering matrix applicable to hydrometeors is reviewed to indicate the total number of measurands that is possible from a radar system with two orthogonal linear polarizations. It is shown how to obtain this complete set of polarimetric measurands together with Doppler spectral moments through a single receiver by proper choice of polarization in a transmit-receive sequence pair. NS-101 ZRNIC, D.S., and N. Balakrishnan. Dependence of reflectivity factor-rainfall rate relationship on polarization. Journal of Atmospheric and Oceanic Technology 7 (5): 792-795 (1990). The reflectivity factor (Z), rainfall rate (R) relationship for weather radars that probe precipitation at low elevation angles is sensitive to polarization. It is shown how to transform a relation that is valid with one polarization (vertical, horizontal or circular) to relations that are applicable to the other two polarizations. We present errors that occur if the transformations are not applied, and an example from literature in which two seemingly different Z, R relations are equivalent, tied by the polarization transformation. NS-102 ZRNIC, D.S., N. Balakrishnan, V.N. Bringi, K. Aydin, and V. Chandrasekar. Polarimetric measurements in a severe hailstorm. 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, 666-669 (1991). No abstract. 124 PACIFIC MARINE ENVIRONMENTAL LABORATORY PM-001 AAGAARD, K., and A.T. ROACH. Arctic Ocean-Shelf exchange: Measurements in Barrow Canyon. Journal of Geophysical Research 95(C10):18,163-18,175 (1990). Two closely instrumented arrays were deployed within Barrow Canyon during 1986-1987 in an attempt to measure the outflow of dense, hypersaline plumes created during sea ice formation along the Alaskan coast. However, no hypersaline plumes were observed. Rather, we found cold, relatively fresh waters advected downcanyon by the mean flow alternating with upcanyon flow of warm and saline water upwelled onto the shelf. Upwelling was most frequent in the fall, and upcanyon speeds reached 60 cm s"1. At times the resulting onshore heat and salt fluxes were large enough to be of possible local significance, for example, to the surface heat budget. Contrary to earlier findings, the flow was only weakly correlated with the wind and the atmospheric pressure gradient. Instead, we found both upwelling and flow reversals to be coherent along the coast at sites 400 km apart, with phase differences corresponding to a typical speed of 2.3 m s-1. We suggest that the majority of these events are manifestations of shelf waves propagating eastward along the Arctic Ocean margin. PM-002 BERNARD, E.N. (editor). Tsunami Hazard: A Practical Guide for Tsunami Hazard Reduction. Reprinted from Natural Hazards 4(2,3), Kluwer Academic Publishers, Dordrecht, 326 pp. (1991). No abstract. PM-003 BERNARD, E.N. Assessment of Project THRUST: Past, present, future. Natural Hazards 4:285-292 (1991). Project THRUST (fsunami hazards deduction Utilizing Systems Technology) was a demonstration of satellite technology, used with existing tsunami warning methods, to create a low cost, reliable, local tsunami warning system. The major objectives were successfully realized at the end of the demonstration phase in September 1987. In June 1988, the Chilean Government held a workshop to assess the value of THRUST to national interests. Two recommendations came forth from the workshop: (1) the technology was sufficiently reliable and cost-effective to begin the development of an operational prototype and (2) the prototype would be used as the Chilean Tsunami Warning System. As of August 1989, the equipment was in operational use. In September 1989, major improvements were made in the satellite operations that reduced the response time from 88 to 17 sec and enlarged the broadcast area by 50%. The implications of the recent improvements in satellite technology are discussed for application to reductions in disaster impacts. PM-004 BERNARD, E.N. Meeting Reports, Fourteenth International Tsunami Symposium, Novosibirsk, USSR, 31 July-3 August 1989. Natural Hazards 4:87-97 (1991). No abstract. PM-005 BOGRAD, S.J. Sea level and bottom pressure measurements in the northern Gulf of Alaska. NOAA DR ERL PMEL-29 (PB91-184135), 58 pp. (1991). No abstract. PM-006 BOND, N.A., and MA. SHAPIRO. Polar lows over the Gulf of Alaska in conditions of reverse shear. Monthly Weather Review U9(2):55 1-572 (1991). The formation of two polar lows over the Gulf of Alaska are studied, using observations taken during the OCEAN STORMS field experiment. Synoptic-scale and mesoscale analyses were constructed using NOAA P-3 aircraft flight-level and radar data and dropwindsonde profiles, in addition to conventional data sources. The synoptic-scale analyses show that polar low development occurred in a low-level mesoscale baroclinic zone near the center of a mature, occluded synoptic-scale low pressure system. The disturbances propagated along the zone in the reverse shear sense, i.e., in the direction opposite to the thermal wind within the zone. The mesoscale analysis reveals a boundary layer jet of 38 m s_1 on the cold side of the baroclinic zone accompanying the leading polar low. Indirect evidence suggests that a 125 Sawyer-Eliassen secondary circulation was present; polar low development occurred in the region of a frontogenetical geostrophic deformation. Convective activity was not prominent during the growth phase of the polar lows, as determined from satellite imagery and radar reflectivity measurements. Extremely high ocean waves (-13 m) occurred in response to intense wind forcing on the mesoscale on a sea state preconditioned by moderate forcing on the synoptic scale. The observed synoptic-scale and mesoscale structures are compared with results from previously studied polar lows. This case appears to represent an example of polar low development due primarily to moist baroclinic processes. PM-007 CANNON, G.A., D.J. PASHINSKI, and M.R. LEMON. Middepth flow near hydrothermal venting sites on the southern Juan de Fuca Ridge. Journal of Geophysical Research 96(C7): 12.8 15-12.831 (1991). Long-term moored current measurements around the southern end of the Juan de Fuca Ridge show that flow parallels the ridge and may be intensified by its presence. The mean flow is northward on the west side and southward on the east. Thus plumes emanating from the ridge probably are advected along the ridge before flowing away from the ridge. Other topographic features may be responsible for westward or eastward turning. Along the west side of the ridge, we hypothesize a regional flow pattern with southward flow north of Axial Seamount, northward flow south of Axial, and a convergence somewhere south of Axial resulting in westward flow. Along the east side, the flow may be southward everywhere. Above the ridge crest the long-term mean flow is weaker and more variable, and it includes tidal, inertial, and a dominant broadband 4-day oscillation. This 4-day energy is maximum in the rift valley (where the inertial is least), decreases upward and away from the ridge, and is more energetic in winter. This oscillation is predominately a clockwise rotating feature which, along with the presence of inertial oscillations, suggests that it may be storm-induced from the sea surface. These observations along with those by Cannon and Pashinski (1990) suggest northward propagation. Flow variations across the ridge lasting one to a few months have mean speeds of 1-3 cm/s and are capable of transporting plumes off axis to the west or east into the northerly or southerly flows, respectively. PM-008 Chadwick, Jr., W.W., R.W. EMBLEY, and C.G. FOX. Evidence for volcanic eruption on the southern Juan de Fuca ridge between 1981 and 1987. Nature 350:416-418 (1991). The formation of new ocean crust at mid-ocean ridges is known to be a discontinuous process in both space and time, but little is known about the frequency and duration of eruptions along an active ridge segment. Here we present evidence, from Sea Beam surveys and underwater photography, for the eruption of lavas along a segment of the Juan de Fuca ridge between 1981 and 1987. Although previous studies have inferred volcanic activity on ridges in areas where recent seismicity or young lava flows have been observed, none has yet had direct evidence to date such a recent submarine eruption. The temporal coincidence between this eruptive episode and the megaplumes (huge, sudden emissions of hot mineral-laden water) observed over this part of the ridge in 1986 and 1987 supports previous suggestions that megaplumes are caused by sea-floor spreading events. PM-009 Coale, K.H., C.S. Chin, G.J. MASSOTH, K.S. Johnson, and E.T. BAKER. In situ chemical mapping of dissolved iron and manganese in hydrothermal plumes. Nature 352:325-328 (1991). Hydrothermal vents along mid-ocean ridges are an important source of elements such as lithium, silicon, manganese and iron to the world's oceans. The venting produces both episodic and steady-state hydrothermal plumes with unique thermochemical signatures in the mid-water column. The particulate phases in these plumes (predominantly iron oxides and hydroxides) also scavenge phosphorus, vanadium, arsenic, lead, polonium and several rare-earth elements from sea water. Thus, on a global scale, hydrothermal plumes are both a source for some elements and a sink for others. Ultimately, the particulate metals precipitated from plumes form extensive regions of metalliferous sediments over the crests and flanks of mid-ocean ridges. Although the metalliferous sediment coverage is vast and well documented, only a tiny fraction of the vents responsible for these sediments have been located. To date, both the number and location of hydrothermal vents and the detailed distribution of chemical constituents within the resultant plumes are poorly understood because of under-sampling of the mid-ocean ridges and the overlying waters. Here we present the results of high-resolution mapping of the chemical and thermal characteristics of hydrothermal plumes in near real time using a novel submersible chemical analyser (Scanner) and a conductivity/temperature/depth/transmissometer instrument package (CTDT). We show that the kinetics of iron oxidation in the plume can be used to constrain estimates of the plume's age, and that variation in the ratio of manganese content to excess heat can be explained by the mixing of several different vent fluids. PM-010 COKELET, E.D., R.J. Stewart, and C.C. Ebbesmeyer. Concentrations and ages of conservative pollutants in Puget Sound. Proceedings, Puget Sound Research '91, Seattle, WA, January 4-5, 1991, Puget Sound Water Quality Authority, 99-108 (1991). No abstract. 126 PM-011 Cowen, J.P., G J. MASSOTH, and R.A. FEELY. Scavenging rates of dissolved manganese in a hydrothermal vent plume. Deep-Sea Research 37(10A): 1619-1637 (1990). The biogeochemical scavenging of dissolved manganese (Mn) from hydrothermal plumes was investigated using radiotracer (34Mn) techniques. The measured scavenging rate constant, kv was lowest in the buoyant plume (<0.2 y"1), increasing to -2 y"1 in the non-buoyant plume at distances of 20 km from the ridge valley axis. The direct biological contribution to the dissolved Mn scavenging rate (i.e., the fraction suppressed by the addition of a metabolic poison) also increased over the same distances, being minor or absent at plume depths in the proximal plume, yet the major component at distal plume stations. These and other data suggest that the capacity for scavenging dissolved Mn onto particles evolves with increasing age of the plume, suggestive of a microbial response to changing conditions within the plume. Estimated maximum scavenging rates of dissolved Mn onto particles (rtDMn = kj [DMn]) were noted at plume depths for all stations, a function of very high dissolved Mn concentrations in the case of the buoyant plume and proximal non-buoyant plume. J?DMn values, integrated over plume depths, ranged from 3.4 to 1.7 mM m-2 y-1 for the non-buoyant plume at on-axis and off-axis stations, respectively. The application of the data to the dispersal of hydrothermal constituents and to plume aging is discussed. PM-012 CUDABACK, C.N., A.J. PAULSON, and J.W. LAVELLE. A modeling study of the vertical distribution and transport of manganese in Puget Sound. NOAA TM ERL PMEL-93 (NTIS not yet available), 21 pp. (1991). A one-dimensional vertical distribution and transport model tracing the fate of Mn in dissolved and fine particulate forms and Mn associated with rapidly settling aggregates is developed and results are compared with measurements. Those measurements take the form of vertical profiles of dissolved and particulate Mn concentrations measured in the water column at one station in central Puget Sound. The model provides a framework relating sources, sinks, distributions and fluxes of Mn in a quantitative manner. The model accurately reproduces the vertical distributions of dissolved and particulate Mn, but shows excessive vertical flux of Mn. The model suggests that particles in each of two size classes should carry nearly the same loading of Mn, but measurements show significantly less Mn loading on macroaggregates than on fine particles. Mn budgets from model results allow comparison of major Mn fluxes in Puget Sound. The flux of Mn into the central main basin in particulate form is about half the diffusive flux of dissolved Mn from the bottom. A significant fraction of the riverine flux of particulate Mn is adverted out of Puget Sound in dissolved form. PM-013 CURL, JR., H.C., and A.J. PAULSON. The biogeochemistry of oxygen and nutrients in Hood Canal. Proceedings, Puget Sound Research '91, Seattle, WA, January 4-5, 1991, Puget Sound Water Quality Authority, 109-105 (1991). Although organic loadings to the nation's estuaries have declined as result of improved waste treatment practices, loadings of nutrients (e.g., phosphates, nitrogen compounds) continue to increase. Increased nutrients are responsible for, or have been implicated in, hypoxic/anoxic events, red and brown tides, and altered food chains. Hood Canal offers an ideal situation in which to examine some of the fundamental processes in nutrient dynamics because of its circulation features and nutrients sources. The chemical oceanography of Hood Canal is reviewed, based on data spanning nearly 40 years. Hood Canal is a somewhat smaller, simplified version of Puget Sound proper, with a vigorous circulation. Intrusions of high density water via Admiralty Inlet and several sources of fresh water produce strong near- surface stratification within the euphotic zone throughout much of the year. Most striking is the occurrence of a persistent subsurface oxygen minimum layer typified by in situ nitrification. Increased organic and nutrient loadings to Hood Canal could easily lead to periods of extensive hypoxia and anoxia as well as other problems. PM-014 EBLE, M.C., and F.I. GONZALEZ. Deep-ocean bottom pressure measurements in the northeast Pacific. Journal of Atmospheric and Oceanic Technology 8(2):221-233 (1991). Pressure transducers with quartz-crystal resonators are being used to measure deep-ocean bottom pressure in the northeast Pacific as part of a long-term monitoring program. In principle, instrument sensitivity is less than 1 mm for sea-level oscillations of periods greater than a few minutes; in practice, however, system resolution is limited by long-term sensor drift and background noise. Data are digitally recorded at a rate of 64 samples per hour but selectable intervals ranging from 4 to 128 samples per hour are possible. The field program has focused on the maintenance of five permanent stations in the northeast Pacific since 1986. During this time, phenomena over a wide range of time scales have been recorded, including tides and the seismic surface waves and tsunamis generated by three earthquakes in the Alaskan Bight. PM-015 EMBLEY, R.W., W. Chadwick, M.R. Perfit, and E.T. BAKER. Geology of the northern Cleft segment, Juan de Fuca Ridge: Recent lava flows, seafloor spreading, and the formation of megaplumes. Geology 19:771-775 (1991). 127 Geologic mapping and lava sampling were earned out after the discovery of large bursts of hydrothermal fluids (megaplumes) over the southern Juan de Fuca Ridge in 1986 and 1987. Our investigations of the northernmost section of the Cleft segment have discovered: (1) semicontinuous low-temperature venting and one major high-temperature vent site along 17 km of the neovolcanic zone and (2) very glassy, lightly sedimented sheet flows and pillow mounds superimposed on older terrain over about 24 km along the northernmost part. The pillow mounds are documented to have erupted between 1981 and 1987. The occurrence of the megaplumes during this same time period strengthens the hypothesis that megaplumes are caused by sea-floor extension events. Although the basalts from the entire length of the neovolcanic zone of the Cleft segment appear to have been derived from the same mantle source, a systematic northward increase in Mg number along the segment within the neovolcanic zone indicates less shallow-level differentiation to the north, possibly related to the development of new magma chambers during the recent phase of sea-floor spreading that has occurred there. PM-016 EMBLEY, R.W., S.L. Eittreim, CH. McHugh, W.R. Normark, G.H. Rau, B. Hecker, A.E. DeBevoise, H.G. Greene, W.B.F. Ryan, C. Harrold, and C. Baxter. Geological setting of chemosynthetic communities in the Monterey Fan Valley system. Deep-Sea Research 37(11): 1651-1667 (1990). Alvin dives and camera tows within the "meander area" of the Monterey and Ascension Fan Valleys have located nine chemosynthetic communities over depths ranging from 3000 to 3600 m over a distance of 55 km. Most of the observed communities consist largely of Calyptogena phaseoliformis, but Solemya (species unknown) and a pogonophoran (genus Polybrachia), have also been identified. The 613C values (-35.0 to -33.6 per mil) and the presence of APS reductase and ATP sulfurylase in the C. phaseoliformis tissue is consistent with sulfur chemoautotrophy. Two reduced organic matter sources for the H2S are proposed: (1) older beds exposed by the deep erosion (up to 400 m) of the fan valleys and (2) concentrations of anaerobically decomposed organic matter buried in the valley floor. PM-017 FEELY, R.A., J.H. Trefry, G.J. MASSOTH, and S. Metz. A comparison of the scavenging of phosphorus and arsenic from seawater by hydrothermal iron oxyhydroxides in the Atlantic and Pacific Oceans. Deep-Sea Research 38(6):617-623 (1991). Studies of hydrothermal plumes on the Juan de Fuca Ridge and the Mid-Atlantic Ridge indicate that newly-formed Fe oxyhydroxides, formed as a consequence of hydrothermal venting, readily scavenge P and As from seawater in proportion to the dissolved concentrations of these elements. The Fe content of the suspended matter decreases from -40% near the vents to <5% in ambient seawater, with particulate P and As concentrations correlating well with Fe throughout this range. The P/Fe ratio in the oxyhydroxide phase is about 1.8 times higher in Juan de Fuca Ridge samples relative to samples from the Mid-Atlantic Ridge. In contrast, the As/Fe ratio in the oxyhydroxide phase is about the same for both regions. Calculated distribution coefficients for P and As in the Fe oxyhydroxide phase show remarkable agreement between the Atlantic and Pacific Oceans. Thus, inter-ocean variations in the element/Fe ratios are a function of dissolved concentrations of the chemical species. PM-018 FREJTAG, H.P., M.J. MCPHADEN, C.S. COHO, and A.J. SHEPHERD. Equatorial wind, current and temperature data: 1086W to 140°W; April 1983 to October 1987. NOAA DR ERL PMEL-35 (NTIS not yet available), 116 pp. (1991). No abstract. PM-019 Frick, W.E., C.A Bodeen, D.J. Baumgartner, and C.G. FOX. Empirical energy transfer function for dynamically collapsing plumes. Proceedings, International Conference on Physical Modeling of Transport and Dispersion, E.E. Adams and G.E. Hecker (eds.), Massachusetts Institute of Technology, August 7-10, 1990, 2A.25-2A.30 (1991). Dynamic collapse is recognized as one of several processes that determine far-field plume behavior; therefore, models that use the round plume assumption become invalid there. To overcome this limitation, a conservation of energy approach is used to model collapsing plumes in stratified ambient flows. A common time scale governing rise and collapse is found that further proves the importance of collapse. PM-020 Giese, B.S., and D.E. HARRISON. Eastern equatorial Pacific response to three composite westerly wind types. Journal of Geophysical Research 96(Sup):3239-3248 (1991). It has been suggested recently that episodes of westerly wind near the international date line in the western Pacific tend to fall into one of four types. Three of the types have enough equatorial zonal wind variation to be able to induce an eastern Pacific response by forcing equatorial waves. In this note we examine the central and eastern Pacific waveguide response to idealized representations of these three types of westerly wind episodes, using a combination of linear theory and results from an ocean general circulation model. The idealized westerly 128 wind types are the C type (maximum anomalies centered on the equator), the N type (maximum anomalies just north of the equator), and the S type (maximum anomalies just south of the equator). The composite C-type event excites equatorially trapped Kelvin pulses that alter sea surface temperature in the central and eastern Pacific. Warm anomalies caused by the C-type episode have approximately equal contributions from a zonal advection of heat by the Kelvin pulses and a meridional advection of heat by an altered instability wave field. Because the center of forcing of the S-type event is displaced off of the equator, the Kelvin pulses excited by the S-type episode have smaller amplitude than those of the C-type episode, even though the maximum wind anomaly is the same in the two cases. The S-type anomaly also excites weak Rossby-gravity waves that can propagate into the eastern Pacific. Because the Rossby-gravity waves are dispersive, their amplitude diminishes as the waves propagate into the eastern Pacific. The N-type episode, as observed in winds from the western tropical Pacific, is much weaker and of shorter duration than the C and S types, and therefore excites only a very weak eastern Pacific response. Although all types of westerly wind excite a local western Pacific response, only the C- and S-type events excite a significant eastern Pacific response. PM-021 GONZALEZ, F.I., and Ye.E. Kulikov. On frequency modulation observed in two PacTOP deep ocean tsunami records. Proceedings, 2nd UJNR Workshop, Honolulu, HI, 5-6 November 1990, A.M. Brennan and J.F. Lander (eds.). NGDC Geophysical Record Document No. 24, 27-29 (1990). Deep ocean tsunami waveforms measured by PacTOP bottom pressure recorders on 30 November 1987 and 6 March 1988 display amplitude and frequency modulation. An analysis of the temporal evolution of spectral energy suggests that frequency dispersion as predicted by classical linear wave theory is an important process governing the evolution of these waveforms. PM-022 GONZALEZ, F.I., C.L. Mader, M.C. EBLE, and E.N. BERNARD. The 1987-88 Alaskan Bight Tsunamis: Deep ocean data and model comparisons. Natural Hazards 4:119-139 (1991). Excellent deep ocean records have been obtained of two tsunamis recently generated in the Alaskan Bight on 30 November 1987 and 6 March 1988, providing the best available data set to date for comparison with tsunami generation/propagation models. Simulations have been performed with SWAN, a nonlinear shallow water numerical model, using source terms estimated by a seafloor deformation model based on the rectangular fault plane formalism. The tsunami waveform obtained from the model is quite sensitive to the specific source assumed. Significant differences were found between the computations and observations of the 30 November 1987 tsunami, suggesting inadequate knowledge of the source characteristics. Fair agreement was found between the data and the model for the first few waves of the 6 March 1988 tsunami. Model estimates of the seismic moment and total slip along the fault plane are also in fair agreement with those derived from the published Harvard centroid solution for the 6 March 1988 event, implying that the computed seafloor deformation does bear some similarity to the actual source. PM-023 HARRISON, D.E. Equatorial sea surface temperature sensitivity to net surface heat flux: Some ocean circulation model results. Journal of Climate 4(5):539-549 (1991). Several primitive-equation ocean general circulation model experiments have been carried out in order to explore the sensitivity of equatorial sea surface temperature (SST) results to uncertainty in the net surface heat flux (Q) imposed at the surface. Both climatological seasonal cycle experiments and hindcasts of the 1982/83 ENSO event are considered. It is found that regions of light winds, which typically reach values of SST in excess of 31°C using this ocean model and past Qparameterizations, attain more realistic SST values of 29°-30°C when Q is reduced by as little as 10 W m"2. Sensitivity in this regime is about 0.1-0.2°C (W m"2)"1 for low-frequency SST changes. In regions of easterly winds with their associated upwelling, horizontal advection, and stronger mixing, changes of Q in excess of 50 W m~2 produce SST changes typically of 0.7°C, for a sensitivity of about 0.02°C (W m"2)"1. These results apply equally well to the ENSO hindcasts and the seasonal cycle studies. The reasons for the large variation in sensitivity and the very large sensitivity under light winds are described. To the extent that these results are representative of oceanic conditions, very accurate Q information will be required for studies of the low-frequency variability of SST in light wind regions like the western Pacific; much less accurate fluxes appear needed for studies of comparable variability in upwelling regions. PM-024 HARRISON, D.E. Tropical ocean circulation models: Sensitivity to surface fluxes. Proceedings, International TOGA Scientific Conference, WCRP-43, October 1990 (WMPm> #379), 169-177 (1990). No abstract. 129 PM-025 HARRISON, D.E., and B.S. Giese. Episodes of surface westerly winds as observed from islands in the western tropical Pacific. Journal of Geophysical Research 96(Sup):3221-3237 (1991). We describe the characteristics of surface westerly wind episodes in the tropical Pacific between mid-1957 and 1980, as they can be determined from a collection of daily average wind records from islands. Several types of frequency of occurrence and duration statistics are presented; events in which the maximum westerly anomalies exceed 7 m s-1 are not common, but are prominent in the records. There is strong seasonal and geographical variation in frequency of occurrence. Four types of westerly episodes are found; we call them types N, C, S, or FS, according to whether the maximum westerly wind is found north of, centered on, south of, or "far south" of the equator near the international date line. Sixteen, 45, 47, and 47 events of type N, C, S, and FS are identified, respectively. The strongest westerly winds are associated with type C and S events; maximum daily average values can exceed 20 m s-1. Only type C and S events are found to have substantial equatorial zonal wind anomalies. Several examples of type C and S events are presented. Composite events of each type have been computed, and their characteristics are described. In order to explore relationships between equatorial westerly events and cyclones, all of the named tropical cyclones within a region encompassing the near-date line islands have been identified; various statistics are presented, but no absolute relationships have been identified. The similarity between the composite type C and S anomaly patterns and patterns of the El Nino-Southern Oscillation monthly mean zonal wind anomaly previously documented in the literature is striking; evidently, the westerly events often dominate in the monthly average anomaly. PM-026 HAYES, S.P. (editor). Equatorial Pacific Ocean Climate Studies (EPOCS) Progress Report, June 1991. NOAA Special Report ERL PMEL (NTIS not yet available), 94 pp. (1991). No abstract. PM-027 HAYES, S.P., P. Chang, and M.J. MCPHADEN. Variability of sea surface temperature in the eastern equatorial Pacific during 1986-1988. Journal of Geophysical Research 96(C6): 10,553-10,566 (1991). Time series of surface wind and upper ocean temperature and velocity, obtained from equatorial moorings along 110°W, are used to assess the importance of various oceanic and atmospheric processes in the variation of the mixed layer temperature for the period January 1986 to June 1988. This period coincides with the onset and development of the 1986-1987 El Nino-Southern Oscillation warm event and a subsequent cold event in 1988. Results of the temperature equation analyses indicate that seasonal and interannual variability of sea surface temperature (SST) in the eastern Pacific cannot be accounted for by observed surface heat flux; oceanic processes play an important role in the heating of the surface water. Although no single process dominated SST change, the most important processes in the mean balance were the net incoming surface heat flux, the penetrative solar radiation, and the vertical turbulent flux out the bottom of the mixed layer. The mean vertical entrainment could not be estimated with the available data. On the seasonal time scales, both the vertical turbulent heat flux and the vertical entrainment variations were well correlated with SST change. Zonal advection was a significant contribution to the heat flux variability, but its fluctuations were poorly correlated with the mixed layer heating. In particular, it was found that zonal advective heat flux tended to be out of phase with the spring warming. At higher frequencies, little zonal advective heat was found to be associated with the passage of a Kelvin event in January 1987. Surprisingly, meridional heat advection appeared more important than the zonal heat advection in modifying the local SST as this event passed the mooring location. PM-028 HAYES, S.P., L.J. MANGUM, M. McPHADEN, and J. Picaut. Thermal structure variability along 1658E. Air-Sea Interaction in Tropical Western Pacific, Proceedings, US-PRC International TOGA Symposium, Beijing, 1988, China Ocean Press, 101-111 (1990). No abstract. PM-029 HAYES, S.P., L.J. MANGUM, J. Picaut, A. Sumi, and K. Takeuchi. TOGA-TAO: A moored array for real-time measurements in the tropical Pacific Ocean. Bulletin of the American Meteorological Society 72(3):339-347 (1991). The importance of the El Nino-Southern Oscillation phenomenon in year-to-year fluctuations of the global climate has led to efforts to improve the real-time ocean observing system in the tropical Pacific. One element of this improved system is the TOGA-TAO (Tropical Atmosphere-Ocean) Array of wind and upper ocean thermistor chain moorings. This array, the result of an international effort, has already provided the rudiments of a basin-wide, real-time observing system and plans call for a major enhancement during the second half of the TOGA decade. The development of the TAO array is discussed, recent results from the pilot measurements are described, and plans for the expanded array are presented. 130 PM-030 HAYES, S.P., L.J. MANGUM, and O.F. Steffin. The Tropical Atmosphere Ocean Array. Proceedings, Oceans '91, Honolulu, HI, October 1-3, Ocean Technologies and Opportunities in the Pacific for the 90*s, IEEE 91CH3063-5, 835-838 (1991). The focus of the international Tropical Ocean and Global Atmosphere (TOGA) program has been the investigation of the oceanic and atmospheric dynamics relating to the El Nino phase of the Southern Oscillation phenomenon in the equatorial Pacific Ocean and its importance in the year-to-year variability of global climate. As part of the TOGA program, efforts have been made to enhance the real-time ocean observing system in the tropical Pacific Ocean. One element of this improved system is the TOGA-Tropical Atmosphere Ocean (TAO) array of wind and upper ocean thermistor chain moorings. Measurements from these moorings include surface parameters (wind, air and sea surface temperature) as well as subsurface temperatures down to a depth of 500 meters. These data are transmitted to shore in real- time using the ARGOS system on NOAA's polar orbiting satellites, processed by Service ARGOS, and placed on the Global Telecommunications System. Post recovery processing and analysis of the data is performed at NOAA's Pacific Marine Environmental Laboratory, Seattle, Washington. This array and its planned expansion is the result of international collaboration with scientists from France, Japan, Korea and USA. The TAO array, its development, and plans for an expanded array are discussed. PM-031 Hebert, D., J.N. Mourn, C.A. Paulson, D.R. Caldwell, T.K. Chereskin, and M.J. MCPHADEN. The role of turbulent stress divergence in the equatorial Pacific zonal momentum balance. Journal of Geophysical Research 96(C4):7127-7136 (1991). From a comprehensive set of upper ocean measurements made during a moderate El Nino in boreal spring 1987, we reassess the role of turbulence in transporting momentum vertically at the equator. An examination of the terms in the vertically integrated zonal momentum equations indicates that on short time scales the zonal pressure gradient is not balanced by the surface wind stress despite an apparent balance of these terms on longer (seasonal) time scales. The vertical redistribution of zonal momentum is complex. The strength of the wind determines both the magnitude and, likely, the mechanisms of momentum transport between the surface and the core of the undercurrent. During low wind conditions in April 1987 the turbulent stress divergence was significantly different in magnitude and vertical structure from that found during strong winds in November 1984. In November 1984 the turbulent stress divergence was much too large above 40 m to balance the residual term in the zonal momentum budget of Bryden and Brady (1984, 1989) and decayed exponentially with depth from the wind stress value at the surface. In April 1987 the turbulent stress divergence was smaller than that required by Bryden and Brady and decayed linearly from the surface wind stress. For a proper comparison with Bryden and Brady's zonal momentum balance, it is necessary to determine the annual average turbulent stress divergence. PM-032 Hinckley, S., K.M. Bailey, S.J. Picquelle, J.D. SCHUMACHER, and P.J. STABENO. Transport, distribution, and abundance of larval and juvenile walleye pollock (Theragra chalcogramma) in the western Gulf of Alaska. Canadian Journal of Fisheries and Aquatic Sciences 48(l):91-98 (1991). The spawning distribution of walleye pollock {Theragra chalcogramma) and subsequent southwesterly drift of eggs, larvae, and juveniles were investigated in Shelikof Strait, March-September 1987. In mid-March, a hydroacoustics survey found that spawning adults were concentrated in the deeper parts of Shelikof Strait, as were eggs collected in this area during an ichthyoplankton survey about 1 mo later. In May, a concentration of young larvae was found 100-150 km to the southwest of the spawning area. In late June and early July, the center of distribution of late larval and early juvenile walleye pollock was further to the southwest, between the Shumagin and Semidi Islands. By August and September, juveniles were mostly distributed downstream of the Shumagin Islands. The rate of drift of eggs and larvae through June was estimated at 4-6 cm/s. The trajectories of satellite-tracked buoys deployed in the region of greatest egg abundance revealed similar patterns to those of the early life stages of walleye pollock. These observations demonstrate that transport is an important factor determining the distribution of pollock larvae in downstream coastal nursery areas. PM-033 Ingraham, Jr., W.J., R.K. REED, J.D. SCHUMACHER, and S.A. MACKLIN. Circulation variability in the Gulf of Alaska. Eos, Transactions of the American Geophysical Union 72:257-264 (1991). We have recently found a connection between the effects of large-scale atmospheric forcing over the Gulf of Alaska and deep-water properties (temperature and salinity) below the southern sill depth (-200 m) in Shelikof Strait, through studies under the Fisheries Oceanography Coordinated Investigations (FOCI) program. Started in 1984 by the National Oceanic and Atmospheric Administration, most FOCI research has been conducted in Shelikof Strait, Alaska, a large estuarine-like system located between Kodiak Island and the Alaska Peninsula, where vast numbers of walleye pollock spawn each spring. 131 PM-034 JOHNSON, J.E., and W. Mitchell. Structure of the marine boundary layer over the Pacific Ocean during the RJTS 88 and RJTS 89 cruises. NOAA DR ERL PMEL-27 (PB91-176412), 105 pp. (1991). No abstract. PM-035 LAVELLE, J.W., E.D. COKELET, and G.A. CANNON. A model study of density intrusions into and circulation within a deep, silled estuary: Puget Sound. Journal of Geophysical Research 96(C9): 16,779-16,800 (1991). A laterally averaged hydrodynamical model is used to investigate episodic intrusions of denser, more oceanic water across the shallow double-silled entrance of Puget Sound and the resulting circulation within the interior deep basin. Tidal, freshwater discharge and wind effects are also encompassed in model results. Model simulations were made of the 4-month period from December 1983 through March 1984. During that period, hourly measurements of currents and salinity were made at the estuary entrance and on four moorings in the interior basin. The first 60 days of salinity data were used with the model to choose rates of vertical turbulent mixing and the lag times between fresh water appearance at river gauges and its arrival in the main basin of the sound. Comparison of model results with the full 120 days of salinity and velocity data shows that the model incorporates the important circulation features of this estuary. The model was then used to study intrusions and mixing in the sill region. The model identifies these factors as controls on the occurrence and strength of intrusions: the trans-sill salinity gradient, the intensity of tidal stirring and mixing over the sills, the supply of fresher surface water resulting from river runoff, and the winds. Time series of salinities in the interior basin show local maxima following local maxima in the trans-sill salinity difference. Vertical transport in the sill region at both tidal and subtidal time scales is dominated by advection rather than diffusion. Though much of the vertical exchange occurs over the shallower sill, a depth depression between the two entrance sills appears to be the site of significant overturning. Downwelling of surface water occurs on the landward side of both sills. Substantial freshening of the interior basin occurs during the winter months because river discharges are large and are stirred downward in the sill region to be entrained into landward bottom flows. Extraordinarily large river discharges can suppress the effect of large trans-sill salinity differences with the effect of weakening potential intrusions. Winds can indirectly influence intrusions by longitudinally positioning fresher, river-influenced surface water in the sill region. Winds can directly influence intrusions via bottom compensation flows in Admiralty Inlet, with northward winds encouraging intrusions, and by changing salinities at the entrance to the sound, and thus the trans-sill salinity gradient. PM-036 LAVELLE, J.W., C.N. CUDABACK, A.J. PAULSON, and J.W. Murray. A rate for the scavenging of fine particles by macroaggregates in a deep estuary. Journal of Geophysical Research 96(Cl):783-790 (1991). 234Th activity profiles in Puget Sound have been studied using a model that incorporates reversible exchanges between dissolved, fine particulate, and macroaggregate Th reservoirs. Macroaggregate settling is made responsible for the downward flux of Th and the vertical gradients of activity in measured profiles. Least squares fits of model to data yield rates/time scales for the exchange processes involved. Fine-particle scavenging by macroaggregates is found to occur with a time scale of 4-6 days over a large range of macroaggregate settling speeds, ws. MacToaggregate-disaggregation time scales are 1-4 days when ws is 100 m/d. Rates of sorption and remobilization characterizing the exchange between dissolved and fine-particulate forms of the isotope cannot be individually identified from these data, but acceptable model values include those measured in the laboratory. Rates of sorption that depend on particulate concentrations which increase to the sea floor result in profiles of dissolved Th having above-bottom maxima. Based on inferred exchange rates, the residence time for fine particles introduced at the surface of this deep (-200 m) estuary is estimated to be 11-16 days when ws = 100 m/d. PM-037 LAWRENCE, L.A., J. GRAY, and D.M. Blood. Fisheries-Oceanography Coordinated Investigations (FOCI) Field Operations— 1987. NOAA DR ERL PMEL-28 (PB91-176230), 61 pp. (1991). No abstract. PM-038 MACKLIN, S.A., N.A. BOND, and J.P. Walker. Structure of a low-level jet over lower Cook Inlet, Alaska. Monthly Weather Review 118(12):2568-2578 (1990). During February 1982 a NOAA research airo-aft investigated a cold, low-level jet blowing from a gap between mountain ranges on the west side of Cook Inlet, Alaska. The jet blew 200 km southeastward across Cook Inlet between the Kenai Peninsula and the Kodiak archipelago, passing into the Gulf of Alaska where it merged with the large-scale marine wind field. Measurement commenced -35 km downstream of the seaward end of the gap. The jet's internal boundary layer accelerated by 5% and grew 20% in depth for -50 km; thereafter, wind speed and boundary-layer depth were nearly constant for the next 100 km. The strongest winds (>20 m s"1 at a height of 80 m) were observed on the south side of the jet's thermal axis and 90 km downstream from the coast. Budget analyses reveal that the down- 132 gradient acceleration within the jet was principally opposed by surface friction, and the cold air advection was balanced by a strong upward- directed sensible heat flux from Cook Inlet and entrainment of warmer air from aloft. PM-039 MANGUM, L., J. LYNCH, K. MCTAGGART, L. STRATTON, AND S. HAYES. CTD/02 data measurements collected on TEW (Transport of Equatorial Waters) June-August 1987. NOAA DR ERL PMEL-33 (PB91-224527), 375 pp. (1991). Summaries of Neil Brown Instrument System (NBIS) CTD/02 measurements recorded on the TEW (Transports of Equatorial Waters) cruises during 1987, a description of the acquisition and processing systems, and a discussion of calibration techniques are presented. The major portion of these data was collected from 1508W to 150°E in the latitude range of 12°S-15°S. Additional casts collected across the Samoan Passage, in the Coral Sea Basin, across the Solomon Sea, and in the Pacific Basin along longitude 165°E between 5°S and 8°N are also presented. Station locations, meteorological conditions, and profiles of potential temperature, salinity, oe and oxygen are shown for each cast. In addition, potential temperature-salinity diagrams for each cast and section plots of oceanographic variables are given. PM-040 McPHADEN, M.J., D.V. HANSEN, and P.L. Richardson. A comparison of ship drift, drifting buoy, and current meter mooring velocities in the Pacific South Equatorial Current. Journal of Geophysical Research 96(C1):775-781 (1991). In this note we compare mean seasonal cycles of zonal and meridional velocity in the Pacific South Equatorial Current based on current meter mooring data, drifting buoy data, and ship drift data. Monthly averages of ship drift and drifting buoy data were computed over 2° latitude by 10° longitude rectangles centered at the positions of multiyear current meter moorings near 0°, 110°W, and 0°, 140° W. All three representations of the flow field show the basic character of the annual mean and its variations, provided that the sampling characteristics associated with each measurement technique are taken into account. In particular we find that more than 15 days of drifter data (regardless of year) are required on a 2s latitude by 10° longitude basis to produce monthly mean estimates that agree with moored estimates to within about 5-10 cm s"1 rms. We also infer that windage affects climatological monthly mean ship drift velocities, although uncertainties in the data limit a precise determination of the windage magnitude. An upper bound appears to be about 3% of the surface wind speed, though the actual effect of windage may be considerably smaller. PM-041 McPHADEN, M.J., and S.P. HAYES. Moored velocity, temperature and wind measurements in the equatorial Pacific Ocean: A review of scientific results, 1985-1990. Proceedings, International TOGA Scientific Conference, Honolulu, HI, 16-20 July 1990. Report WCRP-43, World Meteorological Organization, Geneva, Switzerland, 59-69 (1990). In this paper we review the technical and scientific evolution of moored measurement programs during the first half of the Tropical Ocean-Global Atmosphere (TOGA) program. The emphasis will be on the Pacific where the TOGA observing array is most developed; and on the upper ocean which is most relevant in the discussion of air-sea interaction. The review is based on publications which have appeared between the start of TOGA in 1985 and the present. Among these are 65 papers that have utilized TOGA (and in some cases pre-TOGA) mooring data in the refereed literature, plus numerous contributions that have appeared in meeting proceedings, newsletters and technical reports. PM-042 McPHADEN, M.J., and S.P. HAYES. On the variability of winds, sea surface temperature, and surface layer heat content in the western equatorial Pacific. Journal of Geophysical Research 96(Sup):3331-3342 (1991). In this study we examine the surface layer heat balance using wind, current, and temperature data from equatorial moorings along 165°E. The analysis focuses primarily on daily to monthly time scale variations during the 1986-1987 El Nino/Southern Oscillation event. The period is one of high mean sea surface temperatures (229°C) and frequent outbreaks of westerly winds. We infer that evaporative cooling related to wind speed variations accounts for a significant fraction of the observed sea surface temperature (SST) and upper ocean heat content variability. This evaporative heat flux converges nonlinearly in the surface layer, giving rise to larger temperature variations in the upper 10 m than below. Other processes examined (wind-forced vertical advection and entrainment, lateral advection) were negligible or of secondary importance relative to evaporative cooling. A large fraction of the SST and surface layer heat content variance could not be directly related to wind fluctuations; this unexplained variance is probably related to shortwave radiative fluxes at the air-sea interface. 133 PM-043 McPHADEN, M.J., S.P. HAYES, L.J. MANGUM, and J.M. Toole. Variability in the western equatorial Pacific Ocean during the 1986-1987 El Nino/Southern Oscillation event. Air-Sea Interaction in Tropical Western Pacific, Proceedings, US-PRC International TOGA Symposium, Beijing, 1988, China Ocean Press, 41-58 (1990). No abstract. PM-044 McPHADEN, M.J., H.B. MILBURN, A.I. NAKAMURA, and A.J. SHEPHERD. PROTEUS: Profile Telemetry of Upper Ocean Currents. Sea Technology Magazine February 1991:10-19 (1991). No abstract. PM-045 McPHADEN, M.J., and J. Picaut. El Nifio-Southern Oscillation displacements of the western equatorial Pacific warm pool. Science 250:1385-1388 (1990). The western equatorial Pacific warm pool (sea-surface temperatures >29°C) was observed to migrate eastward across the date line during the 1986-1987 El Nino-Southern Oscillation event. Direct velocity measurements made in the upper ocean from 1986 to 1988 indicate that this migration was associated with a prolonged reversal in the South Equatorial Current forced by a large-scale relaxation of the trade winds. The data suggest that wind-forced zonal advection plays an important role in the thermodynamics of the western Pacific warm pool on interannual time scales. PM-046 MCPHADEN, M.J., A.J. SHEPHERD, W.G. Large, and P.P. Niiler. A TOGA array of drifting thermistor chains in the western equatorial Pacific Ocean: October 1989-January 1990. NOAA DR ERL PMEL-34 (PB91-224535), 171 pp. (1991). This report presents data collected from 19 drifting thermistor chains in the western equatorial Pacific Ocean between October 1989 and January 1990. The drifters were deployed as part of the TOGA program to study variability in the western equatorial Pacific warm pool. All drifters were equipped with 300 m long thermistor chains and 3 drifters were equipped with wind sensors. Data were telemetered in real- time to satellite via Service Argos. Drifter design, Argos data stream, data processing procedures, and overall system performance are described in detail. PM-047 Moritz, R.E., K. AAGAARD, D.J. Baker, L.A. Codispoti, S.L. Smith, W.O. Smith, R.C. Tipper, and J.E. Walsh. Arctic System Science: Ocean-atmosphere-ice interactions. Report of a Workshop held at the U.C.L.A. Lake Arrowhead Conference Center, March 12-16, 1990. ARCSS Workshop Steering Committee, Joint Oceanographic Institutions Incorporated, 132 pp. (1990). No abstract. PM-048 PAULSON, A.J. Cu interactions between dissolved and particulate organic matter in estuarine waters. Ph.D. Dissertation, University of Washington, Seattle, 252 pp. (1991). The partitioning of Cu by organic matter was investigated in estuarine waters. When whole primary sewage effluent was mixed with seawater, flocculation of dissolved Cu occurred initially, followed by remobilization of 25% of the total effluent Cu. A simple box model using the calculated remobilization rate of Cu (750 fig Cu m~2 day"1) correctly predicted an accumulation of 0.08 ,ug/l observed in the bottom waters of Puget Sound during a quiescent flow period. When 64Cu was added to whole seawater samples, the KD's of MCu were twice that of natural Cu. A limited number of hydrophobic organic sites that strongly complex Cu is postulated. The similarity in a KD for natural and added Cu based on the non-hydrophobic component of dissolved Cu indicates that Cu in solutions containing inorganic anions and possibly hydrophilic organic compounds is in equilibrium with estuarine particles. In a set of experiments with suspensions containing estuarine suspended matter, comparisons of the partitioning of natural Cu and MCu added in the ionic form were used to identify two components of natural Cu that did not completely equilibrate with dissolved ionic Cu: 1) Cu associated with dissolved hydrophobic organic matter; and 2) Cu contained in the residual component of the particulate phase. An understanding of the importance of dissolved organic matter in controlling the partitioning of Cu between the dissolved and particulate phases was obtained by comparing the partitioning of added Cu in a suspension made from filtered seawater with that made from filtered seawater in which the hydrophobic organic matter was removed. For the suspensions containing abiotic sediment trap particles, the removal of hydrophobic dissolved organic matter resulted in a two-fold increase in the particulate distribution coefficient (KD) of added MCu (from 10450 kg/1 to 104 81). The partitioning MCu in the suspensions 134 was controlled by chemical equilibria dominated by complexation with particulate and dissolved organic matter. In three similar sets of suspensions containing biotic particles, organisms indirectly controlled the partitioning of added Cu by excreting dissolved organic ligands and by coating particulate inorganic surfaces with organic matter. The behavior of natural Cu in these biotic suspensions indicate that biological processes are operating to retain particulate Cu against an opposing extra-cellular chemical driving force. PM-049 PAULSON, A.J., and H.C. CURL, JR. The biogeochemistry of trace metals in Hood Canal. Proceedings of Puget Sound Research '91, Seattle, WA, January 4-5, 1991, Puget Sound Water Quality Authority, 116-122 (1991). The Puget Sound Ambient Monitoring Program found elevated concentrations of iron, chromium, and vanadium at its Hood Canal site. Are these enrichments a result of rural development of the Hood Canal watershed or a result of natural processes occurring in this classic sub-oxic/anoxic fjord? This question is addressed using water column data from August 1986. In bottom waters the combination of organic matter decomposition and low oxygen can trap and redistribute redox-sensitive constituents and trace constituents that exist in marine particulate organic matter. Manganese is presented as an example. The low dissolved oxygen in bottom waters allows dissolved manganese diffusing from the sediments to remain in the water column. At the Great Bend where a strong horizontal oxygen gradient exists, dissolved manganese concentrations decreased dramatically. In this region, the precipitation of dissolved manganese results in particulate manganese concentrations as high as 40,000 ppm. Thus, manganese in the sediments near Lynch Cove enters the water column, precipitates near the Great Bend, and is trapped within the sediments of greater Hood Canal. This trapping and redistribution mechanism may also be affecting the distribution of other redox-sensitive metals such as iron, vanadium, and chromium. PM-050 PAULSON, A.J., H.C. CURL, JR., and E.D. COKELET. Remobilization of Cu from marine particulate organic matter and from sewage. Marine Chemistry 33:41-60 (1991). The possible causes of enrichments of dissolved Cu in the bottom waters of Puget Sound were examined in a series of experiments designed to measure the release of Cu from surface marine organic suspended matter and from sewage-derived particles under ambient conditions. Decomposition of organic matter and ion-exchange controlled the release of about one-third of the Cu bound to large particles (>53 fan). In contrast, no Cu was released from smaller particles (<53 fen) suspended in natural seawater and only 5% of the Cu on small particles was released into artificial seawater with a low dissolved Cu concentration. Within 15 min of mixing primary effluent with natural seawater, 40% of the dissolved Cu was lost from solution by flocculation. Between 15 min and 4 days, 25% of the total effluent Cu was released back into solution. This release could have originated either from particulate Cu on the original sewage particles or from the flocculated Cu that was formed from dissolved Cu within the first 15 min. The release of Cu into the bottom waters of Puget Sound from settling marine organic matter was calculated to have been between 1 and 8 fig Cu m"2 day"1, which is comparable with the diffusion of Cu from sediments. In contrast, the release of sewage-derived Cu could have been as high as 725 fig, Cu m"2 day-1 within 10 km of outfall. PM-051 PAULSON, A.J., H.C. CURL, JR., R.A. FEELY, T. GEISELMAN, K.A. Krogslund, G.J. MASSOTH, M.F. LAMB, and K. KELLY. Trace metal and ancillary data in the open waters of Puget Sound: 1980-1985. NOAA DR ERL PMEL-31 (PB91-201582), 56 pp. and 10 microfiche (1991). No abstract. PM-052 PAULSON, A.J., H.C. CURL, JR., R.A. FEELY, K.A. Krogslund, and S. Hanson. Trace metal and ancillary data in Puget Sound: August 1986. NOAA DR ERL PMEL-32 (PB91-201590), 35 pp. and 5 microfiche (1991). No abstract. PM-053 PAULSON, A.J., H.C. CURL, JR., R.A. FEELY, G.J. MASSOTH, K.A. Krogslund, T. GEISELMAN, M.F. LAMB, K KELLY, E.A. Crecelius, and J.F. GENDRON. Trace metal and ancillary data in the watersheds and urban embayments of Puget Sound. NOAA DR ERL PMEL-30 (PB91-201574), 72 pp. and 7 microfiche (1991). No abstract. 135 PM-054 REED, R.K. A year-long observation of water exchange between the North Pacific and the Bering Sea. Limnology and Oceanography 35(7):1604-1609 (1990). Knowledge of the exchange of waters between the North Pacific Ocean and Bering Sea is limited because of the lack of reliable measurements. Existing estimates of flow through the major pass (Amchitka) in the Aleutian Islands were disparate and based on short-term data. A 1-yr series of direct current measurements was obtained in this pass, which revealed a northward flow of warm Alaskan Stream water into the Bering Sea. An estimate of volume transport gave 2-3 x 106 m3 s"\ which is 10-15% of the transport of the Alaskan Stream. PM-055 REED, R.K. Circulation and water properties in the central Bering Sea during OCSEAP studies, Fall 1989-Fall 1990. NOAA TR ERL 446-PMEL 41 (NTIS not yet available), 13 pp. (1991) Data from three CTD surveys conducted during Outer Continental Shelf Environmental Assessment Program (OCSEAP) cruises in the central Bering Sea during fall 1989, spring 1990, and fall 1990 are used to examine circulation and property distributions. Geostrophic flow was quite variable, except in Pribilof and Zemchug Canyons where it was consistently westward. The variability of flow and small transports are difficult to reconcile with any permanent current system. The relatively cold temperatures near the temperature maximum suggest the absence of inflow through Amukta Pass near 172°W. The distributions of nutrients in fall 1989 and spring 1990 are also presented and discussed. PM-056 REED, R.K., and P.J. STABENO. Flow trajectories in the Bering Sea: Evidence for chaos. Geophysical Research Letters 17(12):2141-2144 (1990). A set of trajectories from drifting buoys in the Bering Sea is analyzed for evidence of chaos. The separation distance between drifters was found, in most cases, to have regions of exponential increase, which strongly suggests Lagrangian chaos. Analysis of the Kolmogorov entropy indicated a fractal dimension of 1.2 and a time scale of (22 d)"1. PM-057 ROACH, A.T., and J.D. SCHUMACHER. Observations of seasonal and interseasonal variability in Shelikof Strait, Alaska. Coastal Zone '91, Proceedings of 7th Symposium on Coastal and Ocean Management, ASCE/Long Beach, CA, July 8-12, 1991, 3304-3317 (1991). Nearly five years of monthly mean current data from two locations (one nearshore on the shallow shelf and one in the Shelikof sea valley) are used in conjunction with surface geostrophic winds and indices of freshwater discharge and sea-level atmospheric pressure to quantify the relative importance of these forcing terms on the ocean currents. The Alaska Coastal Current, a baroclinic jet formed upstream of Shelikof Strait, has a strong baroclinic signal with a maximum in the fall due to the seasonal freshwater cycle. This current is the primary influence on the nearshore currents. The Aleutian Low pressure system, an index of cyclones propagating into the Gulf of Alaska, dominates the meteorological field in the winter and causes a strengthening of currents in the sea valley. The currents in the sea valley are in approximate geostrophic balance. NEPPI FOCI, an index of the strength and persistence of the Aleutian Low, is a good index both of current fluctuations in the sea valley and of year-to-year variability of the mean currents. PM-058 SCHUMACHER, J.D., W.E. Barber, B. Holt, and A.K. Liu. Satellite observations of mesoscale features in Lower Cook Inlet and Shelikof Strait, Gulf of Alaska. NOAA-TR-ERL 445-PMEL 40 (PB92-101633), 18 pp. (1991). The Seasat satellite launched in summer 1978 carried a synthetic aperture radar (SAR). Although Seasat failed after 105 days in orbit, it provided observations that demonstrate the potential to examine and monitor upper oceanic processes. Seasat made five passes over lower Cook Inlet and Shelikof Strait, Alaska, during summer 1978. SAR images from the passes show oceanographic features, including a meander in a front, a pair of mesoscale eddies, and internal waves. These features are compared with contemporary and representative images from a satellite-borne Advanced Very High Resolution Radiometer (AVHRR) and Coastal Zone Color Scanner (CZCS), with water property data, and with current observations from moored instruments. The results indicate that SAR data can be used to monitor mesoscale oceanographic features. PM-059 Shuzhen, P., Y. Huiling, J. Toole, B. Millard, M.J. McPHADEN, and L.J. MANGUM. Comparison among autoregression models for forecasting El Nino events. Air-Sea Interaction in Tropical Western Pacific, Proceedings, US-PRC International TOGA Symposium, Beijing, 1988, China Ocean Press, 59-66 (1990). 136 SST (Sea Surface Temperature) data in a large area is used for spacial averages from which annual variation is subtracted to obtain a time series of SST anomalies of the cold tongue in the Tropical Eastern Pacific Ocean (Jan. 1951-Dec. 1985). An autoregression model, a self-exciting threshold autoregression model and an open loop autoregression model were developed, based on the time series. The interannual variations are simulated by those models. Results of simulations show that all the three models give good hindcasting of the nine El Nifio events since 1951. To test reliability of the open loop threshold model, forecasting was extended to the period Jan. 1986-Feb. 1987. It can be seen from the forecasting that the model can forecast the beginning stage and strengthening stage of the recent El Nino event (1986-1987). Correlation coefficients of estimations to observations are respectively 0.84, 0.88 and 0.89, for the three models. All the models obviously work well. The open loop threshold autoregression model is the best and most useful for monitoring the interannual variation of the cold tongue SST in the Eastern Tropical Pacific Ocean and for estimating El Nino strength. PM-060 Springer, S.R., M.J. MCPHADEN, and AJ. Busalacchi. Oceanic heat content variability in the tropical Pacific during the 1982-1983 El Nino. Journal of Geophysical Research 95(C12):22,089-22,101 (1990). Anomalous heat transport and storage during the 1982-1983 El Nino are investigated using a linear, multimode model forced by observed winds. Heat transport is decomposed into symmetric (about the equator) and antisymmetric components. The former was dominated by anomalous northward Ekman transport which represented an enhancement of the usual seasonal cycle. The latter involved both Ekman and geostrophic transports. Near-equatorial wind anomalies forced Kelvin and Rossby waves usually associated with El Nino; together these waves set up antisymmetric, geostrophic transport which tended to oppose direct Ekman transport. Because the opposition was imperfect, there was net heat convergence which caused variations in heat content in bands of latitude centered on the equator. Within a fairly narrow band (±5°) heat content was anomalously high preceding El Nifio and was depleted following the event. Equatorial heat content anomalies were largely compensated by opposing anomalies in low latitudes of the extraequatorial ocean so that variability over broader bands of latitude about the equator was relatively small. A sampling study employing the model suggests that observational evidence for a heat content variations over the region ±15° is an artifact arising from inadequate spatial resolution offered by the sea level measurement network. PM-061 STABENO, PJ., and R.K. REED. Recent Lagrangian measurements along the Alaskan Stream. Deep-Sea Research 38:289-296 (1991). During 1986-87, 26 satellite-tracked drifting buoys were deployed on the shelf in the northern Gulf of Alaska; nine of these buoys entered the Alaskan Stream. The buoy trajectories showed a well-formed, narrow, high-speed current. Southern deviations from the high- speed core were generally wind-induced. All but one of the drifters eventually went aground on one of the Aleutian Islands or entered the Bering Sea. Some meandering of the path of the Alaskan Stream was evident just west of Kodiak Island but was not apparent farther downstream. PM-062 TAFT, B.A., and M.J. McPHADEN. Diurnal cycle of sea-surface temperature in the western tropical Pacific. Air-Sea Interaction jn Tropical Western Pacific, Proceedings, US-PRC International TOGA Symposium, Beijing, 1988, China Ocean Press, 343-352 (1990). No abstract. PM-063 Todd, J.F., D.K. ATWOOD, R.A. FEELY, and J.G. TOGGWEILER. Atmosphere-ocean exchange of carbon dioxide: Implications for climate and global change on seasonal-to-century time-scales. NOAA Climate and Global Change Program Special Report No. 3, Boulder, CO, 31 pp. (1990). No abstract. PM-064 Toole, J., T. Delcroix, G. Eldin, E. Firing, M. Francis, C. Henin, S. Jiang, L. MANGUM, R. Millard, J. Picaut, S. Pu, M. Radenac, Z. Wang, E. Zou. Evolution of the western Pacific Ocean during the 1986-1987 El Nino. Air-Sea Interaction in Tropical Western Pacific, Proceedings, US-PRC International TOGA Symposium, Beijing, 1988, China Ocean Press, 79-90 (1990). A series of 12 meridional transects along longitude 165°E in the western equatorial Pacific Ocean were made between mid-1986 and mid-1988: a time interval spanning an El Nino/Southem Oscillation (ENSO) event. Data collected on these cruises provide a detailed (albeit temporally sparse) view of the oceanic changes which occur in the western Pacific during an ENSO event. The present work focuses on the evolution of the upper ocean thermohaline and zonal velocity fields as revealed by high resolution hydrographic casts and direct near surface 137 velocity measurements. Onset of the El Nino was characterized by anomalous eastward transport of warm surface waters equatorward of 10° latitude (where anomalies are relative to a mean state defined by historical hydrographic data and recent observations during non-ENSO periods). The thermocline in the western Pacific shoaled in response to this export of surface water; near-equator surface dynamic height relative to 105 hPa at event peak was 20 dyn cm below historical non-El Nino levels. Vertical displacements of the water column which resulted in the dynamic height changes were confined to the upper 300-400 m of the ocean. Later in time, strong westward transport anomalies were observed and by mid-1988, sea level had recovered to its historical mean level. PM-065 Wolfe, G.V., T.S. BATES, and R.J. Charlson. Climatic and environmental implications of biogas exchange at the sea surface: Modeling DMS and the marine biologic sulfur cycle. In Ocean Margin Processes jn Global Change. R.F.C. Mantoura, J.-M. Martin and R. Wollast (eds.). Wiley, New York, 383-400 (1991). The direct and indirect climatic effects of trace gas emission by oceanic biota are considered; it is shown that the highest potential sensitivities derive from the change in remote marine stratus cloud albedo due to dimethyl sulfide (DMS) emissions. As a paradigm for modeling trace biogas emissions, a hierarchy of box models is employed to explore the controlling variables on the biogenic production of this gas in the global ocean. This remote marine scenario is contrasted with the climatic and environmental impacts of coastal regions, and the coupling of the sulfur cycle with those of other trace gases is considered. The need to understand controlling variables and processes is stressed as a means to understand the stability of the system. PM-066 Young, R.W., K.L. Carder, P.R. Betzer, D.K. Costello, R.A. Duce, G.R. DiTullio, N.W. Tindale, E.A. Laws, M. Uematsu, J.T. Merrill, and R.A. FEELY. Atmospheric iron inputs and primary productivity: Phytoplankton responses in the north Pacific. Global Biogeochemical Cycles 5(2): 119-134 (1991). As part of the Asian Dust Inputs to the Ocean System (ADIOS) project, atmospheric dust fluxes and primary productivity were monitored during the dusty season (spring) of 1986 at 26°N, 155°W, in the North Pacific Ocean. The arrival of major pulses of dust from Asia was followed by major increases in primary production. Extensive chemical analyses of the atmospheric particles showed that they were iron-rich (10-15%) and, further, that if only a small proportion (e.g., 10%) of this iron dissolved in the euphotic zone, it would be sufficient to support the increases in carbon production at this location. The systematic increases in production noted with increasing depth and time may result from a continual release of iron from the settling particles in the euphotic zone. At all depths, systematic decreases in production followed the initial surge in production, indicating that the phytoplankton may have evolved from being iron-limited to being nitrogen-limited. Comparison of particle concentrations calculated by a particle settling model with primary productivity profiles indicated that mineral particles with settling velocities equivalent to those of 14 to 18-/an-diameter spherical quartz particles were the most likely source for the iron stimulating the increases in primary production. PM-067 Zongshan, W„ Z. Emei, J.M. Toole, L.J. MANGUM, X. Bochang, and Y. Keqi. Oceanic event during the 1986-1987 El Nino. Air-Sea Interaction in Tropical Western Pacific, Proceedings, US-PRC International TOGA Symposium, Beijing, 1988, China Ocean Press, 15-26 (1990). In this paper, the oceanic event of the generation, development and decay of the 1986-1987 El Nino, is analyzed according to the data obtained in four cruises of the Sino-US joint air-sea interaction studies in the Western Tropical Pacific Ocean, together with the data of wind and SST provided by NOAA and that of sea level presented by Dr. Wyrtki of the University of Hawaii. It is pointed out that the 1986-1987 El Nino is a little bit stronger than the medium. The macroscropic variations of SSTs and sea levels are synchronous and similar. Meanwhile, they relate to the features of wind fields. The variations of subsurface temperature structures corresponded to the eastward transport of the warm water in the upper layer and the structures and directions of the current system changed extraordinarily in the western tropical Pacific during this El Nino. In the precursor of the event, SEC was strong and the warm water piled up in the western Pacific. In the onset phase, a wide-range (12.5° lat) eastward current was formed, resulting in the eastward transport of the warm water. In the decline phase, NECC became weak and SECC became strong. After the El Niflo ended the ocean was in dynamical adjustment and the westward currents occupied a wide-range area (about 12° lat) near the equator. During this El Nino, total eastward volume transport in the western tropical Pacific is 11.4 x 10u m3, which is 1/3 greater than that of the 1976 El Nino and about 2/5 less than that of the 1982/1983 El Nino. 138 Addendum PM-068 Arlander, D.W., D.R. Cronn, J.C. Fanner, F.A. Menzia, and H.H. Westburg. Gaseous oxygenated hydrocarbons in the remote marine troposphere. Journal of Geophysical Research 95(D10):16.391-16,403 (1990). Measurement of the background levels and study of the chemistry of trace organic carbon species in the remote marine troposphere occurred during an April-July 1987 SAGA II cruise in remote regions of the Pacific and Indian Oceans. Measured compounds included carboxylic acids, formaldehyde, light hydrocarbons (C2-C4), and ozone. The results show seasonal, dieL, and spatial dependencies for the organic acids. Distinct latitudinal gradients are seen for most sampled compounds. Formic acid is well correlated with suspected precursors, formaldehyde and light hydrocarbons. Acetic acid follows a similar pattern as formic acid, although its precursors are as yet undefined. Diel patterns of low amplitude for the organic acids in the remote marine troposphere suggest a natural contribution to tropospheric photochemistry, and to the global carbon cycle as well. For the northern hemisphere Pacific Ocean, the mean formic acid mixing ratio was 0.80 ± 0.30 ppbv, the mean acetic acid value was 0.78 ± 0.32 ppbv. For the southern hemisphere Pacific Ocean, formic acid averaged 0.22 1 0.13 ppbv, for acetic acid, the mean was 0.28 ± 0.18 ppbv. For the northern hemisphere Indian Ocean, the mean formic acid mixing ratio was 0.75 ± 0.24 ppbv, and the mean acetic acid value was 0.69 ± 0.27 ppbv. For the southern hemisphere Indian Ocean, the mean formic acid value was 0.19 ± 0.17 ppbv, and the mean acetic acid value was 0.29 ± 0.16 ppbv. Highest levels of organic acids were encountered near known anthropogenic source regions, in air masses of continental origin, or near regions of naturally produced alkenes (C2, C3). The ozone-alkene oxidation scheme appears to play a major role in gas phase organic acid production in the remote marine troposphere. Nighttime gas phase deposition of the organic acids onto the ocean surface appears to be a major sink. PM-069 BATES, T.S., AD. Clarke, V.N. Kapustin, J.E. JOHNSON, and R.J. Charlson. Oceanic dimethylsulfide and marine aerosol: Difficulties associated with assessing their covariance. Global Biogeochemical Cycles 3(4):299-304 (1989). Simultaneous measurements of oceanic dimethylsulfide (DMS), atmospheric aerosol sulfate and the size-resolved physical properties of the aerosol were made aboard a ship in the equatorial Pacific during July 1987. Under light and variable winds, in an area essentially free of continental and anthropogenic air masses, an observed increase in oceanic DMS concentrations preceded simultaneous increases in non-sea salt sulfate aerosol, the fraction of volatile submicrometer (sub-/an) aerosol, the condensation nuclei population, and the mean particle diameter of the sub-/an aerosol. Although the increase in oceanic DMS can qualitatively account for the corresponding changes in the atmospheric aerosol particles, there are numerous difficulties in quantifying the relationship between the sea-to-air flux of DMS and the formation and growth of atmospheric aerosol particles. PM-070 Martin, D.C., D. BORG-BREEN, J.C. Martin, and A.P. Streissguth. Microcomputer measurement and analysis of newborn sucking. Behavior Research Methods, Instruments, & Computers 22(4):393-401 (1990). An on-line Basic computer program with on-line monitor prompts and read-out collects, stores, and digitizes pressure and latency of sucking responses for later analyses. The program and analog equipment are described, and approximate costs are noted. 139 SPACE ENVIRONMENT LABORATORY SE-001 Baker, D.N., D.H. Fairfield, J. A. Slavin, I.G. Richardson, J.D. Craven, LA. Frank, R.C. Elphic, H.J. Singer, C.J. Owen, and R.D. ZWICKL, The substorm event of 28 January 1983: A detailed global study. Planetary & Space Science. 18(12): 1495-1515 (1990). A small, isolated substorm with an expansion phase onset at 07:39 U.T. (±1 min) on 28 January 1983 was well observed by ground-based instrumentation as well as by low- and high-altitude spacecraft. This event period was chosen as a detailed analysis inter- val because of the comprehensive nature of the data coverage, and because ISEE-3 identified signatures within the distant tail -220 Re) following the substorm onset which had been interpreted as those of a plasmoid passage. In this paper we provide a comprehensive timeline of the growth, expansion, and recovery phases of the substorm. The magnetospheric energy input rates are evaluated using IMP-8 in the upstream solar wind. For the first time, DE-1 imaging sequences are used to examine auroral features during the growth and expansion phases while ISEE-3 was in the deep tail. Substorm current wedge location and expansion onset information was pro- vided by ground-based magnetometer and geostationary orbit (particle and magnetic field) data. The plasma, energetic particle, and field signatures at ISEE-3 are considered within the framework of the near-Earth data sets. We quantitatively estimate substorm ener- gy input and output relationships for this case and we evaluate the timing and physical dimensions of the distant tail disturbance im- plied by the global observations available. Overall, the present analysis provides a thorough documentation of a substorm to an unprec- edented degree: most of the data support the developing paradigm of the near-Earth neutral line and plasmoid formation model. We also consider the boundary layer dynamics model of substorms as an alternative explanation of the global magnetospheric phenomena in this event, but as presented this model does not provide a superior organization of the available data sets. SE-002 BALCH, C.C., A probability forecast for geomagnetic activity. In Solar-Terrestrial Predictions: Proceedings of a Workshop al Leura. Australia. October 16-20. 1989. Volume 2, R.J. Thompson, D.G. Cole, P.J.Wilkinson, M.A. Shea, D. Smart, and G. Heckman (eds.). U.S. Department of Commerce, Boulder, Colorado, 13-17 (1990). A proposal for adopting probability forecasts is discussed. The current method of a single value A-index forecast has numerous disadvantages. A new, simplifying approach is to adopt a probability forecast for occurrence of six discrete levels of geomagnetic activ- ity. The probability forecast allows forecasters to communicate to the users the level of confidence in the occurrence of significant levels of activity. This is a more realistic representation of our forecast capability and is of greater value to the user of the forecast in making operational decisions. A discussion of the implications of such a program on the forecast analysis process, the necessary sup- porting forecasting tools, forecast verification, and customer applications are discussed. SE-003 BALCH, C.C., Space environment support to spacecraft operations at SESC: Past, present, and future. In Solar-Terrestrial Predictions: Proceedings of a Workshop al Leura. Australia. October 16-20. 1989. Volume 2, R.J. Thompson, D.G. Cole, P.J.Wilkinson, M.A. Shea, D. Smart, and G. Heckman (eds.). U.S. Department of Commerce, Boulder, Colorado, 18-24 (1990). The mission of the Space Environment Services Center, Boulder, is to provide support and services to users who are affected by the space environment. A significant group of such users is the spacecraft industry. In addition to providing routine types of support to spacecraft operations, such as alerts, warnings, and various products, SESC has implemented a spacecraft anomaly analysis service. This paper discusses the evolution of the service, some characteristics of the anomalies that have been reported, and problems encoun- tered. Plans for the future are also discussed. SE-004 Barrow, C.H., J. Watermann, D.S. EVANS, and K. Wilhelm, Observations of Antarctic auroral electron precipitation with high stability in time and longitude. Annales Geophysicae. 9: 259-266 (1991). Electron flux measurements were made in the energy range 0.1 to 12.5 keV, by the electron spectrometer 1ES019 on board Space- lab 1, during the period 29 November to 7 December 1983. The spacecraft was in a 57-degree inclnation circular orbit at an altitude of about 250 km with an orbital period of 90 min. Although the experiment was originally designed for artificial electron beam re- sponse observations, several periods of natural energetic electron precipitation were also recorded and these have been surveyed and catalogued. The data are interesting because of the high resolution of the electron spectrometer, the relatively low spacecraft altitude for the observations and the path of Spacelab 1 almost along the auroral oval. On 30 November 1983 Spacelab 1 observed electron precipitation during four successive southern hemisphere passes, one of which is of particular interest as the NOAA-7 satellite, which measured electron flux in the energy range 0.3 to 20 keV at an altitude of about 850 km, was then quite close in space and time. As correlative riometer and magnetometer observations suggest that auroral conditions remained stable during the 25-min period be- tween the two sets of observations, the observations are used to infer the gross spatial structure of the auroral precipitation over the midnight sector. Comparison of the electron energy spectra observed by Spacelab 1 and NOAA-7 at different magnetic local times and at different altitudes suggests a high degree of longitudinal homogeneity in the precipitation. 140 SE-005 Bastian, TS. and A.L Kiplinger, VLA and H-alpha observations of the M8.7 flare of 17 June 1989: A preliminary report. In Max '91/SMM Solar Flares: Observations and Theory. Proceedings of Max '91 Workshop No. 3, Estes Park, Colorado, June 3-7, 1990, R.M. Winglee and A.L. Kiplinger (eds.). University of Colorado, Boulder, 153-161 (1991). The Very Large Array (VLA) was used on 17 June 1989 during the first Max '91 observing campaign to obtain dual frequency imaging of a large, extended flare with a time resolution of 1.66 s. We present a preliminary description of the 5 GHz data and com- pare them with observations made with the High Speed H-alpha Camera and with the KPNO photospheric magnetogram. SE-006 BORNMANN, PL, Comparisons between CA XIX line profiles derived from simple fluid models and observations made by SMM's bent crystal spectrometer. In Max '91/SMM Solar Flares: Observations and Theory. Proceedings of Max '91 Workshop No. 3, Estes Park, Colorado, June 3-7, 1990, R.M. Winglee and A.L Kiplinger (eds), University of Colorado, Boulder, 88-94 (1991). During the rise of the soft x-ray flare emission, the resonance line of Ca XIX exhibits strong, blue-shifted wing emission and excess line broadening. Although these line profiles can be successfully reproduced using multiple blue-shifted gaussians, alternate fluid flows are considered in this paper. The simple fluid models representing the flow of material in a jet and through a pipe are considered. In both models, the velocity at each location in the flow is calculated from analytic expressions, which are then converted to produce theoretical line profiles. These theoretical profiles are then compared with Ca XIX line profiles observed by SMM's Bent Crystal Spec- trometer. Reasonable agreement is found with the jet model, while the pipe model is unable to reproduce the observed line profiles. The optimal fluid parameters for the jet model were within the ranges expected for solar flare conditions. SE-007 BORNMANN, PL, Solar x-ray physics. In U.S. National Report 1q International Union of Geodesy and Geophysics 1987-1990. Reviews of Geophysics, Supplement, 915-924 (1991). This is a review of the research in solar x-ray phenomena that has been done by American scientists in the last four years. This research ranges from new instrumentation, such as multilayer mirrors and high spectral resolution detectors, to refined theories and observations of the flare process. Contributions have been made in our understanding of x-ray bright points, solar active regions, solar flares, and flare-associated phenomena. The hard x-ray spectra during the impulsive phase of solar flares have been examined in great- er detail and found, among other things, to fit a double power law. Models for the hard x-ray emissions have focused largely on elec- tron acceleration by field-aligned currents, although other models such as proton beams, waves, and neutral beams have also been investigated. Correlations between the hard x-ray emission and radio, ultraviolet, and gamma-ray emissions have been used to provide additional constraints on the flare models. The process known as chromospheric evaporation, which is seen as blueshifts of the soft x-ray line profiles, has been explored through further analysis of the observations and the development of new models. New atomic calculations have been performed so that further information about the plasma properties during observations have been used to iden- tify new x-ray features such as flaring arches and giant post-flare arches. Other topics of investigation included the energy in solar flares and the long-term variations in solar indices, the 155-day periodicity in solar flares, and the distribution of flares on the solar disk. Finally, associations have been made between the solar x-ray emission and the phenomena of coronal mass ejections and solar energetic particles, as well as the effect of this radiation on the earth's upper atmosphere. SE-008 BORNMANN, PL, D. Kalmbach, D. Kulhanek, and A. Casale, A study of the evolution of solar active regions for improving solar flare forecasts. In Solar-Terrestrial Predictions: Proceedings oi a Workshop al Leura. Australia. October 16-20. 1989. Volume 1, R.J. Thompson, D.G. Cole, P.J.Wilkinson, M.A. Shea, D. Smart, and G. Heckman (eds.). U.S. Department of Commerce, Boulder, Colorado, 301-308 (1990). Statistics on the frequency of transition between active region classes were calculated and used to derive the expected rate of flar- ing for the next 2-7 days. Five years of Mcintosh active region classifications were analyzed using the newly developed software called TELSAR (Tracking and EvoLution of Solar Active Regions). The most frequent transitions between these 63 different classes usually involve a single-step change in one of the three classification parameters. The evolution of the classes and the average, single-day flare rate were used to predict flare rates for each class over the next several days. For flares of X-ray class M (peak 1-8 A flux between 10~5 and 10"4 Wm~2), these rates can differ from persistence predictions by more than 0.5 flares per day, although a more typical dif- ference is 0.1 flares per day. The rarity of some classes suggests that merging these classes with others may improve flare statistics and thereby improve flare forecasts. SE-009 Burkhart, G.R., and J. Chen, Differential memory in the Earth's magnetotail. Journal oi Geophysical Research. 96(A8): 14,033-14,049 (1991). The process of differential memory is quantitatively studied in the modified Harris magnetotail geometry. This process arises as a consequence of nonlinear particle dynamics in the magnetotail, which gives rise to partitioning of phase space into disjoint regions. 141 Different regions are occupied by distinct classes of orbits and have widely separated time scales. This paper gives the first study of the time scales and potentially observable signatures in plasma distribution functions associated with the process of differential memory. It is found that the effective "trapping" time of stochastic orbits plays a critical role in differential memory, and that in the magnetotail geometry this time has resonances at certain values of the parameter H. A scaling law Hx/A has been found for this previously un- known resonance effect. This scaling is directly related to the phase space structures of this stochastic system and leads to signatures in the distribution functions; their velocity moments (Density, velocity components, and kinetic temperatures) are computed following a prescribed change in the boundary conditions. The relationships between the initial changes and the time-asymptotic distribution func- tions are discussed. The results depend only on the large-scale phase space structures and not on individual chaotic orbits. SE-010 Burkhart, G.R., J.F. Drake, and J. Chen, Structure of the dissipation region during magnetic reconnection in collisionless plasma. Journal of Geophysical Research. 96(A7): 11,539-11,553 (1991). The results of an analytic and numerical investigation of the structure of the X line during steady state magnetic reconnection in collisionless plasma are presented. The structure of the X line essentially depends on a single dimensionless parameter F, which is a measure of the influx of plasma into the reconnection region. For small F the self-consistent plasma current driven at the X line is small, and the magnetic fields are nearly unchanged from the initial vacuum state. With increasing F the current driven at the X line becomes large, and the dissipation region collapses in the direction of the inflow and elongates along the outflow. For sufficiently large F the velocity of the plasma ejected from the X line exceeds the local Alfven velocity. In this regime a fast mode shock forms at the outflow end of the dissipation region, which slows the high-velocity outflow plasma to the subsonic flow characteristic of the broader outflow region. Finally, at a critical plasma flux Fc the dissipation region collapses to zero thickness; no steady solutions are found for F > Fc. By matching the energy dissipated at the neutral line with the change in global magnetic energy, a self-consistent equation for F is derived which indicates that F always adjusts so that F > Fc. Predictions of reconnection rates and associated parameters for the geomagnetic tail are presented which are in reasonable agreement with observations. SE-011 Burkhart, G.R., R.F. Martin, Jr., P.B. Dusenbery, and T.W. SPEISER, Neutral line chaos and phase space structure, Geophysical Research Letters. 18: 1591-1594 (1991). Numerical surface of section techniques and analytic methods are used to study phase space structure and chaos near a neutral line. We find that, for - (2h)1^2 <, Py <, {2h)x^2 , the ratio of fields, b„, rather than k, is the appropriate chaos parameter, where Py and h are the normalized canonical momentum and energy. We find that the action integral adiabatic constant is approximately conserved and can be used to describe particle motion as long as£„ < < 1 orbn > > 1. SE-012 Burnside, R.G., C.A. Tepley, M.P Sulzer, TJ. Fuller-Rowell, D.G. Torr, and R.G. Roble, The neutral thermosphere at Arecibo during geomagnetic storms. Journal of Geophysical Research. 96(A2): 1289-1301 (1991). Over the past five years, simultaneous incoherent scatter and optical observations have been obtained at Arecibo, Puerto Rico, during two major geomagnetic storms. The first storm we examine occurred during the World Day campaign of 12-16 January 1988, where on 14 January 1988, Kp values greater than 7 were recorded. An ion-energy balance calculation shows that atomic oxygen den- sities at a fixed height on 14 January 1988 were about twice as large as they were on the quiet days in this period. Simultaneous radar and Fabry-Perot interferometer observations were used to infer nighttime O densities on 14-15 January 1988 that were about twice as large as on adjacent quiet nights. On this night, unusually high westward ion velocities were observed at Arecibo. The Fabry-Perot measurements show that the normal eastward flow of the neutral wind was reversed on this night. The second storm we examine oc- curred on the night of 13-14 July 1985, when Kp values reached only 4+ , but the ionosphere and thermosphere responded in a simi- lar manner as they did in January 1988. On the nights of both 13-34 July 1985 and 14-15 January 1988, the electron densities ob- served at Arecibo were significantly higher than they were on nearby geomagnetically quiet nights. These results indicate that major storm effects in thermospheric winds and composition propagate to low latitudes and have a pronounced effect on the ionospheric structure over Arecibo. SE-013 Canfield, R.C., A.L. Kiplinger, M.J. Penn, and J.-P Wulser, Ha spectra of dynamic chromospheric processes in five well-ordered x-ray flares. TJie Astrophysical Journal. 363: 318-325 (1990). We have obtained simultaneous Ha and hard x-ray (HXR) spectra of five solar flares. We find spectroscopic signatures of three observationally distinct types of chromospheric mass motions before, during, or after the HXR impulsive phase. In this paper we char- acterize Ha spectra in relation to the impulsive phase and discuss physical mechanisms that might explain these relationships. The most common dynamic phenomenon, which appears in many regions of all five flares, shows impulsive-phase redshifted Ha in emis- sion. This impulsive-phase redshifted emission is temporally and spatially associated with intense HXR emission and broad impulsive- 142 phase Ha wings. Some flares show multiple impulsive HXR burst periods and multiple Ha redshift episodes. In agreement with other recent work, we associate these phenomena with downward-moving chromospheric condensations driven by chromospheric evap- oration. A few small regions within two of the five flares show blueshifted Ha emission spectra which appear only early in the impul- sive phase, but not before. These spectra are temporally correlated with hard x-ray emission but not with broad Ha wings (no hard x-ray images are available for these two events). The blueshifts have lifetimes between 1 and 2 minutes. They could be a consequence of heating of the deep chromosphere by precipitating nonthermal electrons with energy > 10 keV, but more likely are the manifesta- tion of impulsive-phase heating of chromospheric material which was accelerated upward by some hydromagnetic process. Finally, there are both redshifted and blueshifted absorption spectra with properties fully consistent with what is known about erupting and untwisting filaments. SE-014 Chen, J., G.R. Burkhart, and C.Y. Huang, Observational signatures of nonlinear magnetotail particle dynamics. Geophysical Research Letters. 17(12): 2237-2240(1990). It has been predicted that the nonlinear particle dynamics in the magnetotail leads to a class of resonance structures in the quiet- time ion distribution functions in the Central Plasma Sheet. These structures exhibit a scaling law of f/1//4. In this letter, we report the first identification of such a scaling law in quiet-time CPS distribution functions obtained aboard ISEE 1. We propose a method which uses the observed resonance structures to determine the quiet-time current sheet thickness based on a measurement of the distribution function and magnetic field obtained by one satellite. SE-015 Coroniti, F.V., E.W. Greenstadt, B.T. Tsurutani, E.J. Smith, R.D. ZWICKL, and J.T Gosling, Plasma waves in the geomagnetic tail: ISEE 3. Journal of Geophysical Research. 95(A12): 20,977-20,995 (1990). The plasma wave measurements, obtained during ISEE 3's deep passes through the geomagnetic tail found that moderate to in- tense electric field turbulence occurred in association with the major plasma and magnetic field regions and flow phenomena. In the magnetopause boundary layer the electric field spectral amplitudes are typically sharply peaked at 316 Hz to 562 Hz. The tail lobe region which is upstream of slow shocks and is magnetically connected to the plasma sheet is characterized by wave spectra that peak in the 100- to 316-Hz range and at the electron plasma frequency. Within the plasma sheet, broadband electrostatic noise occurs in regions where the magnetic field strength exceeds 2 nT; this noise can also be found in the plasma sheet boundary layer in association with strong field-aligned plasma flows. As ISEE 3 moved between the different distant tail regions, distinct but often subtle changes occurred in the plasma wave spectra. Occasionally, plasma oscillations indicate that the distant tail contains a population of relatively dense cold electrons. SE-016 DAVIES, K., and X.M. Liu, Ionospheric slab thickness in middle and low latitudes. Radio Science. 26(4): 997-1005 (1991). The equivalent slab thickness of the ionosphere at 15 stations in middle and low latitudes was studied to determine its dependence on solar cycle and location. The data were grouped by season. The following are the major conclusions. There appears to be little or no geographical, or geomagnetic, dependence. The slab thickness varies approximately linearly with the 12-month smoothed values of the 10.7-cm solar radio flux. In middle latitudes the winter midnight thickness is essentially independent of the flux, whereas in sum- mer and equinox the midnight thickness increases with increase of solar flux. The noon thickness increases with increase of solar flux in all seasons. The zero-order Fourier coefficients for the diurnal curves at all 15 stations were expressed as linear functions of the 10.7-cm flux. The higher harmonic coefficients showed no appreciable dependence on solar flux. The pronounced predawn increase in slab thickness is caused by low values of the maximum electron density, not by increase of total electron content. SE-017 DETMAN, TR., M. DRYER, T Yeh, S.M. Han, S.T Wu, and D.J. McComas. A time-dependent, three-dimensional MHD nu- merical study of interplanetary magnetic draping around plasmoids in the solar wind. Journal of Geophysical Research. 96(A6): 9531-9540(1991). A spherical plasmoid is injected into a representative solar wind at 18 solar radii, which is chosen as the lower computational boundary of a 3-dimensional MHD model. The field line topology of the injected plasmoid resembles the streamline topology of a spherical vortex. Evolution of the plasmoid and its surrounding interplanetary medium is described out to approximately 1 AU for three cases with different velocities imparted to the plasmoid. In the first case a plasmoid enters the lower boundary with a velocity of 250 km s"1 equal to the steady state background solar wind velocity at the lower boundary. In the second and third cases the plasmoid enters with peak velocities of twice and three times the background velocity. A number of interesting features are found. For in- stance, the evolving plasmoid retains its basic magnetic topology although the shape becomes distorted. As might be expected, the shape distortion increases with the injection velocity. Development of a bow shock occurs when the plasmoid is injected with a velocity greater than the sum of the local fast magnetosonic speed and the ambient solar wind velocity. The MHD simulation demonstrates magnetic draping around the plasmoid. 143 SE-018 DONNELLY, R.F., Temporal variations of solar UV, EUV, and x-ray fluxes, sunspot number, and F10. In Solar-Terrestrial Predictions: Proceedings of a Workshop ai Leura. Australia. October 16-20. 1989. Volume 1, R.J. Thompson, D.G. Cole, P.J. Wilkinson, M.A. Shea, D. Smart, and G. Heckman (eds.). U.S. Department of Commerce, Boulder, Colorado, 381-385 (1990). Predictions of future values of sunspot number (R) and Ottawa solar 10.7 cm flux (F10) are made as surrogate estimators of the solar radiative fluxes that heat, photodissociate, and ionize the terrestrial atmosphere because only R and F10 have long enough time series to apply time series analyses for developing predictions. Data sets of solar UV, EUV, and x-ray fluxes have been too short in duration to be used to develop predictions of solar cycle variations. Systematic differences in the temporal variations of solar UV, EUV, and x-ray measurements relative to the classical solar indices are discussed for the shape of the solar cycle, intermediate-term variations (4-11 months), and short-term variations (Days, weeks). SE-019 DONNELLY, R.F., and LC. PUGA, Thirteen-day periodicity and the center-to-limb dependence of UV, EUV, and x-ray emission of solar activity. Solar Physics. 130: 369-390 (1990). Periodicity in the 13-14 day range for full-disk UV fluxes comes mainly from episodes of solar activity with two peaks per rotation, produced by the solar rotational modulation from two groups of active regions roughly 180° apart in solar longitude. Thirteen-day periodicity is quite strong relative to the 27-day periodicity for the solar UV flux at most wavelengths in the 1750-2900 A range, be- cause the rapid decrease in UV plage emission on average with increasing solar central angle shapes the UV variations for two peaks per rotation into nearly a 13-day sinusoid, with deep minima when the main groups of active regions are near the limb. Chromospheric EUV lines and ground-based indices have moderate 13-day periodicity, where the slightly greater emission of regions near the limbs causes a lower strength relative to the 27-day variations than in the above UV case. The lack of 13-day periodicity in the solar 10.7 cm flux is caused by its broad central angle dependence that averages out the 13-day variations and produces nearly sinusoidal 27-day variations. Optically thin full-disk soft x-rays can have 1 3-day periodicity out of phase with that of the UV flux because the x-ray emis- sion peaks with both groups of active regions are within view, one group at each limb, when the optically thick UV flux is at a rotation- al minimum. The lack of 13-day periodicity in the UV and soft x-ray fluxes shows that the active region emission in these strong lines is not optically thin; resonant scattering is suggested to cause an effective optical depth near unity in these hot coronal lines for active regions near the limb. SE-020 DRYER, M., Z.K. SMITH, A.J. Coates, and A.D. Johnstone, The February 1986 solar activity: A comparison of GIOTTO, VEGA-1, and IMP-8 solar wind measurements with MHD simulations. Solar Physics. 132: 353-371 (1991). Large disturbances in the interplanetary medium were observed by several spacecraft during a period of enhanced solar activity in February 1986. The locations of six solar flares and the spacecraft considered here encompassed more than 100° of heliolongitude. These flares during the minimum of cycle 21 set the stage for an extensive multi-spacecraft comparison performed with a two- dimensional, magnetohydrodynamic (MHD) numerical experiment. The plasma instruments on the European Space Agency (ESA)'s GIOTTO spacecraft, on its way to encounter Comet Halley in March 1986, made measurements of the solar wind for up to 8 hours per day during February. We compare solar wind measurements from the Johnstone Plasma Analyzer (JPS) experiment on GIOTTO with the MHD simulation of the interplanetary medium throughout these events. Using plasma data obtained by the IMP-8 satellite in addition, it appears that an extended period of high solar wind speed is required as well as the simulated flares to represent the inter- planetary medium in this case. We also compare the plasma and magnetometer data from VEGA-1 with the MHD simulation. This comparison tends to support an interpretation that the major solar wind changes at both GIOTTO and VEGA-1 on 8 February 1986 were due to a shock from a W 05° solar flare on 8 February 1986 (06:25 UT). The numerical experiment is considered, qualitatively, to resemble the observations at the former spacecraft, but it has less success at the latter one. SE-021 DRYER, M., S.T Wu, and T.R. DETMAN, Numerical simulations of solar disturbances and their interplanetary consequences, In Basic Plasma Processes on Ihe. S_Mn. Proceedings of IAU Conference 142, E.R.. Priest and V Krishan (eds.), 331-340 (1990). Responses of the solar atmosphere and interplanetary medium to simulated solar disturbances were studied by time-dependent, MHD numerical simulations. This deterministic initial-boundary value problem was attacked in the classical way: a representative steady state is first established, then input parameters at the lower near-Sun boundary are perturbed. We discuss a number of 2- and 3-dimensional examples of coronal mass ejection (CME) simulations and some current controversies concerning the basic process of CME initiation. Footpoint shearing motion is tested to see whether it can provide a reasonable mechanism for CME development from arch filament configurations. We also demonstrate possible interplanetary consequences to CME-like disturbances by using 3-D simula- tions to determine the dynamic response of the solar wind to a plasmoid injection from an eruptive filament or prominence. We also discuss the separate possibility whereby a plasmoid may be generated in the interplanetary medium by a solar-generated shock that propagates through a heliospheric current sheet. Application of the 3-D model for the interpretation of interplanetary scintillation observations is also discussed. 144 SE-022 DUNBAR, P.K., and J.W. HIRMAN, Boulder IUWDS activity for 1984-1989, In Solar-Terrestrial Predictions: Proceedings oi a Workshop at Leura. Australia. October 16-20. 1989. Volume 1, R.J. Thompson, D.G. Cole, P.J. Wilkinson, M.A. Shea, D. Smart, and G. Heckman (eds.). U.S. Department of Commerce, Boulder, Colorado, 391-399 (1990). The Space Environment Services Center (SESC) in Boulder, Colorado, is the Western Hemisphere Regional Warning Center (RWC) and the World Warning Agency (WWA) for the IUWDS. This paper discusses the IUWDS activities of the Boulder center since the last Solar-Terrestrial Predictions Workshop in 1984. SE-023 Fuller-Rowell, T.J., D. Rees, H.F. Parish, T.S. Virdi, P.J.S. Williams, and R.M. Johnson, Lower thermosphere coupling study: com- parison of observations with predictions of the University College London-Sheffield thermosphere-ionosphere model. Journal of Geophysical Research. 96(A2t 1181-1202 (1991). During the first Lower Thermosphere Coupling Study (LTCS), September 21-25, 1987, data were recorded from the incoherent scatter radar sites at EISCAT, Millstone Hill, Sondrestrom, and Arecibo. These experimental facilities measured ionospheric parame- ters (He, Te, Ti, and plasma velocity) in the E and the F regions which have been used to determine the E region neutral wind and infer the neutral temperature in the height range 100-150 km. Propagating tides are clearly visible in some of these parameters, and the latitude structure and phase variations with height indicate the presence of at least the (2,2) and (2,4) global tidal Hough modes. The influence of geomagnetic forcing is also clearly present at high latitudes. The University College London-Sheffield University three-dimensional coupled thermosphere-ionosphere model has been used to simulate this period of observation, by imposing tidal forcing at the lower boundary and magnetospheric forcing at high latitudes, in an attempt to interpret and understand the experimen- tal data. Model simulations are able to predict where the signature of a particular tidal mode is likely to be observed in the respective responses of the temperature and wind structure. The numerical simulations predict the range of observed tidal amplitudes at mid and high latitudes, provided the tidal forcing functions imposed near the lower boundary of the model are larger (400 m geopotential height variation) than those inferred from linear tidal models. At high latitudes, the semi-diurnal ion temperature response is driven by geomagnetic heating, rather than lower atmospheric tides and, as low as 110 km altitude, there is a large difference between ion and neutral temperatures during active conditions. Temperature and zonal wind tidal amplitudes observed at the low-latitude site of Areci- bo are consistently larger than those produced by any of the simulations. SE-024 GARCIA, H.A., and F. Farnik, Stereoscopic measurements of flares from PHOBOS and GOES. Solar Physics. 131: 137-148 (1991). A unique approach to observing the Sun stereoscopically in soft x-rays was afforded by the PHOBOS mission to Mars during 1989. Concurrent measurements of two flares from two widely separated spacecraft allowed us to obtain estimates of each flare's height above the solar surface. The requirement was that the flare had to be over the limb as observed by one spacecraft and on the visible disk as viewed by the other. The first flare occurred on March 4, when the active region was beyond the east limb as observed by GOES (at Earth), but on the disk as viewed by PHOBOS (at Mars). The second flare, on March 15, was on the disk for GOES, but beyond the west limb for PHOBOS. We believe that the same extraordinary active region, 5395, was responsible for both events. Soft x-ray photometers on each spacecraft contained two broad-band channels. The two-channel data were used to compute flare (assumed isothermal) plasma temperatures. The sharply peaked flare on March 4 indicated essentially identical maximum electron temperatures (-13 MK) at both spacecraft, confirming that the hottest plasma was indeed concentrated at the highest (unocculted) part of the loop. However, in the case of the long-duration March 15 flare, whose loop was in apparent upwards motion, the partially occulted flare indicated substantially cooler temperatures. This finding suggests that the hot core of this flare may have been below the limb, or that the partially occulted flux originated not from post-flare loops but from an independent, higher x-ray arch. The PHOBOS and GOES x-ray photometers were intercompared in July 1988, soon after the PHOBOS launch, to establish relative calibration parameters. SE-025 GRUBB, R.N., Transmission of solar wind velocity and g-map data from PRL to NOAA/SEL In Proceedings of the. Indo-U.S. Workshop on Interplanetary Scintillations and Solar Activity. Udaipur and Ahmedabad, India, February 1-5, 1988, R.V. Bhonsle, A. Bhatnagar, M. DRYER, S.K. Alurkar, A. Ambastha, and H.O. Vats (eds.), Physical Research Laboratory, Ahmedabad, 109-110(1991). No abstract. SE-026 HECKMAN, G.R., Terrestrial impacts of active region 5395 and implications for the remainder of solar cycle 22. In Solar- Terrestrial Predictions: Proceedings of a Workshop al Leura. Australia. October 16-20. 1989. Volume 2, R.J. Thompson, D.G. Cole, P.J. Wilkinson, M.A. Shea, D. Smart, and G. Heckman (eds.). U.S. Department of Commerce, Boulder, Colorado, 50-61 (1990). The rapid rise of solar cycle 22 (Hirman et al., 1988, 1989) and the occurrence of very intense solar activity in March of 1989, with attendant effects on earthly technical systems, raises interest in the potential occurrence of additional periods of very high solar 145 activity, including intense x-ray flare emission, geomagnetic storms, and solar particle events. Placing the March activity in a historical context, especially by comparing the potential level of solar cycle 22 to solar cycle 19, indicates that March may not be an isolated period of activity, but that several episodes, as intense as the March ones, and even greater in terms of effects of solar particle events, are likely in the next three to five years. Terrestrial effects of the March activity, including extended periods of communications diffi- culties, loss of all polar high frequency communications and over-the-horizon radar system operations for several days at a time, errors in navigation satellite systems, increased drag and attitude control in satellites, accelerated radiation degradation and intermittant oper- ating anomalies in satellites, and radiation impacts on manned space missions, are among the increased terrestrial effects to be ex- pected between now and 1995. Space environment forecasters and terrestrial systems operators can find exciting challenges in keeping systems operating with minimal losses over the next few years as cycle 22 makes its mark. SE-027 HILDNER, E., and M.S. GREER, Reliability of the McNish-Lincoln technique for predicting solar cycle amplitude in timing. In Solar-Terrestrial Predictions: Proceedings of a Workshop al LSiira, Australia. October 16-20, 12S9, Volume 1, R.J. Thompson, D.G. Cole, RJ. Wilkinson, M.A. Shea, D. Smart, and G. Heckman (eds.). U.S. Department of Commerce, Boulder, Colorado, 689-695 (1990). The McNish-Lincoln prediction technique, as currently implemented at the Space Environment Services Center of Space Environ- ment Laboratory, has been applied to each month of solar cycles 8 through 21. For each solar cycle, the resulting predictions of the amplitude and timing of the cycle's sunspot maximum have been compared with the actual, observed sunspot maximum for that cycle. McNish-Lincoln estimates of maximum smoothed sunspot numbers are found to be remarkable accurate and to improve with the pas- sage of time in the cycle. By contrast, the McNish-Lincoln technique gives poor estimates of the times of cycle maxima, and the accu- racy of these estimates does not improve appreciably with the passage of time in the cycle. SE-028 HILL, VJ., and J.W. HIRMAN, SESC Forecasters' Manual. In Solar-Terrestrial Predictions: Proceedings of a Workshop al Leura. Australia, October 16-20. 1989. Volume 1, R.J. Thompson, D.G. Cole, P.J. Wilkinson, M.A. Shea, D. Smart, and G. Heckman (eds.). U.S. Department of Commerce, Boulder, Colorado, 411-415 (1990). The Space Environment Services Center (SESC) Forecasters' Manual provides numeric guidance to the duty forecaster on the relationship between observed conditions or events and the expected, or predicted, levels of solar and geophysical activity. The objec- tive of the manual is to improve the quality of SESC forecasts. As a first step the forecasters' manual increases the forecasters' confi- dence in their forecasts by making relevant summary information readily available in a single document. The manual contains the best current information, as well as areas of incomplete knowledge and conflicts in statistical models. In order to increase its usefulness during periods of high solar activity, the manual is organized and formatted to help the forecaster find information quickly. It is a "living" document, changing and growing as new knowledge is added. SE-029 HIRMAN, J.W, and M.S. GREER, Prospective activity levels for solar cycle 22. In Solar-Terrestrial Predictions: Proceedings of a Workshop al Leura. Australia. October 16-20. 1989. Volume 1, R.J. Thompson, D.G. Cole, RJ. Wilkinson, M.A. Shea, D. Smart, and G. Heckman (eds.). U.S. Department of Commerce, Boulder, Colorado, 416-421 (1990). A major task for solar terrestrial forecasters is the prediction of major activity and quiet conditions for both short and long time scales. The national forecast centers of the IUWDS (International URSIGRAM and World Days Service) routinely produce short-term predictions and long-term outlooks for customers affected by changes in the space environment. We examine the limited data base of solar terrestrial activity records and develop guidance to forecasters making long-term outlooks. SE-030 JOSELYN, J.A., Forecasting magnetically quiet periods. In Solar-Terrestrial Predictions: Proceedings of a Workshop at Leura, Australia, October 16-20. 1989. Volume 1, R.J. Thompson, D.G. Cole, RJ. Wilkinson, M.A. Shea, D. Smart, and G. Heckman (eds.). U.S. Department of Commerce, Boulder, Colorado, 102-117 (1990). Most geomagnetic forecasting development has been directed toward storms because of their adverse effects on technological sys- tems. But forecasts of magnetically quiet periods are also useful. What are the solar wind signatures of quiet times? Based on daily Ap indices measured between 1976-1988 (13 years), there were 27 intervals lasting at least 7 days when Ap was 7 or less. These intervals were not uniformly distributed through the solar cycle, but were concentrated in the minimum and ascending phases of solar cycles 21 and 22. The solar wind associated with these intervals consisted to low to moderate speed plasma with above average density. Notably, the north/south component of the interplanetary magnetic field was small and variable (not predominantly northward). A majority of the time intervals contained a solar sector boundary, indicating that these quiet times were influenced by solar wind flows outward, along or neighboring a heliospheric current sheet. 146 SE-031 JOSE1YN, J.A., and B.T. Tsurutani, Geomagnetic sudden impulses and storm sudden commencements: A note on terminology. EOS, Transactions. American Geophysical Union. 71(47): 1808-9 (1990). No abstract. SE-032 Kahler, S., Coronal mass ejections and streamers associated with the new cycle active regions at solar minimum. The Astrophysical Journal. 378: 398-406 (1991). We use data from the coronagraph/polarimeter on the SMM spacecraft to examine the coronal streamers and coronal mass ejec- tions (CMEs) associated with the appearance of the high-latitude, new-cycle active regions at the beginning of solar cycle 22 in 1986 and 1987. Short-lived active regions, those lasting less than a disk passage, were not associated with streamers or CMEs. CMEs were generally associated with a high-latitude region only when another strong active region lay within -30° of the longitude of the high-la- titude region. The CMEs appeared to arise from magnetic connections between the high-latitude regions of opposite hemisphere. The development of streamers over the active regions appeared to be independent of the occurrence of CMEs. In some cases streamers formed over active regions with which no CMEs were observed, and in other cases CMEs were associated with regions with no overly- ing streamers. Streamers were also observed to survive CMEs associated with the underlying active regions. SE-033 Kamide, Y., and J. A. JOSELYN, Toward a standardized definition of geomagnetic sudden impulses and storm sudden commence- ments. Es§, 72(28): 300 (1991). No abstract. SE-034 Kiplinger, A.L., G. Labow, and L.E. Orwig, Contrasting effects among similar solar flares observed on 30 June 1989. In Max '91 /SMM Solar Flares: Observations and Theory. Proceedings of Max '91 Workshop No. 3, Estes Park, Colorado, June 3-7, 1990, R.M. Winglee and A.L. Kiplinger (eds.), University of Colorado, Boulder, pp. 210-233 (1991). We present comparisons of hard x-ray observations from the Hard X-Ray Burst Spectrometer (HXRBS) on the Solar Maximum Mission (SMM) satellite and high time resolution Ha observations obtained with the High Speed Digital Camera System in Boulder, Colorado. The observations were obtained near the end of the first Max '91 Campaign on 30 June 1989. This paper explores the opti- cal (Ha ) and hard x-ray properties of the two largest flares which were observed from the campaign target region (NOAA region 5569) on that day. Although the flares are nearly identical geometrically and temporally, the hard x-ray spectral behaviors are marked- ly different, as are the optical correlations with impulsive hard x-ray peaks. Impulsive flux peaks in hard x-rays have impulsive optical correlations in some but not all flaring areas and significant fluctuations are seen optically with no clear x-ray counterparts. It is specu- lated that evolving densities in flaring loops may contribute to differences in hard x-ray characteristics and optical responses between the two flares which occur less than three hours apart. SE-035 Kiplinger, A.L, E.M. Sion, and P. Szkody, A study of the ultraviolet evolution of U Geminorum between outbursts. The Astrophysical Journal. 366: 569-576 (1991). This paper examines the ultraviolet evolution of the dwarf nova U Gem from one outburst to the next. We present a series of seven sets of IUE observations that monitor the quiescent period of 22 days-103 days after outbursts (the seventh set is 2 days prior to the next outburst). An eighth set of observations obtained 75 days after the second outburst is included for comparison. In agreement with earlier studies, analyses of Lya profiles and 1200-2000 A continuum spectra during 103 days of quiescence are consistent with the presence of a 30,000 K white dwarf. We provide direct evidence that the UV flux levels continue to decrease throughout optical quiescence. These changes in flux appear consistent with the added presence of a hot component (perhaps the inner part of the disk or boundary layer) in addition to the white dwarf. Analyses of the absorption line spectra are also inconsistent with accretion of solar composition material onto the white dwarf. However, the Presence of Ny and Hen demands the existence of a line-formation region that is much hotter (Teff > 60,000 K) than the 30,000 K global photosphere. SE-036 KUNCHES, J.M., and C.N. CARPENTER, A forecaster's experience using Theo, an expert system. In Solar-Terrestrial Predictions: Proceedings of a Workshop al Leura. Australia. October 16-20. 1989. Volume 1, R.J. Thompson, D.G. Cole, P.J. Wilkinson, M.A. Shea, D. Smart, and G. Heckman (eds.). U.S. Department of Commerce, Boulder, Colorado, 482-486 (1990). Short-term (24 to 72 hours) probability forecasts of class M and class X flares are made daily by forecasters at the Space Environ- ment Services Center (SESC). An expert system, dubbed Theo, came on line in April 1987 to serve as an aid in making those fore- 147 casts. Theo relies on current sunspot data and knowledge of flare activity in the past 24 hours, and predicts class M and X flares in the next 24 hours. A partial verification was performed on Theo's flare forecasts made in the least-interactive way (so-called "default mode") for over 2 years of data, and the results are mixed. That same categorization applies to Theo's ease of use, speed, and user- friendliness. SE-037 KUNCHES, J.M., G.R. HECKMAN, E. HILDNER, and S.T. Suess, Solar Radiation Forecasting and Research to Support the Space Exploration Initiative. Special SEL Report, NOAA Space Environment Laboratory, Boulder, Colorado, 26 pp. (1991). No abstract. SE-038 LEINBACH, H., and R.N. GRUBB, Use of interplanetary scintillation (IPS) observations to forecast geomagnetic activity. In Solar-Terrestrial Predictions: Proceedings of a Workshop at Leura. Australia. October 16-20. 1989. Volume 2, R.J. Thompson, D.G. Cole, P.J. Wilkinson, M.A. Shea, D. Smart, and G. Heckman (eds.). U.S. Department of Commerce, Boulder, Colorado, 111-124(1990). Hewish and Duffett-Smith (1987) showed that all-sky maps of the scintillation of small-diameter extra-galactic radio sources have the potential for improving the accuracy in forecasting the time of onset of geomagnetic activity. Their statistics show that about about 35% of the IPS events that impact Earth may result in major magnetic activity (Ap a 40). Independent information on the direction and strength of the interplanetary magnetic field would be required to identify the geomagnetically important IPS events. The observ- ing cadence of mapping a given part of the sky once per day afforded by a single-station meridian-scan antenna is too infrequent for reliable forecasting. For example, Hewish and Duffett-Smith showed that only one all-sky map was available before impact of the dis- turbance at Earth in about 1/3 of the major magnetic storms in the period of August 1978-September 1979. At least two, and prefer- ably three IPS observatories, spaced several hours apart in longitude, are needed to provide maps at a frequency suitable for real-time forecasting purposes. SE-039 Lepping, R.P., L.F. Burlaga, B.T Tsurutani, K.W. Ogilvie, A.J. Lazarus, D.S. EVANS, and LW. Klein, The interaction of a very large interplanetary magnetic cloud with the magnetosphere and with cosmic rays. Journal of Geophysical Research. 96(A6): 9425-9438 (1991). A large interplanetary magnetic cloud has been observed in the mid-December 1982 data from ISEE 3. It is estimated to have a heliocentric radial extent of >0.4 AU, making it one of the largest magnetic clouds yet observed at 1 AU. The magnetic field mea- sured throughout the main portion of the cloud was fairly tightly confined to a plane as it changed direction by 174 degrees, while varying only moderately in magnitude. Throughout nearly the entire duration of the cloud's passage, IMP 8 was located in the Earth's dawn magnetosheath, providing observations of this cloud's interaction with the bow shock and magnetopause; the cloud is shown to maintain its solar wind characteristics during the interaction. Near the end of the cloud passage, at 0806 UT on December 17, ISEE 3 (and IMP 8 at nearly the same time) observed an oblique, fast forward interplanetary shock closely coincident in time with a geo- magnetic storm sudden commencement. The shock, moving much faster than the cloud (radial speeds of 700 and 390 km/s, respec- tively, on the average), was in the process of overtaking the cloud. The index Dst decreased monotonical'.y by —130 nT during the 2-day cloud passage by the Earth, and was well correlated with the Bz component of the interplanetary magnetic field. There was no significant decrease in the cosmic ray intensity recorded by ground-based neutron monitors at this time of rather strong, smoothly changing fields. However, a Forbush decrease did occur immediately after the interplanetary shock, during a period of significant field turbulence. Thus a large, smooth, interplanetary helical magnetic field configuration engulfing the Earth does not necessarily deflect cosmic rays sufficiently to cause a Forbush decrease, but there is a suggestion that such a decrease may be caused by particle scattering by turbulent magnetic fields. Finally, the field observations within the cloud are reasonably well described by a model developed by Burlaga (1988). SE-040 Martin, R.F, Jr., D.F. Johnson, and T.W. SPEISER, The energetic ion signature of an O-type neutral line in the geomagnetic tail. Advances in Space Research. 1 1(9): 203-206 (1991). An energetic ion signature is presented which has the potential for remote sensing of an O-type neutral line embedded in a current sheet. A source plasma with a tailward-flowing Kappa distribution yields a strongly non-Kappa distribution after interacting with the neutral line: sharp jumps, or ridges, occur in the velocity space distribution function f{vltVj) associated with both increases and de- creases in /. The jumps occur when orbits are reversed in the x-direction: a reversal causing initially earthward particles (low probabili- ty in the source distribution) to be observed results in a decrease in /, while a reversal cause initially tailward particles to be observed produces an increase in/. The reversals, and hence the jumps, occur at approximately constant values of perpendicular velocity in both the positive v« and negative v| half planes. The results were obtained using single particle simulations in a fixed magnetic field model. 148 SE-041 McINTOSH, P.S., Did sunspot maximum occur in 1989? Sky and Telescope. January: 21-23 (1991). No abstract. SE-042 Neary, J.E., L.C. Simonsen, H.H. SAUER, J.W. Wilson, and L.W. Townsend, Space Radiation Dose Analysis for Solar Flare of August 1989. NASA Technical Memorandum 4229, National Aeronautics and Space Administration, Washington, DC, 6 pp (1990). Potential dose and dose rate levels to astronauts in deep space are predicted for the solar flare event which occurred during the week of August 13, 1989. The Geostationary Operational Environmental Satellite (GOES-7) monitored the temporal development and energy characteristics of the protons emitted during this event. From these data, the differential fluence as a function of energy was obtained in order to analyze the flare using the baryon transport code developed at the Langley Research Center, BRYNTRN, which describes the interactions of incident protons in matter. Dose equivalent estimates for the skin, ocular lens, and vital organs for 0.5 to 20 g/cm2 of aluminum shielding were predicted. For relatively light shielding ( < 2 g/cm2), the skin and ocular lens 301-day exposure limits are exceeded within several hours of flare onset. The vital organ (5-cm depth) dose equivalent is exceeded only for the thinnest shield (0.5 g/cm2). Dose rates (rem/hr) for the skin, ocular lens, and vital organs are also computed. SE-043 Osherovich, VA., and H.A. GARCIA, Electric current in a unipolar sunspot with an untwisted field. Geophysical Research Letters. 17(12): 2273-2276 (1990). We apply the Return Flux (RF) sunspot model to a round, unipolar sunspot observed by H. Kawakami (1983). Solving the mag- netohydrostatic problem using the gas pressure deficit between the umbral and quiet-Sun atmospheres as a source function, we find a distribution of electric current density in an untwisted, unipolar sunspot as a function of height and radial distance from the sunspot center. Maximum electric current density is about 32 m A m"2 at the bottom of the sunspot. SE-044 Osherovich, V.A., and H.A. GARCIA, Development of an Advanced Sunspot Model. Final Report, NASA Contract 40 RA NR 903741. NOAA Space Environment Laboratory, Boulder, Colorado (1991). No abstract. SE-045 Pap, J.M., Spectral irradiance variability. Section 2 of Report by Commission 12: Radiation and Structure of the Solar Atmo- sphere. In Reports on Astronomy. XXIA, D. McNally (ed.), International Astronomical Union, The Netherlands, 85-87 (1991). No abstract. SE-046 Pap, J.M., J. London, and G.J. Rottman, Variability of solar Lyman alpha and solar total irradiance, Astronomy and Astrophysics. 245: 648-653 (1991). Variation of ultraviolet and total solar irradiance is investigated during the declining portion of solar cycle 21, through solar cycle minimum and into the rising portion of solar cycle 22. Both the Lyman alpha and total irradiance decrease during the declining phase of solar cycle 21 and increase with the growing new activity of solar cycle 22. The same changes are evident in a variety of solar activity indices, such as 10.7 cm radio flux Ca-K plage index and projected sunspot areas. However, while the total irradiance 10.6 cm radio flux, Ca-K plage index and projected sunspot areas each reach minimum levels in early 1985 with a flat background during the follow- ing two years, the Lyman alpha flux slowly decays to a brief minimum in mid-1986, around the time of magnetic solar minimum. SE-047 Pap, J.M., WH. Marquette, and R.F. DONNELLY, Modelling solar irradiances using ground-based measurements. Adv. Space Res.. 11(5): 271-274 (1991). The preliminary results of the photometry of Ca-K plage remnants show that during the fall of 1986 the remnants gave a signifi- cant contribution to the irradiance variations. The contribution of the plage remnants to the combined plage and remnant index was on average about 13% and it changed with time. SE-048 Pap, J.M., W.K Tobiska, and S.D. Bouwer, Periodicities of solar irradiance and solar activity indices, I. Solar Physics. 219: 165-189 (1990). Using a standard FFT time series analysis, our results show an 8-11 months periodicity in the solar total and UV irradiances, 10.7 cm radio flux, Ca-K plage index, and sunspot blocking function. The physical origin of this period is not known, but the evidence in 149 the results excludes the possibility that the observed period is a harmonic due to the FFT transform or detrending. Periods at 150-157 and 51 days are found in those solar data which are related to strong magnetic fields. The 51-day period is related to the emergence of new magnetic fields. A strong 13.5-day period is found in the total irradiance and projected areas of developing complex groups. This confirms those results (e.g., Donnelly et al., 1983, 1984; Bai, 1987, 1989) which show that "active centers" are located 180 degrees apart from each other. Our study also shows that the modulation of various solar data due to the 27-day solar rotation is more pro- nounced during the declining portion of the solar cycle than during the rising portion. This is because the active regions and their mag- netic fields are better organized and more long-lived during the maximum and declining portions of the solar cycle than during its rising portion. SE-049 Poquerusse, M„ and P.S. McINTOSH, Type III radio burst productivity of solar flares. Solar Physics. 130: 101-117 (1990). We study the statistical relationship between type III radio bursts and optical flares, using the comprehensive flare data base at the NOAA National Geophysical Data Center (Boulder, Colorado), and the radio observations obtained with the ARTEMIS multichannel spectrograph in Nancay (France), operating at 500-1000 MHz. At variance with previous results, we find that Type III probability of occurrence depends only weakly upon the spatial extension of the flare observed in Ha , but strongly upon its brightness. We also con- firm that type III probability increases with proximity to sunspots and with mass motions (surges and prominence activity); in addition, our statistical data are consistent with both relations holding at fixed flare brightness. Thus, some of the conditions favorable to type III occurrence are characteristic of compact flares, while others are characteristic of large and long-duration flares, which are often related to mass ejections. This apparent paradox suggests that particle acceleration and magnetic expansion are at work simultaneously in the ejection of electron streams out of flaring sites. SE-050 Sanahuja, B., A.M. Heras, V Domingo, and J. A. JOSELYN, Three solar filament disappearances associated with interplanetary low-energy particle events. Solar Physics. 134: 379-394 (1991). Three low-energy particle events (35-1600 keV) associated with interplanetary shocks, detected at 1 AU by ISEE-3, have been identified as originating in solar disappearing filaments instead of large flares. This increases to 14 the number of events of this kind presently known. The observational characteristics of these non-flare generated events are similar to the ones of the other 11 events already known (i.e., absence to type II or IV bursts, weak x-ray emission. Ha brightening in the surroundings of the filament disap- pearance, frequent presence of a double-ribbon event, slow propagation of the generated interplanetary shock, lack of shock decelera- tion). SE-051 SALTER, H.H., and K. O'Brien, Comparison of aircraft observations of radiation dose-equivalent rates with solar cosmic ray fluxes and with calculations, In Workshop on Ionizing Radiation Environment Models and Methods. April 16-18, 1991, Part I, Universi- ty of Alabama-Huntsville, 219-225 (1991) The period from August 12 through November 16, 1989, encompassed seven ground-level solar cosmic ray events. During these events, significant fluxes of protons greater than about 350 MeV were observed by instruments aboard the NOAA GOES-6 and -7 spacecraft and by dosimeters aboard Concorde SST aircraft operating between Europe and the United States. These events provided an opportunity to compare particle fluxes observed by the GOES instruments over energies from about >60 MeV to >800 MeV, transport code calculations of consequent dose -equivalent rates at SST altitudes, and in-situ, dose-equivalent measurements. The tim- ing discrepancies between estimates of the dose -equivalent rates as observed, and as calculated from fluxes obtained from typical re- ported measurements over the energy range up to several hundred MeV, underscore the importance of direct measurement in the 100-1000 MeV range in properly assessing solar cosmic ray effects deep within the atmosphere. Empirical calibration of the data from a Cerenkov Telescope (the HEPAD), aboard the GOES-6 spacecraft was performed. The fluxes > 350 and > 800 MeV determined from the HEPAD detectors agree well with a spectrum determined for the same time from Neutron Monitor data, and well describe the time profile of dose-equivalent rate observed at SST altitudes during the event. Initial calculations yield results which are a factor of 3 too high. SE-052 SAUER, H.H., and D.C. Wilkinson, Empirical synoptic mapping of the energetic particle environment at NOAA/TIROS altitudes (850 km). In Proceedings of \hs. ESA Workshop on Space Environment Analysis. Noordwijk, 9-12 October 1990, ESA-WPP-23, European Space Agency, Noordwijk, The Netherlands, paper 5.16, 5 pp (1991). The NOAA Space Environment Laboratory maintains instruments, the Space Environment Monitor (SEM), aboard the NOAA/ TIROS series of Sun-synchronous, low-altitude, polar-orbiting satellites. The SEM includes the Medium Energy Proton and Electron Detector (MEPED).which is that part of the SEM designed to measure the flux of energetic protons and electrons precipitating into or mirroring above the high-latitude atmosphere. Data from these detectors have been processed and averaged over 10 days, to provide adequate data sampling for producing synoptic average trapped and precipitating particle flux maps at satellite altitude (850 km) with a 150 spatial resolution of five degrees in both latitude and longitude. The processing involves the use of several approximations because of the limited directional information available and the lack of an on-board magnetometer. These approximations include: (1) definition of the top of the atmosphere to be at 120km, (2) use of a geomagnetic field model for pitch-angle and loss-cone-angle calculation, and (3) adoption of flat particle pitch-angle distributions within and outside the loss cone. The procedures by which the data are processed in the construction of the maps are described and are illustrated by examples obtained from data of the March 1989 period of extreme geomagnetic activity. SE-053 Simonsen, L.C., J.E. Nealy, H.H. SAUER, and L.W. Townsend, Solar Flare Protection for Manned Lunar Missions: Analysis of the October 1989 Proton Flare Event. SAE Technical Paper 911351, SAE International, Warrendale, PA, 11 pp (1991). Several large solar proton events occurred in the latter half of 1989. For a moderately shielded spacecraft in free space, the poten- tial exposure would have been greatest for the flare which occurred between October 19 to 27, 1989. This flare was comparable to the large flare event of August 1972. The temporal variations of the proton energy spectra at approximately 1 AU were monitored by the GOES-7 satellite. These data, recorded and processed at the NOAA-Boulder Space Environment Laboratory, provide the oppor- tunity to analyze dose rates and cumulative doses which might be incurred by astronauts in transit to, or on, the moon. Of particular importance in such an event is the time development of exposure in the early phases of the flare, for which dose rates may range over many orders of magnitude in the first few hours. Consequently, special attention is given to the early time variation of the dose rate. The cumulative dose as a function of time for the entire event is also predicted. In addition to basic shield calculations, dose rate contours are constructed for flare shelters in free space and on the lunar surface. For longer duration lunar missions, the impact of such a flare exposure is assessed in relation to the predicted steady dose rate of the galactic cosmic rays. SE-054 Smith, D.F, and A.O. Benz, A mechanism for producing plasma radiation in the gigaherz range by precipitating high-energy pro- tons. Solai Ehysics, 131: 351-361 (1991). Gamma-ray observations are discussed to determine the density of protons of about 1 MeV precipitating to the photosphere. It is shown that Coulomb collisions will produce a positive slope in the proton distribution for energies less than 0.1 MeV for traversed column depths greater than 1018 cm"2. This could lead to plasma wave emission and radiation near the plasma frequency for densities -3.1 x 1010 cm"3 and temperatures -4.0 x 104 K where collisional and collisionless damping of the plasma waves is sufficiently weak. It is expected that these conditions will only be satisfied sporadically, which leads to stationary radio emission limited in frequen- cy and time. Recent radio observations of impulsive phase non-drifting patches in the 1-3 GHz range with duration 2-4 s are pres- ented which could be produced by this mechanism. SE-055 Smith, D.F, and S.H. Brecht, Coronal proton transport in the presence of Alfven waves and implications for gamma-ray burst models. The Astrophysical Journal. 373: 289-293 (1991). The transport of fast ( > 10 MeV) protons in the corona is considered when their density and anisotropy are sufficiently large to excite Alfven waves. It is shown that, for coronal propagation lengths of 3 x lO^m or 5 x 108cm, Alfven waves scatter the protons and make them almost isotropic. The Alfven wave instability remains in a marginally stable state in which the proton anisotropy is just large enough to excite Alfven waves to a level which would eliminate any greater anisotropy. As a result the proton path lengths are 6-65 times larger than in the absence of Alfven waves and their mean free paths are 3 x 106 - 4 x 107 cm, i.e., the protons are well contained. For proton coronal propagation lengths of 3 x 108 or 5 x 108 cm, loop densities of at least 4 x 1010cm are required for a magnetic field of 100 G for the 1980 June 7 flare. In general, only loops of high density and/or low magnetic field are consistent with the other observations of this flare. This theory is compared with the theory of Bespalov, Zaitsev, and Stepanov. Similar arguments and results can be made for any flare with impulsive time scales - 10 s or less. SE-056 SMITH, Z., and M. DRYER, MHD study of temporal and spatial evolution of simulated interplanetary shocks in the ecliptic plane. Solar Physics. 129: 387-405 (1990). We utilize a 2'/2-D MHD time-dependent model to perform a parametric study of interplanetary shock propagation to 1 AU. The input conditions are represented by the following variables: (1) initial shock velocity, (2) duration of the driving pulse, and (3) width of the pulse at the near-Sun position (18 solar radii). The total net energy added to the solar wind was calculated for each pulse. The forward shock's travel time to, and the peak dynamic pressure at, 1 AU as a function of location at the shock front have been studied over a range of total input pulse energies from 1029 to 1032 ergs. For input pulses with modest angular width and temporal duration, we find that the propagation of the resulting interplanetary fast forward shock waves depends primarily upon the net input energy. The dependence of the transit time upon energy is a power law with a -1/3 index which corresponds to the classical, piston-driven case. Reverse shocks are also formed behind all but the lowest energy shocks. Their properties, although also a function of input energy, 151 depend upon the specific values of the input pulse shock velocity, width, and duration. We also briefly discuss the propagation of the shocks out to 1 AU, and the conditions for which the interplanetary shocks depart from being symmetric about the input pulse central meridian due to magnetic and dynamic effects. SE-057 SMITH, Z., and M. DRYER, Numerical simulations of high-speed solar wind streams within 1 AU and their signatures at 1 AU. Solar Phvsics. 131: 363-383(1991). A parametric study of the evolution within, and signatures at 1 AU of high-speed streams is performed with the use of a MHD, P.Vi-D, time-dependent model. This study is an extension of an earlier one by Smith and Dryer (1990), who examined the ecliptic plane consequences of relatively short-duration, energetic solar disturbances. The present study examines both the erupting and corotating parts of long-duration, high-speed streams characteristic of coronal hole flows. By examining the variation of the simulated plasma velocity, density, temperature, and magnetic field at 1 AU, we are able to provide some insight into the identification of the solar sources of interplanetary disturbances. We present and discuss two definitions for angle locating the solar source of interplanetary dis- turbances at 1 AU. We apply our results to the suggestion by Hewish (1988) that low-latitude coronal holes are suitably positioned to be the sources of major geomagnetic storms when the holes are in the eastern half of the solar hemisphere at the time of the com- mencement of the storm. Our results indicate that, for these cases, the streams emanating from within the hole must be very fast, greater than 1000 km s"1, or very wide, greater than 60°, at the inner boundary of 18 solar radii in our simulation. SE-058 SPEICH, D.M., J.J. Nelson, J.P. licata, and A.K. Tolbert, The 1980 Solar Maximum Mission event listing. NASA Technical Memorandum 4287, N91-27087, Goddard Space Flight Center, Greenbelt, MD, 433 pp (1991). No abstract. SE-059 SPEISER, T.W., The geomagnetic tail. In Geomagnetism. Vol. 4, ISBN 0-12-378674-6, Academic Press, Ltd., 335-401 (1991). No abstract. SE-060 SPEISER, TW, Particle motion in the tail current sheet. Advances in Space Research. 11(9): 151-159 (1991). Theory of particle motion in current sheets is reviewed. For small, approximately constant normal magnetic field, B^ particles oscillate about the current sheet and "live" within the sheet for one-half gyroperiod based on 1^. This lifetime replaces the mean colli- sion time in the Lorentzian conductivity and thus gives rise to the concept of an inertial (or gyro-) conductivity. A substorm model by Coroniti 111 utilizes this conductivity to allow reconnection to proceed without anomalous processes due to wave-particle interactions. Chaotic particle orbits may at times be important to the dynamics, depending on parameters such as particle energy, current sheet thickness, and field line curvature. A current sheet model with neutral line predicts a ridge structure and asymmetries in the distribu- tion function. Ion distributions near the plasma sheet boundary layer, during the CDAW 6 interval, are consistent with the model pre- dictions. In recent studies by Mitchell et al. /27/ and Williams et al. /26/, the major current carriers during the growth phase of a sub- storm were found to be adiabatic electrons < 1 keV, but just before a current disruption event, the tail current was mainly carried by energetic ions undergoing current sheet oscillation. SE-061 SPEISER, TW, P.B. Dusenbery, R.F. Martin, Jr., and D.J. Williams, Particle orbits in magnetospheric current sheets: Accelerated flows, neutral line signature, and transitions to chaos. In Modeling Magnetosphere Plasma Processes. Geophysical Monograph 62. American Geophysical Union, 71-79 (1991). Theory of particle motion in current sheets is reviewed. For small, approximately constant normal magnetic field, Bz, particles oscillate about the current sheet and "live" within the sheet for one-half gyroperiod based on Bz. This lifetime replaces the mean colli- sion time in the Lorentzian conductivity and thus gives rise to the concept of an inertial (or gyro-) conductivity. A substorm model by Coroniti (1985) utilizes this conductivity to allow reconnection to proceed without anomalous processes due to wave-particle interac- tions. Chaotic particle orbits may at times be important to the dynamics, depending on parameters such as particle energy, current sheet thickness, and field line curvature. A current sheet model with neutral line predicts a ridge structure and asymmetries in the distribution function. Observed ion distributions near the plasma sheet boundary layer, during the CDAW 6 interval, are consistent with the model predictions. 152 SE-062 Tappin, S.J., and M. DRYER, MHD modelling and g-maps. In Proceedings of Ihe. Indo-U.S. Workshop on Interplanetary Scintillations and Solar Activity. Udaipur and Ahmedabad, India, February 1-5, 1988, R.V Bhonsle, A. Bhatnagar, M. DRYER, S.K. Alurkar, A. Ambastha, and H.O. Vats (eds.), Physical Research Laboratory, Ahmedabad, 157-161 (1991). In this paper we describe the merging of IPS simulations with 3-dimensional MHD modelling. Much of the material covered here will be described in more detail in a paper describing the modelling system by Tappin et al. 1988. Possibilities for using the system in an operational way are covered. SE-063 Thompson, R.J., D.G. Cole, P.J. Wilkinson, M.A. Shea, D. Smart and G. HECKMAN (eds.) Solar-Terrestrial Predictions: Proceedings of a Workshop at Leura, Australia, October 16-20, 1989, Special 2- Volume publication, PB91-197079/PB91-197087, U.S. Department of Commerce, NOAA, Boulder, Colorado (1990). No abstract. SE-064 Thompson, R.J., E.C. Willock, and PS. McINTOSH, Analysis and Display of Solar Synoptic Maps at IPS. Technical Report IPS TR-91-02, IPS Radio and Space Services, Chatswood, N.S.W, Australia, 19 pp. This report outlines the facilities which have been established at IPS Radio and Space Services to Analyse and to display solar syn- optic maps and associated data. The project to develop these facilities was undertaken during 1989-1990 during a six month visit to IPS of Patrick Mcintosh from the Space Environment Laboratory in Boulder, USA. The facilities have been constructed to provide flexible means by which the large-scale and long-term evolution of solar features can be studied. Such studies offer the prospects of important improvements to our ability to forecast the solar-terrestrial environment over medium-to-long timescales (from weeks to years). Such improvements would prove of major benefit to IPS and its clients. SE-065 Wei, F., and M. DRYER, Propagation of solar flare-associated interplanetary shock waves in the heliospheric meridional plane. Solar Physics. 132: 373-394 (1991). We have analyzed 149 flare -associated shock wave events based on interplanetary scintillation (IPS) observational data. All of the flare-associated shock waves tend to propagate toward the low-latitude region near the solar equator for flares that are located in both the solar northern and southern hemispheres. Also, the fastest propagation directions tend toward the heliospheric current sheet near 1 AU. We suggest that this tendency is caused by the dynamic action of near-Sun magnetic forces on the ejected coronal plasma that traverses the helmet-like magnetic topologies near the Sun outward to the classical topology that is essentially parallel to the heliospheric current sheet. SE-066 Wilkinson, P.J., and PS. McINTOSH, Outstanding solar events of the present solar cycle and their effects. In Australian National Research Expeditions (AN ARE) Research Notes 80. Gary Burns (ed.), Antarctic Division, Dept. of the Arts, Sport, the Environ- ment, Tourism, and Territories, Kingston, Tasmania, 113-127 (1991). The current cycle of sunspot activity (#22) is near its maximum. Solar flare activity in 1989 produced the most serious terrestrial effects since the record cycle 19 of the International Geophysical Year (1957-58). Events in the period August-October 1989 pro- duced relativistic particles capable of penetrating Earth's atmosphere to the ground. These rare Ground Level Enhancements (GLEs) were among the most intense on record and were a hazard for supersonic transport and spacecraft. The intense geomagnetic storm associated with unprecedented solar flare activity in March is now accepted as the cause of a major disruption to the electric power distribution system in Quebec. Aurora with this storm were reported at tropical latitudes, including the north coast of Australia. However, on other occasions during the year geomagnetic storms, particles, and ionospheric activity were poorly correlated with the sunspot number, radio flux, or the frequency and intensity of the x-ray fluxes. SE-067 Wilson, PR., and PS. McINTOSH, The origin of the large-scale fields. In Solar-Terrestrial Predictions: Proceedings of a Workshop at Leura. Australia. October 16-20. 1989. Volume 1, R.J. Thompson, D.G. Cole, P.J. Wilkinson, M.A. Shea, D. Smart, and G Heckman (eds.). U.S. Department of Commerce, Boulder, Colorado, 650-657 (1990). A basic assumption of current models of the solar surface magnetic fields is that the large-scale fields, including the polar fields, arise primarily from the decay of the fields of active regions. However, we here report recent observations of the development of both large-scale and active regions fields early in cycles 20 and 22 which are inconsistent with this assumption and we consider the implica- tions of these results. Among them is the possibility of predicting large-scale aspects of solar activity, including recurrent coronal holes. 153 SE-068 Winglee, R.M., G.A. Dulk, PL. BORNMANN, and J.C. Brown, Interrelation of soft and hard x-ray emissions during solar flares. II. Simulation model. The Astrophysical Journal. 375: 382-403 (1991). Recent observations indicated that quasi-static electric fields may be important in the acceleration of the electrons responsible for hard x-ray emissions during impulsive solar flares. Quasi-static fields are also required to drive and to close the currents carried by the accelerated electrons. Two-dimensional (three velocity) electrostatic particle simulations are presented which incorporate the effects of those fields on the particle dynamics as well as those arising from wave-particle interactions induced by the accelerated particles. In the model, the particle acceleration is initiated by a cross-field current in the corona. Because of the limited cross-field mobility of par- ticles in a collisionless plasma, this current can only be closed in the chromosphere where cross-field transport is aided by collisions. As a result, strong quasi-static electric fields are set up which produce strong downward acceleration of electrons in the primary current region. On adjacent field lines, electrons are accelerated up into the corona to provide a return current, but because of the relatively large cross-section of the return current region, the electrons in this region remain relatively low in energy. The induced perpendicular currents are initially provided by the ions, but, as the chromosphere becomes heated by precipitation of energetic electrons, perpendic- ular electron currents become important, and these currents in turn modify the particle acceleration in the latter part of the flare. The calculated properties of the soft and hard x-ray and microwave emissions from such a system have the following properties: (1) acceler- ation by quasi-static electric fields and heating via wave-particle interactions produces electron distributions with a broken-power law, similar to those inferred from hard x-ray spectra; (2) heating of the ambient plasma gives rise to a region of hot plasma which propa- gates down to the chromosphere at about the ion sound speed; (3) the arrival of this hot plasma region in the chromosphere causes the hard x-ray flux to peak due to modification of the cross-field conductivity so that the passage of soft x-ray fronts and the hard x-ray peak are expected to be correlated; (4) the perpendicular heating of coronal electrons is relatively slow, and this can give rise to the observed delay of the microwave peak relative to the hard x-ray peak; (5) heavy ions are preferentially accelerated across the fields as the cross-field currents form, leading to enhancements of heavy ion abundances in the primary current region; this enhanced heavy ion abundance may account for those inferred from soft x-ray line emissions; (6) the ions in the primary current region are then acceler- ated by the same electric fields accelerating the hard x-ray electrons downward; and (7) this parallel and perpendicular acceleration can give rise to Doppler shifts in soft x-ray line emissions similar to those seen during disk and limb flares. SE-069 Winglee, R.M., A.L. Kiplinger, D.M. Zarro, G.A. Dulk, and J.R. Lemen, Interrelation of soft and hard x-ray emissions during solar flares. I. Observations. The Astrophysical Journal. 375: 366-381 (1991). Simultaneous observations of hard x-rays and of soft x-ray line emissions at high time resolution ( =6 s) from the Solar Maximum Mission (SMM) are used to determine the interrelation between the acceleration and heating of electrons and ions during impulsive solar flares. The study involves five flares (three disk and two limb flares). It is shown that, for all the flares, the hard x-rays have a power-law spectrum that breaks down during the rise phase and the beginning of the decay phase, after which the spectrum changes to either a single power law or a power law that breaks up at high energies. The characteristics of the soft x-rays depend en the flare position. For the three disk flares, the line emissions show a blueshifted component (arising from upward acceleration of ions into the corona), with the maximum inferred velocity reaching its peak value during the decay phase in association with the disappearance of the (downward) break in the hard x-ray spectrum. For limb flares the soft x-ray line emissions show only a nonthermally broadened stationary component (arising from acceleration and heating perpendicular to the magnetic field); this broadening reaches a maximum at the hard ( > 50 keV) x-ray peak rather than during the decay phase. These observations are not consistent with models where the chromospheric outflow is driven by explosive heating since both the blueshifts and broadening are predicted to have the same depen- dence on the hard x-ray flux. It is argued instead that small-scale, quasi-static electric fields are important for determining the accelera- tion of the x-ray-producing electrons and the outflowing chromospheric ions. These electric fields provide bulk acceleration of energet- ic electrons into the chromosphere (with the electric potential being of the order of the break energy). At the same time, they acceler- ate ions across the field lines and out into the corona. The different behavior of the blueshifts and broadening relative to the hard x-ray emissions is attributed to differences in scale lengths parallel and perpendicular to the magnetic field. SE-070 Wu, S.T, M. DRYER, and S.M. Han, Recent development on the numerical simulation of astrogeophysical flows. In Proceedings of ihe. Indo-U.S. Workshop on Interplanetary Scintillations and Solar Activity. Udaipur and Ahmedabad, India, February 1-5, 1988, R.V. Bhonsle, A. Bhatnagar, M. DRYER, S.K. Alurkar, A. Ambastha, and H.O. Vats (eds.). Physical Research Laboratory, Ahmedabad, 111-113(1991). In this paper we present the recent developments of numerical simulation models for astrogeophysical flows, in particular, the propagation of solar disturbances in the heliospheric space. SE-071 Wu, S.T, M.T. Song, P.C.H. Martens, and M. DRYER, Shear-induced instability and arch filament eruption: A mag- netohydrodynamic (MHD) numerical simulation. Solar Physics. 134: 353-377 (1991). We investigate, via a two-dimensional (nonplanar) MHD simulation, a situation wherein a bipolar magnetic field embedded in a stratified solar atmosphere (i.e., arch-filament-like structure) undergoes symmetrical shear motion at the footpoints. It was found that 154 the vertical plasma flow velocities grow exponentially leading to a new type of global MHD-instability that could be characterized as a "dynamic shearing instability," with a growth rate of about »8 VAa, where VA is the average Alfven speed and a'1 is the characteristic length scale. The growth rate grows almost linearly until it reaches the same order of magnitude as the Alfven speed. Then a non- linear MHD instability occurs beyond this point. This simulation indicates the following physical consequences: the central loops are pinched by opposing Lorentz forces, and the outer closed loops stretch upward with the vertically rising mass flow. This instability may apply to arch filament eruptions (AFE) and coronal mass ejections (CMEs). To illustrate the nonlinear dynamical shearing instability, a numerical example is given for three different values of the plasma beta that span several orders of magnitude. The numerical results were analyzed using a linearized asymptotic approach in which an analytical approximate solution for velocity growth is presented. Finally, this theoretical model is applied to describe the arch filament eruption as well as CMEs. SE-072 Yeh, T, and S.T Wu, Model calculations of the rising motions of a prominence loop. Solar Physics. 132: 335-351 (1991). Model calculations are presented for the rising motion of the top section of a prominence loop, which is represented by a straight flux rope immersed in a coronal medium permeated with a bipolar magnetic field. Initially the prominence is at rest, in equilibrium with the surrounding coronal medium. When the magnetic monopoles that account for the source current for the bipolar field strengthen, the upward hydromagnetic buoyancy force overcomes the downward gravitational force so that the prominence is initiated into rising motion. The illustrative examples show that prominences can move away from the solar surface by the action of the hydromagnetic buoyancy force, which is preponderant with the diamagnetic force due to the current carried by the prominence inter- acting with the coronal magnetic field produced by the photospheric currents, if the changes in the photospheric magnetic field are sufficiently large. 155 WAVE PROPAGATION LABORATORY WP-001 Alldredge, A.L., and P. McGillivary. The attachment probabilities of marine snow and their implications for particle coagulation in the ocean. Deep-Sea Research, 38(4):431-443 (1991). The rate at which suspended particles in the ocean coagulate to form larger, more rapidly sinking aggregates is directly related to the frequency with which the particles stick together once they have collided. The attachment probabilities of marine macroscopic detrital aggregates, known as marine snow, were determined by video recording and analyzing individual particle-particle interactions between 660 pairs of aggregates colliding together via gravitational settlement Attachment probabilities of natural marine aggregates in the size range from 0.2 to 7.6 mm are the highest yet reported for natural particles, ranging from 0.609 (60% of collisions result in attachment) for amorphous detrital aggregates to 0.88 for flocculated diatoms. Attachment probabilities increase with increasing particle volume, surface area of contact and collision velocity. Large size and surface complexity resulting in multi-point contact between colliding particles and the abundance of sticky, microbially-produced exopolymers on the aggregate surfaces probably contribute to high aggregation efficiencies. The high attachment probabilities of suspended macroaggregates suggest that the rate of aggregation of organic particles by physical coagulation in the ocean may be many times higher than previously predicted. WP-002 Bahar, E. Acoustic backscatter cross sections for rough sea surface excited from above and below the air-water interface. Journal of the Acoustical Society of America, 90( 1 ):433-440 (1991). Acoustic backscatter cross sections (normalized scattered pressure intensities) are evaluated for rough seas using a unified full-wave approach that accounts for specular point scatter and Bragg scatter in a self-consistent manner. Thus the two-scale model of the sea surface is not used in these investigations. Different surface wind speeds are considered. The full-wave cross sections are shown to be significantly different for excitations from above or below the air-water interface. The full-wave solutions are compared with the corresponding physical- acoustic and small-perturbation solutions. WP-003 Bahar, E. Acoustic scattering by two-dimensionally rough interfaces between dissipative acoustic media — full wave, physical acoustics, and perturbation solutions. Journal of the Acoustical Society of America, 89(1): 19-26 (1991). Explicit expressions for the acoustic pressure and velocity scattered by two-dimensionally rough surfaces are derived using a full-wave approach. The conditions under which these solutions merge with the physical acoustic and small perturbation solutions in the high- and low-frequency limits are given. The acoustic media on both sides of the rough interface are characterized by their bulk modulus, equilibrium density, and relaxation time (to account for dissipation); the Dirichlet and Neumann boundary conditions are treated as special cases. The closed-form full-wave expressions for the surface element scattering coefficients are significantly different for these special cases. However, the corresponding physical optics solutions differ only in the sign of the acoustic reflection coefficient The full-wave solution can be applied to composite surfaces with a broad range of roughness scales. Since it accounts for specular point and diffuse scattering in a unified self-consistent manner, there is no need to adopt a two-scale model of the rough surface. Thus the full-wave expressions for the rough surface scattered fields are also more suitable for application to broadband (transient) excitation problems and for the solution of inverse problems. WP-004 Bahar, E. Examination of full-wave solutions and 'exact numerical results' for one-dimensional slightly rough surfaces. Journal of Geophysical Research, 96(C9): 17123-17131 (1991). In this paper, the principal elements of the full-wave solution and its direct analytical links to the physical-optics and small-perturbation solutions are reviewed succinctly. Thus a two-step analytical procedure that transforms Rice's "first-order" small-perturbation solution into the physical-optics solution is prescribed. Questions of convergence raised by Rice himself are also addressed since the small-perturbation solution (when applied to random rough surfaces) diverges as the slope parameter becomes smaller and smaller. Furthermore, it is shown that the "exact numerical results" based on the moments method do not include the diffraction term, while the corresponding full-wave results, used for comparison do include the diffraction term. No true comparisons can be made between the full-wave solution and the small- perturbation solution unless the excitations assumed in both cases are the same and unless the diffraction term is not added to the full-wave solution for the diffusely scattered field. 156 WP-005 Bahar, E. Full wave solutions for the scattering of acoustic waves excited by arbitrary source distributions in irregular layered media. Journal of Wave Motion, 12:301-314 (1990). Generalized Fourier transforms for the acoustic pressure and velocity are derived for propagation in irregular layered media. They provide a basis for the complete expansion of three-dimensional acoustic fields excited by arbitrary source distributions. The height above a reference plane of the interface between two semi-infinite media, the adiabatic bulk modulus, the equilibrium density, and the viscosity of the media above and below the interface are assumed to vary along one coordinate variable in the reference plane. The equations of continuity and force in conjunction with the associated boundary conditions at the irregular interface are converted into rigorous first-order coupled differential (telegraphists') equations for the forward- and backward-propagating wave amplitudes. The differential scattering coefficients are shown to satisfy the reciprocity relationships. The telegraphists' equations arc solved interactively to derive closed-form solutions for the singly scattered radiation and surface fields excited by acoustic sources at large distances from the irregular interface. The full wave solutions account for specular-point as well as diffuse scattering in a unified self-consistent manner. WP-006 BANTA R.M., and LJD. OLIVIER- Doppler lidar observations of air flow in the Grand Canyon. Proceedings, 84th Annual Meeting and Exhibition, Vancouver, British Columbia, Canada, June 16-21, 1991. Air and Waste Management Association, Pittsburgh, PA Vol. IL Paper 91-47.11, 16 pp. (1991). No abstract. WP-007 BANTA, R.M., LX). OLIVIER, and E.T. Holloway. Doppler lidar observations of a rotational convective smoke column. Proceedings, 1 1th Conference on Fire and Forest Meteorology - Computer Applications in Research and Management, Missoula, MT, April 16-19, 1991. American Meteorological Society, Boston, MA, 412-418 (1991). The Doppler lidar of NOAA/ERL's Wave Propagation Laboratory (WPL) observed a prescribed forest fire that was ignited in the township of Battersby, Ontario, Canada on 12 August 1988. During the first hour of the fire the lidar saw the smoke column rise nearly straight up to a height of over 1.5 km above ground in response to very light and variable environmental winds below that level. After the first hour of the burn, stronger southwesterly flow in the boundary layer bent the smoke plume over towards the lidar. During the initial vertical-rise phase of the convective column the lidar observed a strong rotational signature in horizontal scans of the radial velocity. The vorticity of the column is estimated to be lO2 s'\ and this agrees with the rotational rate estimated from a time lapse video cassette recording of the convective column taken from the lidar site. Lidar data were also used to estimate convergence into the column and vertical velocities (w) within the column. Peak w values were estimated to exceed 15 ms'1 at the base of the cumulus congestus cloud that capped the column. We performed MIE backscatttering calculations using aircraft-observed size distributions of smoke particles in the smoke plume. The calculations indicated that the major contribution to backscatter came from particles 1.0-3.0 um in diameter, but that the extremely large numbers of small (0.1-1.0 um diameter) particles and a smaller number of larger (3.0-30.0 um diameter) particles also produced strong contributions to the returns. WP-008 BANTA R.M., LJD. OLIVIER, and WJD. NEFF. Flow in the Crand Canyon and other valleys as revealed by Doppler lidar. Preprints, 7th Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, MA, J210-J213 (1991). No abstract. WP-009 BEDARD, AJ., JR. The measurement of sonic boom waveforms and propagation characteristics: techniques and challenges. Preprints, 13th AIAA Aeroacoustics Conference, Tallahassee, FL, October 22-24, 1990. American Institute of Aeronautics and Astronautics, Washington, DC (1990). The measurement of sonic boom waveforms in a turbulent atmosphere with complex non-stationary profiles and three-dimensional structures of temperature, wind, and humidity presents a difficult challenge. Representative measurements are critical for the verification of not only numerical predictive models but also of concepts for sonic boom alleviation. Variations in aircraft flight paths and speed as well as organized atmospheric structures in the acoustic propagation path further complicate this measurement problem. This paper reviews past experimental approaches, pointing out measurement needs; suggests possibilities in the form of new instruments, processing and concepts that could be applied; and indicates the opportunities that exist or are being planned for facilities and networks that could provide data for initializing predictive models on a nationwide basis, or provide sites for field experiments. 157 WP-010 BEDARD, AJ., JR., and W. Cunningham. Potential aircraft hazards in the vicinity of convectivc clouds: A review from the perspective of a scale model study. Preprints, 4th International Conference on Aviation Weather Systems, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, MA, 66-70 (1991). In recent years a considerable amount of work has addressed the hazards posed by low-level wind shear. However, the region near the tops of convective clouds as well as lee side instabilities can also be hazardous. This paper addresses the interactions between convective clouds and environmental fields, including stable layers and vertical wind shear. The disturbances observed or deduced to occur near convective clouds range from wave fields (both propagating and stationary) to organized Kaman vortex-like instabilities. An aircraft accident has been attributed to a stationary wave system in the lee of convection. Specifically, a solid obstacle was used in a case study to model a convective cloud; results indicated that a lee wave downstream of a penetrating updraft caused the hazard (e.g., Keller et al. 19&3). We performed scale-model studies of buoyant columns interacting with shear layers at the University of Colorado at Boulder. We compared model results with observed and computed disturbances for a variety of penetrative convection and environmental interactions. WP-011 BODHAINE, B.A., JJ. DELUISL J.F. BOATMAN, Y. KIM, DJL. WELLMAN, R.L. GUNTER, MJ. POST, RE. CUPP, G.T. McNice, J.M. Rosen, PJ. Sheridan, RC. Schnell, D.M. Garvey, Ail. Wade, and RC. Steinhoff. The second Front Range lidar, aircraft, and balloon experiment NOAA Data Report ERL CMDL-8, 142 pp. (1991). The Front Range Lidar, Aircraft, and Balloon (FRLAB) experiment was performed near Boulder, Colorado, on July 26, 1989, and the second FRLAB experiment was performed on May 23-24, 1990. The purpose of the experiment was to make simultaneous measurements of aerosol profiles in the atmosphere using C02, ruby, Nd:YAG, and ER:Glass lidars; airborne nephelometer, condensation nucleus (CN) counter, and aethalometer; and balloonbome backscattersonde. The data allows a direct comparison between several diverse types of instruments as well as a quantitatively consistent evaluation of the amount of non-Rayleigh scattering occurring in the tropospheric clean region where lidar profiles are often normalized. WP-012 Bond, N.A., and MA. SHAPIRO. Aircraft observations of developing polar lows over the Gulf of Alaska. Preprints, 1st International Symposium on Winter Storms, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, MA, 315-320 (1991). No abstract. WP-013 Bowdle, D.A., J. Rothermel, J.M. Vaughan, D.W. Brown, and M.J. POST. Aerosol backscatter measurements at 10.6 micrometers with airborne and ground-based C02 Doppler lidars over the Colorado high plains. 1. Lidar intercomparison. Journal of Geophysical Research, 96(D3):5327-5335 (1991). An airborne continuous wave (CW) focused C02 Doppler lidar and a ground-based pulsed G02 Doppler lidar were used to obtain seven pairs of comparative measurements of tropospheric aerosol backscatter profiles at 10.6 urn wavelength, near Denver, Colorado, during a 20- day period in July 1982. In regions of uniform backscatter the two lidars show good agreement, with differences usually less than approximately 50% near 8-km altitude and less than a factor of 2 or 3 elsewhere but with pulsed lidar often lower than the CW lidar. Near sharp backscatter gradients, the two lidars show poorer agreement, with the pulsed lidar usually higher than the CW lidar. Most discrepancies arise from a combination of atmospheric factors and instrument factors, particularly small-scale areal and temporal backscatter heterogeneity above the planetary boundary layer, unusually large-scale vertical backscatter structure in the upper troposphere and lower stratosphere, and differences in the spatial resolution, detection threshold, and noise estimation for the two lidars. WP-014 Bowdle, D.A., J. Rothermel, J.M. Vaughan, and M.J. POST. Aerosol backscatter measurements at 10.6 micrometers with airborne and ground-based O02 Doppler lidars over the Colorado high plains. 2. Backscatter structure. Journal of Geophysical Research, 96(D3):5337-5344(1991). Measurements of tropospheric aerosol volume backscatter coefficients at 10.6-um wavelength were obtained with airborne continuous wave and ground-based pulsed C02 Doppler lidars over the Colorado high plains during a 20-day period in summer 1982. A persistent "background" layer was found between 6- and 10-km altitude, with a generally uniform backscatter mixing ratio of approximately 10"'° m2 kg'1 sr"1. The upper boundary of this background layer varied with the tropopause height; the lower boundary varied with the strength and diurnal cycle of convective mixing in the planetary boundary layer (PBL). For quiescent meteorological conditions the transition from the PBL to the background layer was usually very sharp, with backscatter decreases sometimes as large as three decades in approximately 70 m. Sharp gradients were also found at the boundaries of shallow (tens of meters) subvisible cirrus clouds. For less stable conditions, associated with vertical aerosol transport by deep cumuliform clouds, backscatter tended to decrease exponentially with altitude. 158 WP-015 CHERTOCK, B., R. Frouin, and R.C. Somerville. Global monitoring of net solar irradiance at the ocean surface: climatological variability and the 1982-1983 El Nino. Journal of Climate, 4(6):639-650 (1991). A new method has been used to generate the first accurate, long-term (84-month) climatology of surface solar irradiance over the world oceans. These monthly mean data cover the period November 1978 through October 1985 on a global, 9° latitude-longitude spatial grid. As an example of the power and usefulness of this technique, the large-scale variability of surface solar irradiance is assessed over the world oceans for the entire (84-month) record. The results demonstrate the sensitivity of the model to large-scale seasonal and interannual phenomena. The reduction in surface solar irradiance due to clouds is evaluated globally both on monthly and long-term climatological scales. Monthly cloud forcing anomalies are found to display eastward propagation over the course of the 1982-1983 El Nino event. The mean January climatology is found to be consistent with the climatology obtained from a general circulation model run in perpetual January mode. This study marks the first large-scale, observation-based examination of cloud solar forcing at the ocean surface. In addition, empirical orthogonal function (EOF) analysis is employed to investigate modes of seasonal and nonseasonal variability. Nonseasonal EOF modes of surface solar irradiance are related to nonseasonal EOF modes of outgoing longwave radiation (OLR). The dominant modes during the 1982-1983 El Nino are associated with eastward propagation in both the shortwave and longwave fields. The association of these modes with El Nino is quantified using the correlation of the mode amplitudes with the Southern Oscillation Index. Finally, a study of the regionally averaged behavior of surface solar irradiance and sea surface temperature (SST) in a section of the tropical Pacific (9°N-9°S, 117°-144°W) during this same period indicates that fluctuations of surface solar irradiance in the tropical Pacific are sometimes a regional response to underlying changes in SST (and associated changes in cloudiness), rather than a driving mechanism responsible for variations in SST. WP-016 Cheung, TJC., and C.G. Little. Meteorological tower, microbarograph array, and sodar observations of solitary-like waves in the nocturnal boundary layer. Journal of the Atmospheric Sciences, 47(2 1):25 16-2536 (1990). Five short-duration disturbances of the stable nocturnal boundary layer, ranging in depth from about 15 m to over 500 m, were observed using a 300-m meteorological tower, 2 sodars, and a 4-station microbarograph array. Four of the events showed characteristic pulse-like sodar signatures; the fifth occurred within the minimum range of the sodars. We show that the events have the characteristics expected of strongly nonlinear deep-fluid internal solitary waves that are transporting and recirculating cold air at a supercritical velocity. The unique sodar signatures, tracing out the form of the waves, are attributed to small-scale turbulent temperature inhomogeneities marking the boundary of the recirculating air as it is transported through the ambient nocturnal boundary layer by the wave. All the events are shown to deviate from the Benjamin-Davis-Ono (BDO) theory, because their amplitude/wavelength and amplitude/stable layer thickness ratios are considerably larger than normally thought appropriate for the weakly nonlinear BDO theory. These events exhibit characteristics that are consistent with those predicted by the nonlinear theory of Tung et al. WP-017 Cheung, TJC., C.G. Little, and H.E. Ramm. Thin acoustic scattering layers observed in the low marine boundary layer. Journal of the Atmospheric Sciences, 47(21):2537-2545 (1990). A novel high-resolution, low minimum-range monostatic sodar, steerable in elevation angle, was tested aboard the research vessel Point Sur during Project FIRE (First Internationa] Satellite Cloud Climatology Project Regional Experiment), 7-16 July 1987. Unusual sodar echoes were observed in the low marine boundary layer for two hours on 13 July 1987; they took the form of thin, intense echo layers that appeared abruptly at the minimum range of the sodar and increased steadily in range to as much as 150 m, before descending equally rapidly back into the minimum range. In each case, if this primary echo reached more than 20-30 m range (dependent upon the antenna elevation angle) it was followed by a second similar echo, which maintained a constant separation in range below the primary echo, before both dropped back in turn beneath the minimum range of the sodar. Such echo patterns have not been reported over the open ocean before, but similar structures have been seen over land and also over an ice shelf. Recent work (Cheung and Little, 1990) has indicated that similar sodar patterns were associated with the passage of internal solitary waves with amplitudes comparable to, or even larger than, the depth of the associated stable layer. Such waves transport recirculating fluid; the sodar echoes are attributed to Bragg scatter from A../2-scale turbulent eddies produced at the interface between the ambient air and the (traveling) recirculating air. The sharp gradients in temperature, humidity, and velocity implicit in these observations would be likely to have significant effect on quasi-horizontal radio wave propagation and also on the flight of aircraft or helicopters operating at low levels over the ocean. WP-018 CHURNSIDE, J.H. Aperture-averaging factor for optical propagation through the turbulent atmosphere. NOAA TM ERL WPL-188 (PB 129338), 48 pp. (1990). We have developed approximate expressions for the aperture-averaging factor of optical scintillation in the turbulent atmosphere. For large apertures and weak path-integrated turbulence with small inner scale, the variance of signal fluctuations is proportional to the -7/3 power of the ratio of the aperture diameter to the Fresnel zone size. If the inner scale is large, the variance is proportional to the -7/3 power 159 of the ratio of the aperture diameter to the inner scale. In strong, path-integrated turbulence, two scales develop. That portion of the variance associated with the smaller scale is proportional to the -2 power of the ratio of the aperture diameter to the phase coherence length. That portion of the variance associated with the larger scale is proportional to the -7/3 power of the ratio of the aperture diameter to the scattering disk. These simple approximations are within a factor of 2 of the measurements. The probability density function is nearly log normal under most conditions. WP-019 CHURNSIDE J.H. Aperture averaging of optical scintillations in the turbulent atmosphere. Applied Optics, 30(1 5): 1982- 1994 (1991). We have developed approximate expressions for the aperture-averaging factor of optical scintillation in the turbulent atmosphere. For large apertures and weak path-integrated turbulence with small inner scale, the variance of signal fluctuations is proportional to the -7/3 power of the ratio of the aperture diameter to the Fresnel zone size. If the inner scale is large, the variance is proportional to the -7/3 power of the ratio of the aperture diameter to the inner scale. In strong, path-integrated turbulence, two scales develop. That portion of the variance associated with the smaller scale is proportional to the -2 power of the ratio of the aperture diameter to the phase coherence length. That portion of the variance associated with the larger scale is proportional to the -7/3 power of the ratio of the aperture diameter to the scattering disk. These simple approximations are within a factor of 2 of the measurements. WP-020 CHURNSIDE, J.H., and R.H. Harrison. Numerical simulation of methane flux measurements using lidar. NOAA TM ERL WPL-204, 28 pp. (1991). We propose a lidar system for remotely measuring methane flux in the atmospheric boundary layer. The concentration is measured using differential absorption lidar, the vertical velocity is measured using aerosol-correlation lidar, and the eddy-correlation technique is used to obtain flux estimates. Numerical simulations using a Monte Carlo approach show measurement uncertainties of about 50% in the methane flux for reasonable system parameters. WP-021 CHURNSIDE, J.H., and RJ. HILL. Irradiance distributions on the human retina from a laser observed through the turbulent atmosphere. NOAA TM ERL WPL-196 (PB196907), 75 pp. (1991). The statistics of position and size of the focal spot on a simulated human retina for laser illumination through refractive turbulence in the atmosphere were measured. Both 3-mm and 7-mm apertures were used under a variety of propagation conditions. No significant mitigating effects of spot broadening or motion were observed. WP-022 CHURNSIDE J.H„ and PA. McGillivary. Measured optical properties of several Pacific fishes. NOAA TM ERL WPL-193 (PB179226), 13 pp. (1991). Reflectivity and depolarization of six species of fishes were measured using blue and green light In general, the fish were between 15% and 25% reflective; values were higher in the blue than in the green. Depolarization varies significantly from species to species and may be useful in remote species identification. WP-023 CHURNSIDE J.H., and PA. McGillivary. Optical properties of several Pacific fishes. Applied Optics, 30(21):2925-2927 (1991). Reflectivity and depolarization of six species of fishes were measured using blue and green light In general, the fish were between 15% and 25% reflective. WP-024 Consortini, A., F. Cochetti, J.H. CHURNSIDE, and RJ. HELL. Laser scintillation, C.2, and /„ measurements in evolving atmospheric turbulence. ICO Topical Meeting on Atmospheric, Volume and Surface Scattering and Propagation, Florence, Italy, August 27-30, 1991. University of Florence, Florence, Italy, 299-302 (1991). Results of simultaneous measurements of laser scintillation, structure constant and inner scale made during continuously evolving atmospheric turbulence comprising low, moderate, and high levels are presented. 160 WP-025 Dabberdt, Wf, HI.. Cole, PM. Hildebrand, T. Horst, YJL Kuo, C. Martin, K.S. GAGE, W.L. ECKLUND, R.G. STRAUCH, E.R. WESTWATtK, and W.L. Smith. The integrated sounding system — a new observing system for mesoscale research. Preprints, 7th Symposium on Meteorological Observations and Instrumentation, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, MA, J128-J133 (1991). No abstract. WP-026 Dabberdt, Wf, C. Martin, H.L, Cole, P.H. Hildebrand, T. Horst, Y.H. Kuo, K.S. GAGE, W.L. ECKLUND, R.G. STRAUCH, E.R. WESTWATER, H.E. Revercomb, and Wl. Smith. An integrated data assimilation and sounding system. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, MA, 276-279 (1991). No abstract. WP-027 Decker, M.T., and JA. SCHROEDER. Calibration of ground-based microwave radiometers for atmospheric remote sensing. NOAA TM ERLWPL-197(PB183111), 16 pp. (1991). Two procedures used routinely at the NOAA Wave Propagation Laboratory to calibrate ground-based microwave radiometers are described. One technique uses collocated radiosonde data with an atmospheric absorption model to calculate the absolute value of atmospheric radiation that should be observed. The other technique uses the known dependence of radiation on elevation angle to calibrate the radiometer directly, without radiosonde information. The radiometer equation that is used to convert instrumental voltages and temperatures to a measurement of downwelling atmospheric radiation is derived and its implementation is discussed. WP-028 DERR, VJL, R.S. Stone, L.S. FEDOR, and H.P. Hanson. A parameterization for the shortwave transmissivity of stratiform water clouds based on empirical data and radiative transfer theory. Journal of the Atmospheric Sciences, 47(23):2774-2783 (1990). Surface measurements of solar flux and total integrated liquid-water content, radiosonde data, and infrared satellite images are analyzed in conjunction with radiative transfer calculations to derive an empirical parameterization for the shortwave transmissivity of continental stratiform water clouds. The data were collected near Denver, Colorado, over a period of six years. Seventeen days on which uniform stratiform clouds persisted over the observing site were selected for detailed analysis, and form the basis for deriving the parameterization. A multiple reflection radiative transfer model is employed to estimate stratus cloud transmissivity in terms of the measurable liquid-water path (LWP). A nonlinear fit of estimated transmissivities to the corresponding observations of LWP yields close agreement with a previous, more complicated parameterization. The derived expression for cloud transmissivity is used to predict mean daily surface fluxes for 61 days during which periods of stratiform clouds were observed over the Denver area. A comparison between predicted and measured fluxes shows agreement to within ±4%, with best agreement for clouds of moderate optical thickness. Potential sources of error are identified with sensitivity studies. WP-029 DONALL, E.G., MA. SHAPIRO, and PJ. NEIMAN. Frontogenesis in a rapidly intensifying extratropical marine cyclone. Preprints, 1st International Winter Storms Symposium, New Orleans, LA January 13-18, 1991. American Meteorological Society, Boston, MA 393-397(1991). No abstract. WP-030 DOUGLAS, M.W. The selection and use of dropwindsonde-ecjuipped aircraft for operational forecasting applications. Bulletin of the American Meteorological Society, 71(12):1746-1757 (1990). This article discusses the feasibility of using dropwindsonde-equipped aircraft to obtain meteorological observations over oceanic data- void areas for operational forecasting applications. Such in-situ meteorological observations would provide measurements of wind, temperature, and moisture at a higher vertical resolution and greater accuracy than currently available from satellite-derived observations. Such airborne observations, if globally obtained, would greatly enhance global datasets for both numerical weather prediction and for research studies of large-scale phenomena, such as the El Nino/Southern Oscillation. The aircraft could also serve as platforms for collecting frequent oceanic thermal and current information. The advantages and limitations of a dropwindsonde-based observing system are compared with current and proposed ground- and satellite-based systems. 161 WP-031 DOUGLAS, M.W., L.S. FEDOR, and MA. SHAPIRO. Polar low structure over the northern Gulf of Alaska based on research aircraft observations. Monthly Weather Review. 1 19(l):32-54 (1991). During the 1987 Alaska Storms Program, a polar low that developed over the northern Gulf of Alaska was investigated during two flights by a WP-3D research aircraft on successive days. Analyses based on data obtained from omega dropwindsondes during the first flight showed the small (-300 km) horizontal scale of the vortex. The vortex center was characterized by suppressed cloudiness on both days and was decidedly warmer at low levels than its surroundings. The vorticity associated with the polar low was largest near the surface and decreased rapidly with height on the first day, with only a very weak circulation evident by 700 mb. Coldest 500 mb temperatures and lowest static stabilities were found directly above the surface low. On the second day the vortex was more intense at midtropospheric levels than on the previous day, and convective clouds extended to higher levels. WP-032 DOUGLAS, M.W., MA. SHAPIRO, and L.S. FEDOR. The structure of a cold frontal zone in a rapidly deepening cyclone over the North Pacific Ocean. Proceedings, 1st International Winter Storm Symposium, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, MA, 387-392 (1991). No abstract. WP-033 EBERHARD, Wl. Cloud measurements by coherent lidar: some examples and possibilities. Technical Digest, series vol. 12, Coherent Laser Radar: Topical Meeting on Technology and Applications, Snowmass, CO, July 8-12, 1991. Optical Society of America, Washington, DC, 174-176 (1991). No abstract. WP-034 EBERHARD, WJL., R.E. CUPP, K.R. Healy, J.M. Intrieri, and R.J. Willis. Sensing of cloud properties with infrared lidar. Preprints, 7th Symposium on Meteorological Observations and Instrumentation (Special Session on Laser Atmospheric Studies), New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, MA 452-457 (1991). No abstract. WP-035 EBERHARD, WL, and MJ. POST. C02 lidar techniques for observing characteristic particle size of selected cloud types. Extended Abstracts, Symposium on Lower Troposphcric Profiling: Needs and Technologies, Boulder, CO, September 10-13, 1991. American Meteorological Society, Boston, MA, 7-8 (1991). No abstract. WP-036 Edson, J.B., C.W. FAIRALL, P.G. Mestayer, and S.E. Larsen. An experimental and theoretical investigation of the inertial-dissipation method for computing air-sea fluxes. NOAA TM ERL WPL-199, 80 pp. (1991). The inertial-dissipation method has long been used to estimate air-sea fluxes from ships because it is not necessary to correct for ship motion. A detailed comparison of the inertial-dissipation fluxes with the eddy covariance method is given using data from the HEXOS main experiment, HEXMAX. In this experiment, inertial-dissipation packages were deployed at the end of a 17-m boom, in a region relatively free of flow distortion, and on a mast 7 m above the platform (26 m above the sea surface) in a region of considerable flow distortion. The effects of flow distortion and an extensive error analysis of both inertial-dissipation and covariance measurements is given. We show that the inertial-dissipation measurements are much less affected by the flow distortion caused by the platform as well as by the boom itself. The inertial-dissipation (boom and mast) and boom covariance estimates of stress agree within ±20%. The latent heat flux estimates agree within approximately ±45%. The sensible heat flux estimates agree within ±26% after correction for velocity contamination. The larger uncertainty in the latent heat fluxes is due to poor performance of our Lyman-a hygrometers in the seaspray environment Total production of turbulent kinetic energy approximately equals dissipation, with an imbalance of approximately 12% based on our value of the effective Kolmogorov constant. Improved parameterizatiora for the stability dependence of the dimensionless humidity and temperature structure functions are given. Using these functions and a von Karman constant of 0.4, we find a best fit for effective Kolmogorov constants of 0.55 for velocity and 0.79 for temperature and humidity. 162 WP-037 Edson, J.B., C.W. FAIRALL, P.G. Mestayer, and SJE. Larsen. A study of the inertial-dissipation method for computing air-sea fluxes. Journal of Geophysical Research, 96:10,689-10,711 (1991). The inertial-dissipation method has long been used to estimate air-sea fluxes from ships because it is not necessary to correct for ship motion. A detailed comparison of the inertial-dissipation fluxes with the direct covariance method is given, using data from the Humidity Exchange Over the Sea (HEXOS) main experiment, HEXMAX. In this experiment, inertial-dissipation packages were deployed at the end of a 17-m boom, in a region relatively free of flow distortion, and on a mast 7 m above the platform (26 m above the sea surface) in a region of considerable flow distortion. An error analysis of the inertial-dissipation method indicates that stress is most accurately measured in near- neutral conditions whereas scalar fluxes are most accurately measured in near-neutral and unstable conditions. It is also shown that the inertial-dissipation stress estimates are much less affected by the flow distortion caused by the platform as well as by the boom itself. The inertial-dissipation (boom and mast) and boom covariance estimates of stress agree within ±20%. The latent heat flux estimates agree within approximately ±45%. The sensible heat flux estimates agree within ±26% after correction for velocity contamination of the sonic temperature spectra. The larger uncertainty in the latent heat fluxes is due to poor performance of our Lyman-Ot hygrometers in the sea-spray environment. Improved parameterizations for the stability dependence of the dimensionless humidity and temperature structure functions are given. These functions are used to find a best fit for effective Kolmogorov constants of 0.55 for velocity (assuming a balance of production and dissipation of turbulent kinetic energy) and 0.79 for temperature and humidity. A Kolmogorov constant of 0.51 implies a produc- tion/dissipation imbalance of approximately 12% in unstable conditions. WP-038 FAIRALL, C.W. The humidity and temperature sensitivity of clear-air radars in the convective boundary layer. Journal of Applied Meteorology, 30(8): 1064- 1074 (1991). A top-down/bottom-up diffusion model is used to evaluate the relative contributions of humidity, temperature, and their cross-correlation into the radar refractive index structure function parameters, C02, in the convective planetary boundary layer (PBL). Profiles of C„2 can be measured continuously with so-called clear-air Doppler wind profilers. Extraction of information about PBL dynamical parameters is more straightforward if C,2 is dominated by either moisture (C,,2) or temperature (Cy2). In the lower part of the PBL the surface Bowen ratio, B„, determines this dominance; in the upper part of the PBL the inversion Bowen ratio, Bjt is the primary determining factor. The model suggests that humidity accounts for at least 75% of C.2 over tropical and mid-latitude oceans. Polar oceans, where B0 often exceeds 0.5, may not be dominated by temperature or moisture. Over land, B0 can easily vary from 0.1 to 10. Geographical regions with B0 > 5 will be dominated by Cj2. Even for large values of B„, the upper part of the PBL will often be dominated by humidity. WP-039 FAIRALL, C.W., and J.B. Edson. Modeling the droplet contribution to the sea-to-air moisture flux. In Bubble-Mediated Sea-Air Exchange, E.C. Monahan and M.A. Van Patten (eds.), CT Sea Grant College Program, University of Connecticut, Groton, CT, 121-146 (1990). Assessing the importance of sea spray for air-sea moisture transfer is a formidable observational and modeling problem. From a modeling perspective, the primary roadblock is the wide range of size scales (from droplet microphysical to atmospheric boundary layer) that must be considered. Both ensemble average budget equation and Monte Carlo simulation approaches are being pursued. It is now clear that the total droplet evaporation is dominated by rather large droplets (on the order of 50 urn radius), which are so massive that their turbulent transport is affected by inertia. This further complicates the modeling task. Application of ensemble average and Monte Carlo models to this problem is still in its infancy. To date, only somewhat idealized cases (fresh water, ad hoc concentration profiles, laboratory situations, etc.) have been examined. The oceanic droplet source strength as a function of wind speed also represents an important uncertainty. The current state of knowledge suggests that droplets significantly enhance the moisture transfer efficiency at wind speeds in excess of 15 m s . WP-040 FAIRALL, C.W., and A.S. FRISCH. Diurnal and annual variations in mean profiles of C„2. NOAA TM ERL WPL-195 (PB 181719), 36 pp. (1991). Individual profiles of turbulent refractive index structure function parameter, C„2, exhibit considerable vertical structure and temporal variability. The planetary boundary layer (PBL) is characterized by significant diurnal variations over land because of the daily solar heating cycle. Above the PBL, the turbulence is primarily due to instabilities associated with breaking gravity waves and local fluctuations due to a broad spectrum of gravity waves. We have constructed a typical average C„2 profile for optical wavelengths that takes these physical differences into account by considering the PBL and free atmosphere separately. Physical models of turbulence in these two regimes are used as a basis for constructing the climatology. The PBL profiles are obtained from a boundary layer turbulence model driven by climatological values of surface forcing (winds and net radiation), boundary layer depth, and internal energy partitioning (Bowen ratio and soil flux). The free atmospheric profile is obtained using a gravity-wave-induced turbulence model, which implies that the temperature 163 structure function parameter, Cj- , is constant with altitude within an atmospheric height regime (either the troposphere or the stratosphere). The values chosen are a compromise between the model predictions (based on an estimate of the global gravity wave energy) and 5 years of measurements of radar C, obtained by NOAA radar wind profilers in Colorado. In the free atmosphere, variations in C„2 are log normally distributed (although it may be bimodal) at a selected height Roughly 68% of high resolution measurements fall within a factor of 10 of the median (or log-average). Linear averages are a factor of 6 greater than log averages in the troposphere and a factor of 40 greater in the stratosphere. WP-041 FAJRALL, C.W., A.B. White, and D.W. Thomson. A stochastic model of gravity-wave-induced clear-air turbulence. Journal of the Atmospheric Sciences, 48(15): 1771-1790 (1991). We examine the consequences of using a vertical wavenumber spectral model to describe variations of vertical profiles of atmospheric variables (horizontal and vertical wind, temperature, and other scalars) about a mean profile. At high wavenumbers the model exhibits a wavenumber to the -3 dependence, which is characteristic of a continuum of internal gravity waves whose amplitudes are controlled by a breaking process. By employing a random phase between wavenumber amplitude components, a reverse Fourier transform of the spectrum yields simulated profiles of velocity and thermal variability as well as shear and Brunt- Vaisala frequency variability. Individual components of the vertical shear of the horizontal wind and the Brunt-Vaisala frequency exhibit Gaussian distributions; the square of the magnitude of the shear exhibits a Rice-Nakagami distribution. Assuming regions with Ri < 0.25 are turbulent, we can examine a number of aspects of the occurrence of clear-air turbulent breakdown in the stratified free atmosphere. For a typical tropospheric condition, the average turbulent layer thickness turns out to be about 35 m and about 20% of the troposphere appears to be actively turbulent. The majority of the turbulent layers appear to be due to autoconvective overturning instead of Kelvin-Helmholtz dynamic instability. Computations of profiles of the refractive index structure function parameter C„2 and the rate of dissipation of turbulent kinetic energy, e, are found to be quite sensitive to the assumptions of the relationship of turbulent length scale to layer thickness, the growth of turbulent layers after breakdown, and the threshold sensitivity and sampling strategy of measurement systems (e.g., clear-air radar). WP-042 FAJRALL, C.W., and G.S. Young. A field evaluation of shipboard performance of an infrared hygrometer. Proceedings, 7th Sympo- sium on Meteorological Observations and Instrumentation (Special Sessions on Laser Atmospheric Studies), New Orleans, LA, January 14-17, 1991. American Meteorological Society, Boston, MA, 311-315 (1991). No abstract. WP-043 Fionda, E., MJ. FALLS, and E.R. WESTWATER. Attenuation statistics at 20.6, 31.65, and 52.85 GHz derived from emission measure- ments by ground-based microwave radiometers. IEE Proceedings (Institution of Electrical Engineers), 138(l):46-50 (1991). Two seasons (December 1987 to February 1988 and July 1988 to September 1988) of thermal emission measurements, taken by a multi- channel ground-based microwave radiometer, are used to derive single-station zenith attenuation statistics at 20.6 and 31.65 GHz. For the summer period, statistics are also derived at 52.85 GHz. In addition, data from two radiometers located 50 km apart are used to derive two- station attenuation diversity statistics at 20.6 and 31.65 GHz. The multi-channel radiometer was operated at Denver, Colorado, USA, and the dual-channel device was operated at Platteville, Colorado. The diversity statistics are presented by cumulative distributions and by bivariate frequency distributions. The frequency distributions are analyzed when either one or both stations have liquid clouds. WP-044 FRISCH, A.S. On the measurement of second moments of turbulent wind velocity with a single Doppler radar over non-homogeneous terrain. Boundary-Layer Meteorology, 54:29-39 (1991). The measurement of turbulent wind quantities with a single Doppler radar requires a horizontal homogeneity assumption. When the terrain is not horizontally homogeneous, then the measurement of the various moments is contaminated by the gradients of these moments. However, by scanning the radar at three different elevation angles, the contamination from these gradients can be removed from the second moment quantities of interest WP-045 FRITZ, R.B., and J.E. GAYNOR. Boundary layer atmospheric conditions during air pollution events in Boulder, Colorado. Preprints, 7th Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, MA, 290-293 (1991). No abstract. 164 WP-046 Gal-Chen, T., M. Xu, and WL. EBERHARD. Momentum and heat flux estimation in the planetary boundary layer (PBL) with a 10.6 urn Doppler lidar. Proceedings, 7th Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, MA, J245-J248 (1991). No abstract. WP-047 GAYNOR, J.E., C.B. Baker, and B. Templeman. Fine time-scale comparisons between Doppler sodar and sonic anemometer-derived winds. Proceedings, 7th Conference on Meteorological Observations and Instrumentation, New Orleans, LA, January 13-17, 1991. American Meteorological Society, Boston, MA, 401-404 (1991). No abstract. WP-048 GAYNOR, ]£.-, and R.M. BANTA. Relation between cross-canyon circulations and vertical mixing into the Grand Canyon. Preprints, 7th Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, MA, 384-387 (1991). No abstract. WP-049 GAYNOR, J.E., R.B. FRITZ, S. Summers, DJB. WOLFE, H. Sievering, G. Kenniston, and G.M. Mathews, Jr. Results of the Boulder Air Quality Study - Winter of 1988-1989. NOAA TM ERL WPL-194 (PB191858), 85 pp. (1991). The intent of the Boulder Air Quality Study (BAQS) was to determine the influence of meteorology on pollution episodes in the Boulder Valley, the sources of visible pollution, and the relative importance of transports into and out of the Boulder Valley to local episodes. A cooperative effort of virtually all levels of government, the results of BAQS may be applicable to many urban centers located immediately downwind of large mountain ranges. WP-050 GAYNOR, ]£.., D.E. WOLFE, and Y. Mori. The effects of horizontal pressure gradients and terrain in the transport of pollution in the Grand Canyon region. Preprints, 84th Annual Meeting and Exhibition - AWMA, Vancouver, British Columbia, Canada, June 16-21, 1991. Air and Waste Management Association, Pittsburgh, PA, 47.1, 15 pp. (1991). No abstract. WP-051 GEORGES, T.M., and G.D. Thome. An opportunity for long-distance oceanographic and meteorological monitoring using over-the-horizon defense radars. Bulletin of the American Meteorological Society, 71(12): 1739-1745 (1990). Ocean-monitoring tasks can be added to military over-the-horizon radars at modest incremental cost A surface-wind-direction analysis for the Caribbean made with a U.S. Navy radar illustrates one capability of such systems. Surface wind speed and ocean wave height are also available as by-products of the radars' surveillance missions, if longer coherent-integration times are used to resolve the second-order sea echo. WP-052 Gerace, G.C., EJC. Smith, and E.R. WESTWATER. A comparison of cloud attenuation models using measured cloud data. Proceedings, 15th NASA Propagation Experimenters Meeting (NAPEX XV), London, Ontario, Canada, June 28-29, 1991. Jet Propulsion Labor- atory/NASA, Pasadena, CA/Washington, DC, 95-106 (1991). Simultaneous measurements of surface atmospheric parameters and cloud liquid water are used to test and compare the accuracy of three different cloud models. 165 WP-053 Gossard, E.E., S.Y. Matrosov, and R.G. STRAUCH. Clear-air wind profilers as potential hydrometeor identifiers. Proceedings, Symposium on Lower Tropospheric Profiling: Needs and Technologies, Boulder, CO, September 10-13, 1991. American Meteorological Society, Boston, MA, 67-70 (1991). No abstract. WP-054 Gossard, E.E., S.Y. Matrosov, R.G. STRAUCH, and D.C. WELSH. Clear-air wind profilers as cloud monitors and hydrometeor identifiers. Proceedings, AGARD Fall 1991 Electromagnetic Wave Propagation Panel Symposium on Remote Sensing of the Propagation Environment, Cesme, Turkey, September 30 - October 4, 1991. AGARD (Advisory Group for Aerospace Research and Development), Neuilly-Sur-Seine, Franc*, 31.1-31.9 (1991). Clear-air sensing radars, which are used for wind sounding from surface platforms, are now widely deployed. They are usually designed to measure the Doppler-sensed movement of clear-air refractive index inhomogeneities, but they also provide an excellent tool for sensing ice and water particles in clouds. These radars usually have a very low detection threshold and long averaging time so that size distributions of particles as small as 100 um diameter with mean vertical fall velocities (Vf) as small as 0.2 m s'1 can be accurately measured. We present data from two events in which clouds form, intensify, and finally produce precipitation. Height profiles are displayed and analyzed as ZRFf plots vs. height, where Z is the radar reflectivity factor, R is liquid flux (rain), and Vf is the mean fall velocity in quiet air derived from the radar-measured vertical velocity. It is shown how these radars can provide 1) cloud layer structure above lower overcast, 2) height profiles of liquid mean dropsize, 3) the ice-water transition level compared with the 0° isotherm, 4) height profiles of rain rate, and 5) inferences about the identity of hydrometeors vs. height. WP-055 Gossard, E.E., RG. STRAUCH and RJL Rogers. Evolution of dropsize distributions in liquid precipitation observed by ground-based Doppler radar. Journal of Atmospheric and Oceanic Technology, 7(6):8 15-828 (1990). A technique is described for using ground-based Doppler radars to monitor the development of the drop-size spectra of number density, liquid-water density, and liquid flux, in time and height. It is shown how such observations reveal the height-time location of rapid growth zones and how drop-size growth rates can be remotely sensed in an important subrange of the number-density spectrum. A model that balances convergence of accretional growth in the size domain with convergence of vertical flux of drop number in the height domain reproduces major features of the observations. These include change in number density with height, shifts toward larger sizes with decreas- ing altitude in the cloud, and multiple peaks in the drop-size spectrum of precipitation particles. WP-056 Gozani, J. Two-scale expansion of wave propagation in a random medium. Computer Physics Communications, 65(1 -3): 117-120 (1991). This paper presents an innovative technique for performing partial inversion of the operator of a wide class of transport-like equations encountered in mathematical physics. This inversion is an alternative to the traditional selective summation technique of the iterated series solution to a corresponding Volterra integral equation. Comparing with the regular iterated series for which the zero order iterate is the worst approximation, it was computationally found that our zero-order term has an exact high frequency and acceptable low frequency content. It is suggested that the first iteration that reflects a single scattering event will compensate for the inaccuracy in the low frequency region. Thus two terms in the series will be a sufficient approximation for practical purposes, eliminating the need for high iterations. WP-057 Gozani, J. Wave propagation in an intermittent turbulent medium. Proceedings, ICO Topical Meeting on Atmospheric, Volume and Surface Scattering and Propagation, Florence, Italy, August 27-30, 1991. University of Florence, Florence, Italy, 23-26 (1991). No abstract. WP-058 HARDESTY, R.M., W.L. EBERHARD, and R.M. BANTA. Doppler lidar measurements of boundary layer vertical motion and horizontal structure. Preprints, 7th Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA January 14-18, 1991. American Meteorological Society, Boston, MA, J249-J252 (1991). No abstract. 166 WP-059 HARDESTY, R.M., and B.J. Rye. Simulations of discrete spectral peak estimators for single and multiple lidar pulse returns. Technical Digest, series vol. 12, Coherent Laser Radar: Technology and Applications Topical Meeting, Snowmass, CO, July 8-12, 1991. Optical Society of America, Washington, DC, 219-222 (1991). No abstract. WP-060 Harlan, J.A., T.M. GEORGES, and R.M. JONES. PROFILE— a program to generate profiles from HARPO/HARPA environmental models. NOAATMERLWPL-198, 46 pp. (1991). We describe a FORTRAN computer program, PROFILE, that will generate plotting-command files for profile plots of the environmental models (e.g., sound speed, current or wind velocity, temperature) used with the acoustic ray tracing programs HARPO (underwater acoustics) and HARPA (atmospheric acoustics). Profiles (plots of depth/height versus environmental model parameter) can be made for any longitude-latitude for models that depend on all three spatial dimensions. A companion report describes an associated plotting program that produces PostScript files as well as screen graphics for PC-compatible computers. An additional companion report describes a computer program that calculates contours of these environmental model parameters. Includes a floppy disk with computer programs and a sample case. Also included are instructions for obtaining the programs (with updates) via Internet WP-061 Harlan, J.A., R.M. JONES, and T.M. GEORGES. PSGRAPH— A plotting program for PC-HARPO, PROFILE, CONPLT, and EIGEN. NOAA TM ERL WPL-203, 65 pp. (1991). We describe a FORTRAN computer program, PSGRAPH, that generates PostScript graphics files and PC-compatible screen graphics. Input for the program is provided by files produced by the PROFILE (Harlan et al., 1991a), CONPLT (Harlan et al.. 1991b), and EIGEN programs (Weickmann et al., 1989), and the PC-version of the HARPO program (Georges et al., 1990). The program provides for user- selectable PostScript plotting parameters including text font size, magnification factor, and line width of the plots. In addition, a data editing factor allows the user to reduce the size of the output PostScript file while retaining the resolution of the plot Includes a floppy disk with computer programs and sample cases. Also includes instructions for retrieving PSGRAPH via Internet WP-062 HILL, RJ. Comparison of experiment with a new theory of the turbulence temperature structure function. Physics of Fluids A, 3(6): 1572-1576 (1991). The theory for the structure function of an advected scalar quantity in turbulent flow by Eff inger and Grossmann [Physics of Fluids A, 1, 1021 (1989)], is compared with data. The theoretical structure function is transformed to a spatial power spectrum, which is found to have negative values. The theory does not agree with data for the spectrum. The theory has startling differences with Batchelor's theory [Journal of Fluid Mechanics 5, 113 (1959)] for the viscous-diffusive and viscous-convective ranges. WP-063 HILL, RJ. Inner scale, C02, and surface fluxes obtained in the atmospheric surface layer using scintillation. Proceedings, ICO Topical Meeting on Atmospheric, Volume and Surface Scattering and Propagation, Florence, Italy, August 27-30, 1991. University of Florence, Florence, Italy, 307-310 (1991). No abstract. WP-064 HILL, RJ., GJA. Ochs, J.J. WILSON, DA. Furtney, and J.T. Priestley. Results of the 1988 fluxes-from-scintillation experiment NOAA TM ERL WPL-192 (PB 178392), 147 pp. (1991). An experiment was performed to assess three new concepts for the remote sensing of heat and momentum fluxes in the atmospheric surface layer. These concepts use optical scintillation caused by turbulence along a horizontal propagation path from a transmitter to a receiver. The fluxes are derived from the measured scintillation using Monin-Obukhov similarity theory (MOST) of the horizontally homogeneous atmospheric surface layer. The first concept is to measure refractive-index structure parameters, Cn\ and inner scale, L, using an optical innerscale meter; the values of C„2 and lQ are empirically related to the heat and momentum fluxes using MOST. The second concept is to use scintillometers to measure Co2 at two heights; the ratio of the two C„2-values gives surface-layer stability; C.2 and stability then give heat and momentum flux using MOST. The third concept is to measure apparent mean vertical wind by deploying an 167 optical-scintillation cross-wind sensor with its measurement axis turned vertically. If this apparent vertical wind has Monin-Obukhov similar- ity scaling, then its measurement can be used to determine heat flux. The successfulness of these methods is in the order in which they were described above. In particular, the first method, that of measuring lQ and C„2, appears to be very robust in that it produces good results even for very non-ideal conditions. We expect that it will be used for future experiments on a routine basis. WP-065 Intrieri, J.M., W.L. EBERHARD, and T. UTTAL. Determination of cirrus cloud particle effective radii using radar and lidar backscattering data. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, MA, 809-812 (1991). No abstract. WP-066 Intrieri, J.M., T. UTTAL, R.M. HARDESTY, W.L. EBERHARD, and R.E. CUPP. Comparison of measurements made with NOAA's C02 Doppler lidar and 3.2 cm Doppler radar. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, MA, 867-870 (1991). No abstract. WP-067 JONES, R.M., and T.M. GEORGES. HARPX— -a program to extend HARPO or HARPA ray paths in horizontally uniform media. NOAA TM ERL WPL-201, 43 pp. (1991). We describe a FORTRAN computer program HARPX that can extend ray paths in horizontally uniform media if the ray paths have been calculated by the ray tracing programs HARPO or HARPA. The HARPX program extends HARPO or HARPA ray path calculations that have been made for two or three ray loops (hops) in a horizontally uniform medium to more loops and correspondingly longer ranges. The input is a HARPO or HARPA rayset file, and the output is another rayset file. The HARPX program extends the calculations in range by adding complete ray cycles to both odd and even ray loops. A floppy disk containing the program and sample input data is included. WP-068 JORDAN, J.R., and M.T. Decker. Calibration transfer target for a microwave radiometric profiling system. NOAA TM ERL WPL-189 (PB 129080), 14 pp. (1990). The Wave Propagation Laboratory has been operating a six-channel radiometric profiler since 1981 at Stapleton International Airport in Denver, Colorado, to retrieve temperature profiles. The atmospheric absorption at these frequencies is too large for tipping calibrations to be used. Therefore, data from collocated National Weather Service radiosondes have been used to calibrate the radiometric profiler. This technique provides the necessary profiler calibration but limits its use to locations with regular radiosonde launches. Therefore, a prototype calibration transfer target was constructed at Stapleton Airport to demonstrate the feasibility of using the target to help maintain a network of radiometric profilers not located at radiosonde sites. The calibration target is described, along with potential error sources. A second, 53.85 GHz, radiometric profiler is calibrated with the target and shows a 0.65 K bias. Finally, an error analysis of the target's accuracy for absolute calibration is presented and found to be 1.33 K. WP-069 KATMAL, J.C., and J.E. GAYNOR Another look at sonic thermometry. Boundary-Layer Meteorology, 56:40 1-4 10 (1991). In this note we reassess the role of sonic thermometry in boundary-layer studies. The sonic temperature signal, when corrected for crosswind velocity contamination, very closely approximates the virtual temperature of air. This variable is needed for many boundary-layer calculations. We describe preliminary tests with a new sonic anemometer-thermometer that performs the velocity correction in real time. Our test results offer new insights into the nature of the velocity error on temperature standard deviations and fluxes. They also draw attention to the high noise threshold that appears as an/*' rise in the/5(/) spectrum when spectral levels drop below 10"4 "C2. WP-070 KING, C.W. Forecasting carbon monoxide levels in downtown Denver using statistical models. Master's Thesis, University of Colorado, Boulder, CO, 125 pp. (1990). This thesis presents a study of the atmospheric parameters which determine the concentration of carbon monoxide (CO) during the winteT months in Denver, Colorado. Through the use of multiple regression techniques, both microscale and synoptic-scale parameters are identified 168 which arc most important for determining CO levels in Denver. The thesis then develops statistical models for predicting CO levels in Denver, using the previously measured atmospheric parameters and CO concentrations. These models are designed to give day-to-day forecasts of CO levels for immediate decision-making by air pollution agencies. An examination of the relationship between various microscale parameters and CO concentrations in downtown Denver during the late afternoon (1500-1800 MST) revealed that the resultant wind speed, traffic volume, and stability in the lower atmosphere are the most important variables for determining CO levels. An examination of the relationship between synoptic-scale weather patterns and air quality in Denver showed a strong relationship between the two. In particular, a surface lee trough through eastern Colorado in conjunction with 500-mb ridging over Colorado produced the necessary atmospheric conditions for CO accumulation in downtown Denver. An investigation of the trends in weekday late- afternoon CO levels spanning seven consecutive winters revealed some important results. The CO levels remained relatively unchanged between the winters of 1983/84 through 1986/87 and then decreased dramatically (40%-50%) between the winters of 1986/87 and 1989/90. The decrease resulted from reduced emissions of CO and were not related to changing weather patterns. This thesis developed two types of air quality forecasts: 1) a 24-hr forecast based on synoptic-scale meteorological variables; and 2) a 3-hr forecast based on selected microscale parameters. Because the models were developed for a particular site, their weakness lies in limited transferability to another site or even outside the range of their data. The 24-hr forecast model depended on predicted synoptic variables as input. The difficulty of predicting surface pressure patterns with good accuracy from the 36-hr Numerical Grid Model (NGM) limited the accuracy of the air quality forecast The 3-hr forecast model performed satisfactorily for predicting CO levels during the 1989/90 winter air pollution season. WP-071 KING, C.W. The relationship between synoptic and microscale meteorological parameters during poor air quality events. Preprints, 7th Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, MA, 330-333 (1991). No abstract. WP-072 KING, C.W., and D. Ruffieux. A real-time color display of sodar data for assessing pollution dispersion conditions. Proceedings, 7th Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 13-18, 1991. American Meteo- rological Society, Boston, MA, J195-J198 (1991). No abstract. WP-073 Kovacs, L.M., and JU. CHURNSIDE. Optical remote sensing. NOAA TM ERL WPL-191 (PB 169755), 82 pp. (1991). The random absorption and refraction experienced by the electromagnetic wave produce fluctuations in the wave amplitude and phase as observed at a remote point. The impact of these fluctuations on a double-spatial filtering receiver is evaluated by performing a diffraction analysis on the system. The diffraction analysis covers a complete study of an electromagnetic wave propagating through the atmosphere, and through the double-spatial filtering receiver in order to obtain the wave field at the focal plane. The transmitter can be any natural or artificial source. The choice in this configuration is the sun. Theoretically, this technique provides high spatial resolution measurements of wind velocity and turbulence. WP-074 KROPFLL RA-, W.F. Dabberdt, RJ. Doviak, A.S. FRISCH, T. Gal-Chen, RM. HARDESTY, P.H. Hildebrand, R.M. Rabin, J.M. Schneider, J.M. WILCZAK, and J.J. WILSON. The atmospheric boundary layer: Panel report. In Forty Years of Radar Research in the Atmosphere, Radar in Meteorology: Battan Memorial and 40th Anniversary Radar Meteorology Conference, Chap. 27b. David Atlas (ed.), American Meteorological Society, Boston, MA, 528-533 (1990). No abstract. WP-075 Kuo, YTL, MA. SHAPIRO, and E.G. DONALL. The interaction between baroclinic and diabatic processes in a numerical simulation of a rapidly intensifying extratropical marine cyclone. Monthly Weather Review, 119(2):368-384 (1991). This study addresses the relative contributions of adiabatic baroclinic and diabatic processes and their interaction in the evolution of a rapidly intensifying marine cyclone. Two numerical experiments were performed using a limited-area mesoscale model. The adiabatic simulation showed that the surface cyclone was associated with the quasi-geostrophic vertical motion forcing of a mid-tropospheric shortwave for a period greater than 12 hours, suggesting the presence of deep baroclinic forcing during the evolution of the storm. The full-physics simulation produced major cyclogenesis with a central pressure of 967 mb and a deepening of 37 mb in 24 h. The model simulated the 169 development of comma-shaped cloud patterns, which compared favorably with satellite observations of the storm. Further analysis showed that the rapid cyclogenesis was strongly related to moist frontogenesis at the warm front. During rapid storm intensification, the heavy precipitation, the generation of vorticity, strong surface frontogenesis, and large surface pressure falls all took place in the vicinity of the warm front Quasi-geostropic vertical velocity diagnosis of the full-physics simulation suggested a strong interaction between baroclinic and diabatic processes in the course of rapid development. The latent heat release significantly modified the frontal structure of the storm to reinforce its adiabatic secondary circulation. As a result, the adiabatic component of the vertical motion in the full-physics simulation was three times larger than that in the adiabatic simulation. Moreover, the upward and downward vertical motion induced by latent heat release was in phase with the secondary circulation associated with the adiabatic frontogenesis. The enhanced frontal circulation provided strong low-level moisture convergence to stimulate further frontal precipitation, establishing a positive feedback. Because of the large amount of latent heating associated with the warm frontal precipitation, diabatic heating was the dominant forcing mechanism for the vertical motion of the simulated storm during its rapid intensification. These results clearly indicate that it is not appropriate to treat the contribution of latent heat release (or other physical processes) to rapid development as a linear addition to the adiabatic dynamics, as has been done in most model sensitivity experiments. Rather, extratropical cyclogenesis should be viewed in the context of moist baroclinic instability with nonlinear interactions between the baroclinic dynamics and diabatic processes. WP-076 LATAITIS, R.J. A radar equation for the radio-acoustic sounding of temperature. Extended Abstracts, Symposium on Lower Tropo- spheric Profiling: Needs and Technologies, Boulder, CO, September 10-13, 1991. American Meteorological Society, Boston, MA, 89-90 (1991). No abstract. WP-077 LATAITIS, RJ. The longitudinal-transverse spatial coherence function for a spherical wave propagating through homogeneous atmospheric turbulence: implications for RASS. NOAA TM ERL WPL-206, 19 pp. (1991). The parabolic wave equation and the Bourret approximation are used to derive an expression for the second-order spatial coherence function of a spherical wave propagating through homogeneous atmospheric turbulence. Both the longitudinal and transverse coherence of the wave field are considered. In contrast with existing plane-wave results, the spherical-wave coherence normalized by its value in the absence of inhomogeneities depends not only on the transverse separation of the observation points but also on their mean transverse position. This inhomogeneity of the normalized second-order statistics disappears as the longitudinal separation between the observation planes tends to zero. The normalized coherence for a spherical wave can be expressed as the exponential of a complex factor, as in the plane wave case. The imaginary component of the exponent describes the turbulence induced excess phase-path difference between the two observation planes. The modulus of the normalized coherence can be used to estimate the longitudinal and transverse coherence lengths p, and p„ respectively. The longitudinal spherical-wave coherence length is found to be essentially identical to the plane-wave result For uniform isotropic turbulence described by a van Karman-type refractive index spectrum, it can be approximated by p, = p, pjAp] + P2), where p, = (1.82 x 10 2 k2 L03/3 C*)\ p2 = (0.632 k7/6 L C„2) ■*", k = 2 It/X, A. is the wavelength, C„2 is the refractive index structure parameter, L is the mean propagation pathlength, and L, is the turbulence outer-scale. The transverse coherence length for a spherical wave is given by the well-known result p, = (0.546 k2 L C,,2)'3". For a nonuniform distribution of turbulence strength along the propagation path, C„2 in p, corre- sponds to a local value at a path position z = L; C02 in p, corresponds to a local value at a path position z = L; Cn2 in p2 represents a uniformly-weighted, path-integrated value; and C„2 in p, corresponds to a path-integrated value with a z weighting. For typical profiles of acoustic Cn2 with height, the echo power associated with the radio acoustic sounding of temperature does not appear to be significantly affected by the reduction in longitudinal coherence of the acoustic wave. WP-078 LOPEZ, R.E., R. ORTTZ, JA. AUGUSTINE, W.D. OTTO, and R.L. HOLLE. The progressive development of cloud-to-ground lightning in the early formative stages of a mesoscale convective complex. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, MA, 658-662 (1990). No abstract. WP-079 LOPEZ, RE., R. ORTTZ, W.D. OTTO, and R.L. HOLLE. The lightning activity and precipitation yield of convective cloud systems in central Florida. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, MA, 907-910 (1991). No abstract. 170 WP-080 LOPEZ, RE., W.D. OTTO, R. ORTIZ, and RX. HOLLE. The lightning characteristics of convective cloud systems in northeastern Colorado. Preprints, Conference on Atmospheric Electricity, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, MA, 727-731 (1990). No abstract. WP-081 MARTNER, BE. Development of the bright band in a freezing rain storm. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, MA, 813-816 (1991). No abstract. WP-082 MARTNER, BE., R.J. ZAMORA, J.B. SNIDER, P.I. Joe, and R. Caiazza. Evolution of a freezing rainstorm - Part II: Remote sensor observations. Proceedings, 1st International Symposium on Winter Storms, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, MA, 264-269 (1991). No abstract. WP-083 Mathews, Jr., G.M., and J.E. GAYNOR. The contribution of meteorology to visibility in a valley in the lee of the Rocky Mountains. Preprints, 7th Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, MA, 202-204 (1991). No abstract. WP-084 Matrosov, S.Y. Prospects for the measurement of ice cloud particle shape and orientation with elliptically polarized radar signals. Radio Science, 26(4):847-856 (1991). A method to estimate cloud particle orientation and shape parameters using a polarization diversity radar is presented. The method is demonstrated for low-reflectivity ice clouds containing crystals that are modeled as prolate and oblate spheroids. The parameters to be estimated are the particle mean canting angle and the axis ratio in the incident wave polarization plane. The scattering matrix concept is used to obtain a relationship between two orthogonally polarized received powers and the parameters of interest. It is shown that the use of an elliptically polarized radar signal diminishes the expected difference between received powers in the two receiving polarization channels. This makes polarization studies of ice clouds with relatively low reflectivities possible; these clouds often are "invisible" in one of the receiving channels when conventional linear or circular polarization is used. An estimation of errors in the retrieved mean canting angle vaiue caused by the spread in particle orientation is also given. WP-085 Matrosov, S.Y. Theoretical study of radar polarization parameters obtained from cirrus clouds. Journal of the Atmospheric Sciences. 48(8): 1062- 1070 (1991). A theoretical investigation of radar polarization parameters that characterize cloud ice backsc altering is presented. The parameters considered were those commonly used in radar polarimetrics such as differential reflectivity (ZdR), linear depolarization ratio (LDR), circular depolarization ratio (CDR), intrinsic degree of orientation (ORTT), as well as conventional reflectivities. Experimental data on the shapes of ice crystals and their orientations are taken into account Results suggest that prolate-shaped scatterers can be distinguished from those having oblate shapes by analyzing the depolarization ratio dependence on the elevation angle. Calculations suggest that circular polarization parameters provide stronger signals in a cross-polar channel and also show a lesser dependence on scatterer orientation in comparison with linear polarization parameters. Propagation effects do not significantly affect the polarization parameters for equivalent water contents and cloud thicknesses that are typical for cirrus clouds. Differential phase shift that might be observed in cirrus clouds is relatively small. Finally, equivalent reflectivity factors are analyzed for several ice particle types as a function of their major axis. Reflectivity dependence on particle shapes is demonstrated, and comments on the possibility of making approximate estimates of cloud particle sizes are given. 171 WP-086 May, P.T. Spaced antenna versus Doppler radars: A comparison of techniques revisited. Radio Science, 25(6): 1111-1119 (1990). The Doppler beam-swinging (DBS) and the spaced antenna (SA) techniques for radar wind measurement are compared on theoretical and practical grounds. It is shown that the information content is similar for both techniques and that errors introduced by horizontal variations of the transmitting and receiving antennas is derived, and it is shown that the backscattered power is proportional to an equivalent area. The equivalent area is equal to the antennas' physical area for a monostatic radar and is twice the area of the smallest antenna in the limit of one antenna being much larger than the other. Other factors affecting the techniques' sensitivity and accuracy are discussed. VHF radars operating at about 50 MHz should give similar sensitivity using both techniques, but for UHF wind profilers the DBS method is preferable. WP-087 Meitin, R.J., and RA. BROWN. A dual-Doppler analysis of North Dakota thunderstorms using airborne and ground-based radars. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, MA, 225-230 (1990). No abstract. WP-088 Meitin, RJ-, RA. BROWN, and J.G. MEl'l'lN. Comparison of airborne dual-Doppler and airborne/ground-based dual-Doppler analyses of North Dakota thunderstorms. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, MA, 474-477 (1991). No abstract. WP-089 Menzies, R.T., and MJ. POST. GLOBE backscatter: climatologies and mission results. Proceedings, International Symposium on High Power Lasers, Los Angeles, CA, January 20-25, 1991. Society of Photo-Optical Instrumentation Engineers, Bellingham, WA. SPIE Vol. 1416, 139-146(1991). The Global Backscatter Experiment (GLOBE) objectives require intensive study of the global climatology of atmospheric aerosol backscatter at infrared wavelengths. The data obtained from GLOBE are of great importance for analysis of the global winds measurement application of coherent Doppler lidar. Ground-based and airborne backscatter lidars have been developed to measure atmospheric backscatter profiles at C02 laser wavelengths. Descriptions of the calibration methodologies and selected measurement results are presented. WP-090 Mestayer, P.G., SJE. Larsen, C.W. FAIRALL, and J.B. Edson. Turbulence sensor dynamic calibration using real time spectral computations. Journal of Atmospheric and Oceanic Technology, 7(6):84 1-851 (1990). The integration of plug-in FFT boards in data acquisition computers allows a considerable development in the dynamic calibration of turbulence sensors. The spectral transfer function of a fast and sensitive turbulence sensor can be obtained in situ from a slow sensor having an absolute calibration, by computing in real time either the power spectra of the two signals or their complex cross-spectrum. The real time spectral method allows calibration of sensors with relatively complex responses and, in most cases, nonlinear transfer functions. When used in conjunction with appropriate control and correction algorithms, this method can take care of numerous sources of error such as electronic noise, line pickup, and sensor malfunctions. We show that it can be extended to sensor arrays, including X-wire dual-component anemometers. WP-091 Moore, D.I., C.N. Dahm, J.R. Gosz, and R.J. HILL. Use of long-path FTIR spectrometry in conjunction with scintillometry to measure gas fluxes. Proceedings, 2nd International Symposium, Field Screening Methods for Hazardous Wastes and Toxic Chemicals, Las Vegas, NV, February 12-14, 1991. Life Systems, Inc., Cleveland, OH, 541-548 (1991). Fourier Transform Infrared (FTIR) spectrometry is rapidly becoming a technique of choice for analyzing volatile hazardous waste emissions. We have developed a field portable system that is capable of measuring gas concentrations at up to a 1-km pathlength. The advantage of such a system is that it can analyze samples virtually in real time for myriad compounds simultaneously without introduction of any artifacts from sample collection. Because detection sensitivity increases with path length, analysis of compounds can often be made down to ppb levels. While we have concentrated on measuring gas emissions from biologic sources, we are also capable of monitoring hazardous gas emissions that have characteristic infrared absorbance peaks in regions of the IR spectrum that are not dominated by water or C02. Numerous volatile organic compounds such as chlorinated hydrocarbons, aromatic hydrocarbons, alcohols, ketones, esters, ethers, and 172 aldehydes fall into this category. While gas concentrations are of interest, emission rates are needed to accurately evaluate waste sites. Ob- taining such flux rates has become the focal point of our research. Recently, the Wave Propagation Laboratory (WPL) at NOAA (Boulder, CO) has demonstrated that an optical-scintillation instrument can measure path-averaged momentum and heat fluxes. Development of scintillometers by WPL, which is currently in progress, will allow long-path measurement of water flux as well. Combining these long-path flux measurements with measurements of gradients of gas concentrations using the FTTR has the potential to provide an estimate of flux rates for numerous gases simultaneously. This technique will then have applications in natural, agricultural, and human impacted areas such as landfills and hazardous waste sites. WP-092 MORAN, KJ*., RG. STRAUCH, and P.T. May. Lower tropospheric temperature profiling. Proceedings, 25th International Radar Conference, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, MA, 237-240 (1991). No abstract. WP-093 MORAN, K.P., RG. STRAUCH, B.L. WEBER, and D.B. WUERTZ. Wind profilers for mid-tropospheric sounding systems. Extended Abstracts, Symposium on Lower Tropospheric Profiling: Needs and Technologies, Boulder, CO, September 10-13, 1991. American Meteorological Society, Boston, MA, 53-55 (1991). No abstract. WP-094 MORAN, KJ\, RG. STRAUCH, D.B. WUERTZ, and BL. WEBER Temperature measurements by RASS with a NOAA demonstration network profiler first results. Extended Abstracts, Symposium on Lower Tropospheric Profiling: Needs and Technologies, Boulder, CO, September 10-13, 1991. American Meteorological Society, Boston, MA, 91-92 (1991). No abstract. WP-095 MORAN, K.P., D.B. WUERTZ, R.G. STRAUCH, N.L. ABSHTRE, and D.C. LAW. Temperature sounding with wind profiler radars. Journal of Atmospheric and Oceanic Technology, 8:606-608 (1991). A network of 31 radar wind profilers is being installed in the central United States by the National Oceanic and Atmospheric Administration (NOAA). The radars are expected to measure the vertical profile of horizontal and vertical wind starting at 500 m above the surface (AGL) and extending to about 16 km AGL. These 404.37-MHz radars can also be adapted to measure virtual temperature profiles in the lower troposphere by the radio acoustic sounding system (RASS) technique. RASS experiments were conducted using the prototype radar of the NOAA network, and results showed that virtual temperature profiles can be measured starting at 500 m AGL (the lowest height observed with this radar) and extending to 3.5-5.2 km AGL. WP-096 NEFF, WD., J£. GAYNOR and J. Ye. The effect of sodar beamwander and tilt on Doppler-derived turbulence measurements. Preprints, 7th Symposium on Meteorological Observations and Instrumentation, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, MA, 422-427 (1991). No abstract. WP-097 NEFF, WD., JR. JORDAN, J.E, GAYNOR, D.E. WOLFE, WJL. ECKLUND, DA. CARTER and K.S. GAGE. The use of 915 MHz wind profilers in complex terrain and regional air quality studies. Preprints, 7th Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA January 14-18, 1991. American Meteorological Society, Boston, MA, J230-J233 (1991). No abstract. 173 WP-098 NEIMAN, P.J., P.T. May, and MA. SHAPIRO. Radio acoustic sounding system and wind profiler observations of fronts in the lower and middle troposphere. Preprints, 7th Symposium on Meteorological Observations and Instrumentation, New Orleans, LA, January 14- 18, 1991. American Meteorological Society, Boston, MA, 61-66 (1991). No abstract. WP-099 NEIMAN, P.J., P.T. May, B.B. STANKOV, and MA. SHAPIRO. Radio acoustic sounding system observations of an Arctic front Journal of Applied Meteorology, 30(6):881-892 (1991). A radio acoustic sounding system (RASS), coupled with the NOAA/Wave Propagation Laboratory 915-MHz wind profiler, observed an arctic front and arctic air mass that passed over Denver, Colorado, between 1 and 5 February 1989. The RASS temperature measurements extended to approximately 1.5 km above ground level and were taken at 15-min intervals during the frontal passage and at 1-h intervals thereafter. During the frontal passage on 1 February, the RASS documented a temperature decrease of >15° C. The succeeding cold air ( — 20° to -40° Q over Denver never exceeded 1.3 km in depth. The frontal inversion at the top of the cold air mass was 300 m in depth and possessed large static stability [-d6/dp - 80 K (100 mb)1] and vertical wind shear [- dV/9p - 30 m s"1 (100 mb)"1. Temporal fluctuations (-3 h) in the depth of the cold air were observed by the RASS between the operational 12-h rawinsonde observing periods. Simultaneous RASS and rawinsonde measurements showed good agreement with regard to key thermal features. WP-100 NEIMAN, P.J., MA. SHAPIRO, and L.S. FEDOR. Synoptic and mesoscale frontal characteristics within an intense extratropical marine cyclone: ERICA 10P4, January 4-5, 1989. Proceedings, 1st International Winter Storms Symposium, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, MA, 108-114 (1991). No abstract. WP-101 Nishiyama, R.T., and AJ. BEDARD, JR. A "quad-disc" static pressure probe for measurement in adverse atmospheres: with a comparative review of static pressure probe designs. Review of Scientific Instruments, 62(9):2 193-2204 (1991). There are many areas of need for accurate measurements of atmospheric static pressure. These include observations of surface meteorology, airport altimeter settings, pressure distributions around buildings, moving measurement platforms, as well as basic measurements of fluctuating pressures in turbulence. Most of these observations require long-term observations in adverse environments (e.g., rain, dust, or snow). Currently, many pressure measurements are made, of necessity, within buildings, thus involving potential errors of several millibars in mean pressure during moderate winds, accompanied by large fluctuating pressures induced by the structure. In response to these needs, we designed a "Quad-Disc" pressure probe for continuous, outdoor monitoring purposes which is inherently weather protected. This Quad-Disc probe has the desirable features of omnidirectional response and small error in pitch. A review of past static pressure probes contrasts design approaches and capabilities. WP-102 OLIVIER L.D., and R.M. BANT A. Doppler lidar measurements of wind flow and aerosol concentration at the Grand Canyon. Technical Digest, series vol. 12, Coherent Laser Radar: Technology and Applications Topical Meeting, Snowmass, CO, July 8-12, 1991. Optical Society of America, Washington, DC, 181-184 (1991). No abstract. WP-103 OLIVIER, L.D., J.M. Intrieri, and RM. BANTA. Doppler lidar observations of a land/sea breeze transition on a day with offshore flow. Preprints, 5th Conference on the Meteorology and Oceanography of the Coastal Zone, Miami, FL, May 6-9, 1991. American Meteorological Society, Boston, MA, 138-142 (1991). No abstract. WP-104 ORR, B.W. Boundary layer momentum budgets as determined from a single scanning Doppler radar. Master's Thesis, Colorado State University, Fort Collins, CO, 116 pp. (1990). 174 The Velocity Azimuth Display (VAD) technique is extended to third-order turbulent velocity statistics. By applying this extended VAD technique to a single scanning Doppler radar a solution for the horizontal turbulent momentum flux budget is obtained. All terms excluding the buoyancy, pressure and eddy dissipation terms can be solved for directly. High resolution measurements of the momentum flux budget can then be studied in both space and time. Specifically the third-order turbulent transport term can be examined. Three data sets characterized by hot, clear summertime planetary boundary layers (PBL) are analyzed using this extended VAD technique. These data show turbulent transport to be very significant throughout the day and night Daytime values were observed to be of the same order or slightly larger than shear production. At night shear production dominated but turbulent transport was still of significant magnitude. Other notable features were the high degree of variability in all turbulent quantities in both space and time. The large contribution from turbulent transport and the high degree of nonstationarity in the turbulence field are in contrast to most other field measurements. Brief explanations are given for these differences. Comparisons with computer modeling studies are also made which agree more closely with the radar analysis than did the field studies. WP-105 PALMER, AJ. Dual-frequency radar: Basic theory and surface current mapping performance for land-based systems. NOAA TM ERL WPL-186 (PB121251), 27 pp. (1990). I review the essential theoretical aspects of dual-frequency radar sensing of ocean surface currents. The review includes the basic single carrier frequency technique as well as the multiple carrier frequency technique used to improve the signal-to-noise ratio. I add to this review my calculation of the dependence of the signal-to-noise ratio on a finite time separation between the transmitted radar signals, and my calculations of the achievable surface -current resolution for land-based systems. Scaling relationships and resolution contours are plotted, which will help in the design of an optimal current mapping system. I conclude with a brief discussion of two new dual-frequency radar concepts: bistatic dual-frequency radar and dual-frequency sodar. WP-106 PALMER, A.J. Radiation-induced orientation of atmospheric aerosols. Journal of the Optical Society of America A, 8(2):366-369 (1991). A theoretical model is presented for computing the radiation-induced orientation of nonspherical particles in the atmosphere. This process is examined as a possible remote-sensing technique for determining size and shape characteristics of atmospheric aerosols. The theoretical model is applied to cirrus particles modeled as prolate dielectric spheroids. The radiation-induced perturbations in the average tip angle of the spheroids and in the backscattered depolarization ratio are computed for an assumed radiation flux of 5 mJ/cm2 for three different wavelengths. The computed perturbations are found to be approximately 30-40 dB down from the corresponding unperturbed values and appear marginally detectable by ground-based lidars. WP-107 Parsons, D.B., and RA. KROPFLI. The dynamics of microbursts as revealed by Doppler radar observations and numerical simulations. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, MA, 359-362 (1991). No abstract. WP-108 Parsons, D.B., M.A. SHAPIRO, RM. HARDESTY, RJ. ZAMORA, and J.M. Intrieri. The fine-scale structure of a West Texas dryline. Monthly Weather Review, 119(5):1242-1258 (1991). During spring and early summer, a surface confluence zone, often referred to as the dryline, forms in the midwestern United States between continental and maritime air masses. The dew point temperature across the dryline can vary in excess of 18°C in a distance of less than 10 km. The movement of the dryline varies diurnally with boundary layer growth over sloping terrain leading to an eastward apparent propagation of the dryline during the day and a westward advection or retrogression during the evening hours. In this study, we examine the fine-scale structure of a retrogressing dryline using data taken by a Doppler lidar, a dual-channel radiometer, and serial rawinsonde ascents. While many previous studies were unable to accurately measure the vertical motions in the vicinity of the dryline, our lidar measurements suggest that the convergence at the dryline is quite intense with maximum vertical motions of -5 m s'1. The winds obtained from the Doppler lidar measurements were combined with the equations of motion to derive perturbation fields of pressure and virtual potential temperature (80). Our observations indicate that the circulations associated with this retrogressing dryline were dominated by hot, dry air riding over a westward moving denser, moist flow in a manner similar to a density current Gravity waves were observed above the dryline interface. Previous observational and numerical studies have shown that differential heating across the dryline may sometimes enhance regional pressure gradients and thus impact dryline movement. We propose that this regional gradient in surface heating in the presence of a confluent flow results in our observed intense wind shifts and large horizontal gradients in 6y across the dryline. The local gradient in 9, 175 influences the movement and flow characteristics of the dryline interface. We feel that this study is one of the most complete and novel uses of Doppler lidar to date. WP-109 Pearson, G.N. The design and performance characteristics of a compact C02 Doppler lidar transmitter. Proceedings, Laser Radar Conference VI, Los Angeles, CA, January 23-25, 1991. Society of Photo-Optical Instrumentation Engineers, Bellingham, WA, 147-150 (1991). A novel, high prf CO, Doppler lidar is described which has been designed to make range resolved velocity and DIAL measurements out to ranges of 3-5 km. Details of the design are given and some preliminary test results are presented. WP-110 Pearson, G.N., B.J. Rye, and R.M. HARDESTY. The design and performance of a mini-MOPA C02 Doppler lidar transceiver for atmospheric monitoring. Technical Digest, series vol. 12, Coherent Laser Radar Technology and Applications Topical Meeting, Snowmass, CO, July 8-12, 1991, 64-65 (1991). No abstract. WP-111 Penc, R.S., S JL Williams, B.A. Albrecht, R Caiazza, and RJ\ REINKING. Lake-effect storms east of Lake Ontario: Some preliminary findings from the LOWS field project Preprints, 1st International Symposium on Winter Storms, New Orleans, LA, January 14-16, 1991. American Meteorological Society, Boston, MA, 252-257 (1991). No abstract. WP-112 POST, M _L, and R-E. CUPP. The effects of C02 gain-switched spikes on estimating lidar Doppler shifts. Technical Digest, series vol. 12, Coherent Laser Radar: Technology and Applications Topical Meeting, Snowmass, CO, July 8-12, 1991. Optical Society of America, Washington, DC, 19-22 (1991). No abstract. WP-113 POST, MJ., and R£. CUPP. Optimizing a pulsed Doppler lidar. Applied Optics, 29(28):4145^158 (1990). NOAA's fieldable injection-seeded, pulsed, coherent C02 lidar was developed over a 5-year period. Its performance and reliability are characterized. Techniques for calibration, alignment, collimation, and for improving detector performance and frequency stability are presented. WP-114 REINKING, RF., RA. KROPFLI, R Caiazza, GJ>. Byrd, R. Ballentine, A. Stamm, R.S. Penc, T.A. Niziol, and C. Bedford. The Lake Ontario Winter Storms Project (LOWS). Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, MA, 613-618 (1990). No abstract. WP-115 REINKING, RF., RJ. Meiti'n, F. Kopp, and HD. Orville. Fields of motion and transport within a sheared thunderstorm. Preprints, 2nd International Meeting on Agriculture and Weather Modification, Zamora, Spain, March 12-15, 1991. International Committee on Agriculture and Atmospheric Modification, Zamora, Spain, 59-66 (1991). No abstract. 176 WP-U6 Rocken, C, J.M. Johnson, R.E. Neilan, M. Cerezo, J.R. JORDAN, MJ. FALLS, LD. Nelson, RJL Ware, and M. Hayes. The measure- ment of atmospheric water vapor: Radiometer comparison and spatial variations. EBB Transactions on Geosciences and Remote Sensing, 29(l):3-8 (1991). We conducted two Water Vapor Radiometer (WVR) experiments to evaluate whether such instruments are both suitable and needed to correct for propagation effects that are induced by precipitable water vapor (PWV) on signals from the Global Positioning System (GPS) and Very Long Baseline Interferometry (VLBI). WVRs are suitable for these corrections if they provide wet path delays to better than 0.5 cm. They are needed if spatial variations of PWV result in complicated, direction-dependent propagation effects that are too complex to be parameterized in the GPS or VLBI geodetic solution. In the first experiment we addressed the suitability of radiometers by comparing six WVRs at Stapleton International Airport for two weeks. While two WVRs showed an average wet path delay bias of only 0.1 cm, others were biased by 1-3 cm relative to each other and relative to radiosondes. The second experiment addressed the question whether radiometers are needed for the detection of inhomogeneities in the wet delay. Three JPL D-series radiometers were operated at three sites in Colorado approximately 50-km apart The WVRs simultaneously sampled PWV at different azimuths and elevations in search of spatial variations of PWV. On one day of this second experiment we found evidence for spatial variations of the wet path delay as high as 20% of the total wet path delay. WP-117 Ruffieux, D., and DJE. WOLFE. Differential surface energy budget in downtown Denver, Colorado. Preprints, 7th Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Waste Management Association, Pittsburgh, PA, 308-311 (1991). No abstract. WP-118 Russell, CA., and J.R. JORDAN. Portable clutter fence for UHF wind profiling radar. Preprints, 7th Symposium on Meteorological Observations and Instrumentation, Special Session on Laser Atmospheric Studies, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, MA, J152-J156 (1991). No abstract. WP-119 Rye, BJ. Spectral correlation of atmospheric lidar returns with range-dependent backscatter. Journal of the Optical Society of America A, 7(12):2 199-2207 (1990). Expressions are derived for the spectrum of atmospheric backscatter coherent lidar returns in the presence of arbitrary line-of-sight backscatter nonuniformities. It is shown that, in contrast to microwave weather radar, sample measurement spectra are smoothed, although mean spectra and therefore the first-order coherence of the return are unaffected. Simulated data are used to demonstrate that estimates of return power are degraded by sampling smoothing, but some estimates of mean Doppler shift are improved. WP-120 Rye, B J., and R.G. Frehlich. The truncated Gaussian lidar antenna problem revisited. Technical Digest, series vol. 12, Coherent Laser Radar Technology and Applications Topical Meeting, Snowmass, CO, July 8-12, 1991. Optical Society of America, Washington, DC, 165-168(1991). No abstract. WP-121 Rye, B J., and R.M. HARDESTY. Power estimator bias in filtered incoherent backscatter heterodyne lidar returns. Technical Digest, series vol. 12, Coherent Laser Radar: Topical Meeting on Technology and Applications, Snowmass, CO, July 8-12, 1991. Optical Society of America, Washington, DC, 270-272 (1991). No abstract. WP-122 Sarma, AD., and RS. Cole. Effect of multipath and snow on millimeter wave scintillations on a 4.1-km line-of-sight link. Journal of Atmospheric and Terrestrial Physics, 53(5):369-378 (1991). 177 Multipath propagation can occur for various reasons. For example, it can be due to sudden changes in the refractive index of the propagation medium or to reflections from melting snow/ice. We find that dry snow, or even 'moist' snow at 0°C, has no measurable effect on the propagation of radio waves up to at least 54.5 GHz. When multipath propagation occurs, the low frequency part of the scintillation spectrum is distorted. The usual theoretical predictions applicable to line-of-sight millimeter wave propagation through clear air turbulence must be used with caution when the scintillations of the propagating signals are a result of multipath effects. It is also noted that propagation through vegetation greatly distorts the clear-air scintillation spectrum. Saturation of scintillations, which can also dramatically alter the scintillation spectrum, is not expected to be a problem for millimeter wave propagation over line-of-sight paths. WP-123 Sarma, AX)., and R.J. HILL. Effect of blowing snow and ground blizzards on millimeter wave scintillation spectra. International Journal of Infrared and Millimeter Waves, 12(9), 997-1022 (1991). We describe the effect of ground blizzards and blowing snow on millimeter wave scintillation spectra at 116 and 230 GHz. During snowstorms, multipath propagation can occur for various reasons. Whatever the reason for the multipath, it will affect the scintillation spectrum. Enhancement of the scintillation spectrum is observed at both low and high temporal frequencies. In some cases, two additional comer frequencies are evident at the high-frequency end of the scintillation spectrum. The method of obtaining the cross-path wind component fails when the wind is nearly parallel to the propagation path. WP-124 Sarma, AT)., RJ. HILL, and R.J. LATAJTTS. Effect of rain on millimeter wave amplitude scintillation spectra. In Millimeter Wave and Microwave, International Conference on Millimeter Wave and Microwave, ICOMM-90, Dehradun, India, December 19-21, 1990. Tata McGraw-Hill, New Delhi, India, 587-590 (1990). Two spectra corresponding to 230-GHz millimeter wave data taken during light precipitation are presented. We find that the rain-induced scintillations are distributed over a wider frequency band than the tropospheric turbulence-induced scintillations. This introduces two additional corner frequencies at the high-frequency ends of the spectra. These effects will have important implications for millimeter wave systems design. WP-125 Sassen, K., C.J. GRUND, J. Spinhime, RM. HARDESTY, and J.M. Alvarez. The 27-28 October 1986 FIRE IFO cirrus case study: a five- lidar overview of cloud structure and evolution. Monthly Weather Review, 118:2288-2311 (1990). Optical remote sensing measurements of cirrus cloud properties were collected by one airborne and four ground-based lidar systems over a 32-h period during this case study from the First ISCCP (International Satellite Cloud Climatology Program) Regional Experiment (FIRE) Intensive Field Observations (IFO) program. The lidar systems were variously equipped to collect linear depolarization, intrinsically calibrated backscatter, and Doppler velocity information. Data presented here describe the temporal evolution and spatial distribution of cirrus clouds over an area encompassing southern and central Wisconsin. The cirrus cloud types include: (a) dissipating subvisual and "thin" fibrous cirrus cloud bands, (b) an isolated mesoscale uncinus complex (MUC), (c) a large-scale, deep cloud that developed into an organized cirrus structure within the lidar array, and (d) a series of intensifying mesoscale cirrus cloud masses. Although the cirrus frequently developed in the vertical from particle fallstreaks emanating from generating regions at or near cloud tops, glaciating supercooled (-30° to -35°C) altocumulus clouds contributed to the production of ice mass at the base of the deep cirrus cloud, apparently even through riming, and other mechanisms involving evaporation, wave motions, and radiative effects, are indicated. The generating regions ranged in scale from -1.0-km cirrus uncinus cells to organized MUC structures up to -120 km across. WP-126 SCHROEDER JA., E.R. WESTWATER, P.T. May, and L.M. McMillan. Prospects for temperature sounding with satellite and ground- based RASS measurements. Journal of Atmospheric and Oceanic Technology, 8(4):506-513 (1991). Temperature profiles from the Tiros-n Operational Vertical Sounder (TOVS) were combined with low-altitude virtual temperature profiles measured by a ground-based 915-MHz/2-kHz Radio-Acoustic Sounding System (RASS) at Denver, Colorado. Low-level temperature inversions of more than 20°C in 100 m, as measured by radiosonde, were successfully resolved by RASS, providing critical information that TOVS alone could not. Conversely, TOVS augmented the RASS altitude coverage, which was typically limited to the first 1-2 km above ground, due to strong acoustic attenuation at 2 kHz (a 405-MHz/.9-kHz RASS measured to significantly higher altitudes). The complementa- ry nature of TOVS and RASS is demonstrated with examples chosen from extreme cases that illustrate the capabilities and limitations of the separate and combined systems. 178 WP-127 Shang, E.C., and Y.Y. Wang. Environmental mismatching effects on source localization processing in mode space. Journal of the Acoustical Society of America, 89(5):2285-2290 (1991). In this paper the source localization performance degradation of the matched field processing (MFP) caused by environmental mismatch has been discussed for HRMM processor [E. C. Shang, J. Acoust. Soc. Am., 86, 1960-1964 (1989)] in mode space analytically. By using the approximate modal eigenvalue solution, the analytic expressions for describing the impacts of water-depth mismatch in a Pekeris waveguide and sediment-type mismatch have been derived. By using the modal perturbation theory an indicator for assessing the range performance degradation caused by sound-speed profile (SSP) mismatch has been proposed. Analytic results have been verified by numerical simulations. WP-128 Shang, E.C., and Y.Y. Wang. Ocean acoustic field simulations for monitoring large-scale ocean structures. Computer Physics Communications, 65(l-3):238-245 (1991). Substantial numerical simulations of low-frequency acoustic field under different ocean models have been carried out on CYBER-205 at WPL/NOAA. The purpose of these numerical simulations is to investigate our potential ability to monitor large-scale ocean structures by using modal ocean acoustic tomography (MOAT). For example, the possibility of monitoring El Nino by using MOAT has been illustrated. WP-129 SHAPIRO, MA., E.G. DONALL, PJ. NEMAN, L.S. FEDOR and N. Gonzalez. Recent refinements in the conceptual models of extratropical cyclones. Proceedings, 1st International Winter Storms Symposium, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, MA, 6-14 (1991). No abstract. WP-130 SHAPIRO, MA., and D. Keyser. Fronts, jet streams and the tropopause. In Extratropical Cyclones, The Erik Palme'n Memorial Volume, C.W. Newton and E.O. Holopainen, (eds.), American Meteorological Society, Boston, MA, 167-183 (1990). No abstract. WP-131 SHAW, JA. Calibration of infrared radiometers for cloud-base temperature remote sensing: Technique and error analysis. NOAA TM ERL WPL-207, 17 pp. (1991). Absolute radiometric calibration is required for ground-based infrared remote sensing of cloud-base temperature. This requires associating the radiometer's output voltage with blackbody temperatures over the desired measurement range. Insufficient attention to subtle error sources while performing this conceptually simple calibration results in errors many times larger than the 1.0°C uncertainty achievable with a carefully performed calibration. Inadequate blackbody simulation and imprecise voltage measurements contribute most significantly to calibration uncertainty. The purpose of this report is documentation and error analysis of the technique used at the NOAA Wave Propagation Laboratory for calibrating zenith-viewing infrared radiometers. Additional uncertainties that arise in cloud-base temperature measurements for real clouds in the real atmosphere are discussed briefly. WP-132 SHAW, JA., and E.R. WESTWATER. Passive remote sensing of boundary layer temperature and water vapor. Preprints, 7th Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorologi- cal Society, Boston, MA Jl 16-J1 19 (1991). Passive observations of temperature and water vapor from space have been made traditionally by both infrared and microwave sensors (Phillips et ah 1979). Microwave radiometers have poorer horizontal and vertical resolution than infrared instruments but they provide sounding during cloudy conditions. The combination of measurements from the two wavelength regions yields a nearly all-weather sounding system. In this paper, we describe a passive ground-based microwave and infrared system that has potential of providing nearly all-weather remote sensing of low-altitude temperature and water vapor. We also discuss combining such passive systems with a ceilometer. 179 WP-133 SNIDER, J.B., MD. JACOBSON, R.H. BEELER, and D.A. HAZEN. Comparison of OLYMPUS beacon and radiometric attenuation measurements at Blacksburg, Virginia. Proceedings, 15th NASA Propagation Experimenters' Meeting (NAPEX XV), London, Ontario, Canada, June 28-29, 1991. Jet Propulsion Laboratory/NASA, Pasadena, CA/Washington, DC, 116-122 (1991). Measurements of attenuation of the 20 and 30 GHz beacons on board the OLYMPUS satellite are compared to simultaneous observations of atmospheric attenuation by a multichannel microwave radiometer along the same path. Departures from high correlation between the two measurements are believed to be related to differences in antenna beamwidths. Mean equivalent zenith attenuations derived from the slant path data are compared to zenith observations made at previous locations. WP-134 STANKOV, B.B., J.A. SCHROEDER, L.S. FEDOR, and E.R. WESTWATER. Temperature and humidity profiling with ground-based RASS and space-based TOVS data. Preprints, Symposium on Lower Tropospheric Profiling: Needs and Technologies, Boulder, CO, September 10-13, 1991. American Meteorological Society, Boston, MA, 213 (1991). No abstract. WP-135 STANKOV, B.B., J.A. SCHROEDER, E.R. WESTWATER, and R.M. Rasmussen. Liquid water profiling using remote sensor observations. Preprints, 4th International Conference on Aviation Weather Systems, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, MA, 239-246 (1991). Two-channel microwave radiometers have been used to measure the integrated amount of liquid in non-precipitating clouds for nearly 10 years (Westwater, 1990). In 1980, Hogg et al. (1983b) reported a single case where radiometer measurements of integrated liquid coincided with aircraft icing reported by pilots (PIREPS). In that case, below-freezing surface temperatures led to the assumption that the liquid observed by the radiometers was supercooled. These initial observations motivated a comparison of two years of radiometer observations at Stapleton International Airport in Denver, Colorado, with icing PIREPS within a 50-nmi radius of Stapleton (Popa Fotino et al. 1986). Despite the ambiguous nature of the reported icing locations, more than 90% of the reported icing conditions within 20 nmi of the radiometer were identified by a discriminant analysis technique that employed radiometer liquid measurements and surface temperatures. WP-136 STANKOV, B.B., J.A. SCHROEDER, EJR. WESTWATER, BX. WEBER, and RM. Rasmussen. Profiling lower-tropospheric water substance with combined sensors. Extended Abstracts, Symposium on Lower Tropospheric Profiling: Needs and Technologies, Boulder, CO, September 10-13, 1991. American Meteorological Society, Boston, MA, 211-212 (1991). No abstract. WP-137 STANKOV, B.B., E.R. WESTWATER, J.B. SNIDER, and BL. WEBER. Remote sensor observations during WISP-90: The use of microwave radiometers, RASS, and ceilometers for detection of aircraft icing conditions. NOAA TM ERL WPL-187 (PB131839), 77 pp. (1990). During February and March 1990, the National Center for Atmospheric Research, the NOAA Wave Propagation Laboratory, and the NOAA Forecast Systems Laboratory conducted the Winter Icing and Storms Project (WISP). One of the principal objectives was to determine the utility of unattended microwave radiometers in detecting atmospheric liquid water and providing input to forecasts of aircraft icing. Arrays of microwave radiometers, infrared radiometers, lidar ceilometers, and radio-acoustic sounding systems were used to determine spatial and temporal distribution of super-cooled liquid water. Results are presented from four representative cases to demonstrate that the integrated system, which comprises a microwave water substance radiometer, a radio-acoustic sounding system, and a ceilometer, can identify super-cooled liquid water. Occasional outages because of environmental effects on the radiometer antenna were encountered, and quality control procedures were employed to detect erroneous data. Outage statistics are presented; 15% of the data obtained during 10 WISP intensive observation periods were rejected. Recommendations to improve system performance and usage for future experiments are presented. WP-138 STRAUCH, R.G., K J>. MORAN, and P.T. May. RASS temperature ei-rors caused by winds. Preprints, 7th Symposium on Meteorological Observations and Instrumentation; Special Session on Lower Atmospheric Studies, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, MA, 51-54 (1991). 180 The Radio Acoustic Sounding System (RASS) has received renewed attention in the United States recently because RASS can be added to existing wind profilers with relatively low cost and effort to measure vertical profiles of virtual temperature in the lower troposphere. Rapid progress in applying RASS to wind profilers has been made since 1987 when RASS research was revived in the United States. The RASS technique used with wind profilers is well understood (May et al. 1990), and methods for installing RASS on wind profilers have been documented (Strauch et al. 1989). The accuracy of RASS temperature measurements has been verified by radiosonde comparisons (May et al. 1989), and RASS/wind profiler data are being used in meteorological research studies (e.g., Neiman et al. 1990). The Wave Propagation Laboratory (WPL) has had RASS systems operating routinely since April 1989, and RASS has been demonstrated on the prototype of the new NOAA wind profiler radar (Moran et al. 1990). An effort is underway to determine whether combined RASS/satellite radiometer instruments can produce temperature soundings suitable for many meteorological applications. In this paper we examine errors that winds and turbulence can cause in RASS temperature data measured with wind profilers. WP-139 Tatarskii, V.I., and M.M. Dubovikov. The spectrum of velocity and refractive turbulence in the viscous and viscous-diffusive range. Proceedings, ICO Topical Meeting on Atmospheric, Volume and Surface Scattering and Propagation, Florence, Italy, August 27-30, 1991. University of Florence, Florence, Italy, 371-374 (1991). No abstract. WP-140 Walsh, EJ. Surface contour radar directional wave spectra measurements during LEWEX. In Directional Ocean Wave Spectra, Robert C. Beal, (ed.), Johns Hopkins University Press, Baltimore, MD, 86-90 (1991). Measurements of directional wave spectra made with the surface contour radar in March 1987 are presented and analyzed. The spatial variation of the propagation directions on each day is used to suggest possible source regions of the wave fields. The results are also used to infer the temporal variability that might be sensed by stationary in situ instruments. WP-141 WEBER, B.L., D.B. WUERTZ, P.T. May, R.G. STRAUCH, DA. MERRJTT, and K.P. MORAN. Ocean surface current measurements with a single station, Doppler/spaced-antenna radar. NOAA TM ERL WPL-190 (PB142307), 18 pp. (1990). We conducted a preliminary experiment to determine the feasibility of using one radar to measure the two-dimensional ocean surface current. The Doppler method was used to measure the radial component and the Spaced Antenna (SA) method was used to measure the transverse component of the current This dual method produced current measurements that showed consistency over range and time, demonstrating potential for the technique. However, the experiment also raised some questions. On occasions, the SA method seemed to be very sensitive to noise, producing apparently erroneous results. Therefore, we have planned a more definitive experiment with improved radar antennas, with improved data acquisition, and with independent current observations for comparisons. WP-142 WEBER, B.L., D.B. WUERTZ, R.G. STRAUCH, D.A. MERRITT, K.P. MORAN D.C. LAW, D. VAN DE KAMP, R.B. CHADWICK, MM. ACKLEY, M.F. BARTH, N.L. ABSHIRE, PA. MILLER, and T.W. SCHLATTER. Preliminary evaluation of the first NOAA demonstration network wind profiler. Journal of Atmospheric and Oceanic Technology, 7(6):909-918 (1990). The first wind profiler for a demonstration network of wind profilers recently passed the milestone of 300 h of continuous operation. The horizontal wind component measurements taken during that period are compared with the WPL Platteville wind profiler and the NWS Denver rawinsonde. The differences between the network and WPL wind profilers have standard deviations of 2.30 m s'1 and 2.16 m s"' for the u- and v-components, respectively. However, the WPL wind profiler ignores vertical velocity, whereas the network radar measures it and removes its effects from the u- and v-component measurements. The differences between the network wind profiler and the NWS rawinsonde (separated spatially by about 50 km) have standard deviations of 3.65 m s"1 and 3.06 m s"' for the u- and v-components, respectively. These results are similar to those found in earlier comparison studies. Finally, the new network wind profiler demonstrates excellent sensitivity, consistently reporting measurements at all heights msl from 2 to nearly 18 km with very few outages. WP-143 Weickmann, A.M. BETA: A program for calculating and archiving backscatter profiles. NOAA TM ERL WPL-200, 114 pp. (1991). BETA is a FORTRAN program that processes signal data from the NOAA coherent lidar and creates and archives aerosol backscatter profiles. This document focuses on the program software and its execution. 181 WP-144 WELSH, D.C. Use of the UNIX system: Beginner's guide. NOAA TM ERL WPL-208, 20 pp. (1991). A guide for the new user on a Sun UNIX computer is presented. A brief history of UNIX is presented. The background concepts of UNIX are presented next for input, output, and the file system. Finally, UNIX commands are presented, grouped by function: directory, file network, and miscellaneous. WP-145 WESTWATER, E.IL, and M.J. FALLS. Brightness temperature and attenuation statistics at 20.6 and 31.65 GHz. Proceedings, 15th NASA Propagation Experimenters' Meeting (NAPEX XV), London, Ontario, Canada, June 28-29, 1991. Jet Propulsion Labor- atory/NASA Pasadena, C A/Washington, DC, 107-115 (1991). Attenuation and brightness temperature statistics at 20.6 and 31.65 GHz are analyzed for a year's data that were collected in 1988 at Denver, and Platteville, Colorado. The locations are separated by 49 km. Single-station statistics are derived for the entire year. Quality control procedures are discussed and examples of their application are given. WP-146 WESTWATER, E.R., and L.S. FEDOR. The validation of microwave spaceborne observations by surface-based remote sensors. Global and Planetary Change, 90:247-252 (1991). Passive microwave observations from polar-orbiting satellites provide meteorologically-important information on temperature profiles, water vapor, and cloud liquid. The variable measured by radiometers is radiance, or brightness temperature, as a function of frequency, viewing angle, and polarization. Meteorological parameters are then extracted from the radiance measurements by retrieval algorithms. The utility of these parameters, both in operational meteorology and in monitoring climate change, depends on the calibration and stability of the instrument, and on the type of retrieval algorithm that is used. Ultimately, the derived parameters must be compared with ground-truth. For temperature and water vapor soundings, radiosondes are frequently used for validation and calibration. However, for the climatically- important variable cloud liquid, conventional measurements are not adequate, and surface- and aircraft-based remote sensor measurements are required. In this paper, calibration of microwave instruments is discussed and comparisons with various sources of ground-truth are presented. In addition, a possible role for surface-based remote sounders in the calibration and validation of satellite products is suggested. These remote sounders include microwave radiometers, wind profilers, and Radio Acoustic Sounding Systems (RASS). WP-147 WESTWATER, E.R., J.B. SNIDER, and MJ. FALLS. Ground-based radiometric observations of atmospheric emission and attenuation at 20.6, 31.65, and 90.0 GHz: a comparison of measurements and theory. Ibhti Transactions on Antennas and Propagation, 38(10): 1569- 1580 (1990). During 1987 and 1988, ground-based zenith-viewing observations of atmospheric thermal emission were made at frequencies of 20.6, 3 1 .65 and 90.0 GHz. At the locations of the experiments — San Nicholas Island, CA, and Denver CO — radiosonde observations of temperature and humidity were also available. Both National Weather Service and CLASS radiosondes were used in the study. The data, after conversion to attenuation by use of the mean radiating temperature approximation, were processed to derive attenuation statistics. Both clear and cloudy attenuation characteristics were examined and compared with results from recent theories. For the clear atmosphere, water vapor models of Waters and of Liebe were compared. At 20.6 and 31.65 GHz, the model of Waters agrees better with measurements; at 90.0 GHz, the model of Liebe is far superior. A recent model of Rosenkranz was used for oxygen absorption. For the average mass absorption coefficients for liquid clouds, measurement and theory generally agreed to within 30%. The predictability and interdependence of the three separate channels were also examined. It was found that attenuation for any two channels can predict the third to within 25%. WP-148 White, A.B., and C.W. FAIRALL. Convective boundary layer structure observed during ROSE-I using the NOAA 915 MHz radar wind profiler. NOAA TM ERL WPL-205, 58 pp. (1991). Time series of radar wind profiler and sodar reflectivity data were analyzed to extract a continuous record of mixing depths in the convective planetary boundary layer. Results indicate that radar signal-to-noise ratio (SNR) data can be used to successfully monitor the elevated inversion heights associated with convective development. Mixing depths in the lowest 200 m (i.e. occurring at night) were determined from sodar facsimile records. In addition to the SNR, vertical velocities and Doppler spectral widths measured by the radar were analyzed to further define CPBL structure. Profiles of vertical velocity variance and skewness derived from high temporal resolution radar data agree with previous observations. The radar-derived skewness profile also indicates a peak in skewness just below the height of the capping inversion. Although previously unobserved, this feature occurs frequently in large eddy simulation model results. Estimates of the turbulence kinetic energy dissipation rate determined from radar spectral widths appear to be about a factor of two too low. 182 WP-149 White, A.B., C.W. FATRALL, and D£. WOLFE. Use of 915 MHz wind profiler data to describe the diurnal variability of the mixed layer. Preprints, 7th Joint Conference on Applications of Air Pollution Meteorology with AWMA, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, MA, J161-J166 (1991). No abstract. WP-150 WILCZAK, J.M., and T. W. Christian. A vorticity analysis of the non-supercell, 02 July 1987 tornado. Preprints, 16th Conference on Severe Local Storms (Special Sessions on Artificial Intelligence), Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society,. Boston, MA, 560-565 (1990). No abstract. WP-151 WILCZAK, J.M., W.F. Dabberdt, and R.A. KROPFLI. Observations and numerical model simulations of the atmospheric boundary layer in the Santa Barbara coastal region. Journal of Applied Meteorology, 30(5):652-673 (1991). Observations of boundary-layer flow within the Santa Barbara region taken on 20 September 1985 reveal the presence of a wide variety of flow features, including mesoscale wind vortices, sea/land breezes, and thermally driven upslope/downslope winds. Details of these features, in particular the mesoscale vortices, are documented with dual-Doppler radar, Doppler sodar, aircraft, surface mesonet, and rawinsonde data. Numerical simulations of flow in the region using a mixed-layer model show good agreement with the observations. Model simulations indicate that sea-/land-roughness differences and planetary vorticity are of minor importance in forming the mid-channel eddy (MCE), an eddy that is observed in the channel during the early morning hours. MCE formation is, however, shown to be strongly dependent on the initial stratification of the atmosphere, with more intense eddies forming as the stability increases. A second independent mechanism for MCE formation appears to be the interaction of drainage flows with the large-scale flow. A daytime vortex, known as the Gaviota eddy, occurs as the result of surface heating that generates a sea-breeze flow opposing the large-scale ambient flow. WP-152 WILCZAK, J.M., and P.T. May. Radar wind profiler and RASS observations of boundary layer diurnal and seasonal variability. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, MA, 443^46 (1991). No abstract. WP-153 WOLFE, D.E., W.L. ECKLUND, D.A. CARTER, and K.S. GAGE. Evaluation of performance of NOAA's 915 MHz boundary layer radar during the 1990 Grand Canyon visibility study. Proceedings, 7th Symposium on Meteorological Observations and Instrumentation, New Orleans, LA January 13-18, 1991. American Meteorological Society, Boston, MA, 384-388 (1991). No abstract. WP-154 WUERTZ, D.B., BL. WEBER, RG. STRAUCH, and K.P. MORAN. Examining the quality of RASS temperature measurements. Extended Abstracts, Symposium on Lower Tropospheric Profiling: Needs and Technologies, Boulder, CO, September 10-13, 1991. American Meteorological Society, Boston, MA, 95-96 (1991). No abstract. WP-155 ZAMORA, RJ., B.E. MARTNER, G.P. Byrd, T.A. Niziol, and RS. Penc. Evolution of a freezing rain storm. Part I: Synoptic and mesoscale conditions. Preprints, 1st International Winter Storms Symposium, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, MA 258-263 (1991). No abstract. 183 WP-156 Zavorotnyy, V.U., and I.G. Yakushkin. Propagation of wave fields with initial Gaussian statistics through random media. Proceedings, ICO Topical Meeting on Atmospheric, Volume and Surface Scattering and Propagation, Florence, Italy, August 27-30, 1991. University of Florence, Florence, Italy, 31-34 (1991). No abstract. WP-157 Zhao, Y., R.M. HARDESTY, and M.J. POST. Use of a multi-beam transmitter for significant improvement in signal range reduction and near-range coverage for incoherent lidar systems. Proceedings, Laser Applications in Earth and Atmospheric Remote Sensing, Orlando, FL, April 1-5, 1991. Society of Photo-Optical Instrumentation Engineers, SPIE Vol. 1492, Bellingham, WA, 85-90 (1991). The enormous signal dynamic range of incoherent lidar systems is very difficult for both detectors and data acquisition systems to cope with. The high power of the near-range atmosphere-backscattered radiation may cause serious problems to detectors. If the detector can endure the high power, the dynamic range of the output electric signal still remains a problem. To solve the problems, this paper suggests using a multi-beam transmitter instead of a single-beam transmitter. With a multi-beam transmitter, a significant reduction of the signal dynamic range can always be achieved simultaneously with good near-range coverage even under different atmospheric conditions. Numerical simulations for a differential absorption lidar (DIAL) system measuring ozone in the lower troposphere below 3 km show the advantage of using a three-beam transmitter rather than a single-beam transmitter. WP-158 Zhao, Y., M.J. POST, and R.M. HARDESTY. Receiving efficiency of monostatic pulsed coherent lidars. 1: Theory. Applied Optics, 29(28):41 11-41 19 (1990). Using the theory developed in Part I, the receiving efficiency as a function of range, T)(z), is calculated under different conditions for the NOAA/ERL/Wave Propagation Laboratory C02 Doppler lidar. Theoretical analyses, numerical calculations, and experimental measurements are carried out to quantify the sensitivity of T|(z) to transmitted laser beam quality, telescope focal setting, telescope power, scanner astigmatism, LO beam divergence, and system misalignment These results bring insight to the design of practical coherent lidar systems. WP-159 Zhao, Y., M.J. POST and R.M. HARDESTY. Receiving efficiency of monostatic pulsed coherent lidars. 2: Applications. Applied Optics, 29(28):4120-4132 (1990). Using the theory developed in a previous paper, the receiving efficiency as a function of range, T)(z), has been calculated under different conditions for the NOAA/ERL/Wave Propagation Laboratory C02 Doppler lidar. Theoretical analyses, numerical calculations and experimental measurements have quantified the sensitivity of T|(z) to transmitted laser beam quality, telescope focal setting, telescope power, scanner astigmatism, LO beam divergence, and system misalignment These results bring more insight into practical design considerations of coherent lidar systems. Addendum WP-160 BEDARD, AJ., JR. Detection of avalanches using atmospheric infrasound. Proceedings, Western Snow Conference, Fort Collins, CO, April 18-20, 1989, 52-58 (1989). Long-range detection of avalanches may be feasible by analyzing low-frequency acoustic waves generated by avalanche processes. A review of recent measurements of long-range atmospheric infrasound associated with avalanche activity indicates that unique acoustic signatures are launched by avalanches, perhaps providing a means of characterizing avalanche details at distances of hundreds of kilometers. This paper reviews the process to date and indicates the form that an infrasonic avalanche detection system could take. A key conclusion is that the small explosives and equipment used for avalanche control measures could not have caused recorded infrasonic signals related to avalanche occurrences. The potential uses of a reliable detection system include avalanche forecast verification, comparisons with prediction models, and better definition of regional avalanche statistics. WP-161 BEDARD, A J., JR. A review of the evidence for strong, small-scale vortical flows during downslope windstorms. Journal of Wind Engineering and Industrial Aerodynamics, 36:97-106, Elsevier Science Publishers, Amsterdam, The Netherlands (1990). 184 During downslopc windstorms, damage can occur on quite small scales. In the foothills near Boulder, Colorado, individual trees or lines of trees may be uprooted or snapped off with little or no damage to surrounding vegetation. Also, considerable damage can occur to individual structures with no primary damage occurring nearby. Often debris will be scattered in directions different from that of the mean flow. This paper reviews evidence for the existence of vortical motions and other small-scale features associated with downslope windstorms. Possible mechanisms for producing such organized regions of small-scale vorticity are suggested. WP-162 BODHATNE, B.A., JJ. DELUISI, J.F. BOATMAN, MJ. POST, and J.M. Rosen. The Front Range lidar, aircraft, and balloon experiment. NOAA Data Report ERL CMDL-2, 27 pp. (1990). Data are presented from the Front Range Lidar, Aircraft, and Balloon (FRLAB) experiment, which was performed near Boulder, Colorado, on July 26, 1989. The purpose of this experiment was to make simultaneous measurements of aerosol profiles in the atmosphere using gTOund-based C02 and ruby lidar; airborne nephelometer, condensation nucleus (CN) counter, and aethalometer; and balloonborne backscattersonde. The data provide a unique inter-comparison between several diverse types of instruments as well as quantitatively consistent evaluation of the amount of non-Rayleigh scattering occurring in the tropospheric clean region where lidar profiles are often normalized. WP-163 CHURNSIDE, J.H., and RJ. LATAJTIS. Wander of an optical beam in the turbulent atmosphere. Applied Optics, 29(7):926-930 (1990). A simple, analytic, geometrical optics expression for the variance of the beam displacements caused by propagation through weak refractive turbulence described by the Kolmogorov spectrum is presented. The analytical formula includes the effect of the divergence or convergence of the initial beam. The formula is compared with numerical results obtained from a more complicated expression including effects of diffraction and strong path-integrated turbulence. The simple geometrical optics expression holds for apertures larger than the Fresnel zone size and larger than the ratio of the square of the Fresnel zone to the phase coherence length. WP-164 CLIFFORD, S.F., and JJJ. CHURNSIDE. Refractive turbulence and inner scale profiling using combined stellar scintillation and radar wind profilers. Proceedings, 1st European Wind Profiler Workshop, Versailles, France, March 6-8, 1989, COST 74, D59-D65 (1989). The fluctuations of spatially filtered starlight contain information about refractive turbulence strength (Cn ) at the spatial filter wavenumber. If the turbulence at different heights in tlie atmosphere is moving at different speeds, the contributions to the fluctuations from those heights will occur at different frequencies. Therefore, the C„2 profile can be inferred from the power spectrum of the fluctuations and the wind velocity profile that is determined by a radar wind profiler. Vertical resolution is expected to be in the range of several hundred meters to about a kilometer. Turbulence strength measurements to better than 50% should be easily obtainable. This technique of combining simultaneous profiler and stellar scintillation observations allows for the first time the simultaneous profiling of optical refractive turbulence, radar refractive turbulence, the inner scale of turbulence, and wind velocity. From such observations, we can determine the role of inner- scale variations in profiler backscattered intensity dropouts. WP-165 CLIFFORD, S.F., RJ. HILL, RJ. LATAJTIS, RA. Bohlander, and R.W. McMillan. Millimeter wave propagation through the turbulent atmosphere. Proceedings, International Conference on Millimeter Wave and Far-Infrared Technology, Atlanta, Georgia, June 1990. Paper Ml.l, 4 pp. (1990). An extensive set of millimeter wave propagation measurements was made during 1983 to 1985 by a team of scientists from NOAA's Wave Propagation Laboratory and Georgia Institute of Technology. Millimeter wave frequencies from 116 to 230 GHz were propagated over a 1.4 km horizontal path in Flatville, Illinois. Simultaneous, extensive measurements of the meteorology allowed a detailed comparison of the propagation characteristics with the current state of the atmosphere. We report on the observations of millimeter wave propagation characteristics in clear air. Amplitude and phase spectra for propagation in clear air are compared with theory derived using the weak refractive turbulence approximation. Excellent agreement is found when refraction fluctuations dominate over absorption fluctuations. Further, probability density functions appear to be, respectively, lognormal (amplitude) and Gaussian (phase difference). WP-166 Dabberdt, Wi\, and RM. HARDESTY. Summary of the Symposium on Lower Tropospheric Profiling: Needs and Technologies, 31 May - 3 June 1988, Boulder, CO. Bulletin of the American Meteorological Society, 71(5):665-671 (1990). No abstract. 185 WP-167 Douglas, M.W. A proposed investigation of summer precipitation over southwestern North America. Proceedings, Regional Meeting on Water Balance Studies, Ensenada, B.C. Mexico, October 18-20, 1989. Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Ensenada, B.C. Mexico, 87-97 (1989). A proposal to conduct field observations in the southwestern United States and northwestern Mexico is outlined. The observations would be made to investigate the summer season circulations that are responsible for precipitation over this region. The proposed investigation, which would be carried out during the summer of 1990, would use pilot balloon and rawinsonde observations to specify the wind field on a daily basis. A dense network of rain gauges would be established to provide verification data for precipitation estimates calculated from the upper-air wind and moisture observations on a finer scale than that provided by the basic observing network and would make observations over the northeastern Pacific. The investigation would provide data to allow a better determination of the relative contributions of diurnal forcing, synoptic-scale transient circulations, and the mean monsoonal circulation to the observed summer-season precipitation over southwestern North America. WP-168 FAIRALL, C.W. Modelling the fate and influence of marine spray. Whitecap Report No. 7, Marine Sciences Institute, University of Connecticut, Groton, CT, 15 pp. (1990). No abstract. WP-169 FATRALL, C.W., RE. Rabadi, and J.B. SNIDER Estimating integrated cloud liquid water from extended time observations of solar irradiance. Proceedings, FIRE Science Teams Workshop, Vail, CO, July 1 1-15, 1988, 301-306 (1988). No abstract. WP-170 GEORGES, T.M., R.M. JONES, and R.S. Lawrence. A PC version of the HARPO ocean acoustic ray-tracing program. NOAA TM ERL WPL-180, 18 pp. (1990). We have modified the three-dimensional ocean-acoustic ray-tracing program HARPO to run on IBM-PC-compatible computers, using the Microsoft FORTRAN Compiler, Version 4.1 or higher. PostScript and screen graphics have been added, and a floppy disk containing the complete source code is included with this report. WP-171 GEORGES, T.M., and D.R Palmer. Report on the Workshop "Applications of Ocean Acoustic Remote Sensing to Climate Monitoring," Boulder, Colorado, 7-8 June 1990. NOAA TM ERL WPL-185 (PB 105981), 8 pp. (1990). No abstract. WP-172 Gossard, E.E., RG STRAUCH, and RR. Rogers. Morphology of dropsize evolution in liquid precipitation observed by ground-based Doppler radar. Preprints, Conference on Cloud Physics, San Francisco, CA, July 23-27, 1990. American Meteorological Society, Boston, MA, 419-426 (1990). No abstract. WP-173 Gossard, E.E., D.C. WELSH, and RG. STRAUCH. Radar-measured height profiles of C„2 and turbulence dissipation rate compared with radiosonde data during October 1989 at Denver. NOAA TR ERL 442-WPL 63, 115 pp. (1990). Profiles of radar reflectivity and Doppler spectral width, for the month of October 1989, were recorded with the Stapleton 32-cm- wavelength wind profiler. The data were analyzed for hourly intervals centered on radiosonde release times, and each hour was divided into two half-hourly subperiods so that four half-hourly periods of radar data were typically analyzed for each day. The resulting profiles of the turbulence structure parameter for radar refractive index (C„2) extracted from backscattered power and of turbulence dissipation rate (actually C.2) extracted from Doppler spectral width are presented with the temperature, dew point, and refractive index profiles measured by radiosonde and plotted to the same height scale. The presence of elevated temperature inversions and humidity gradients is examined and 186 compared with radar profiler-measured quantities. A case when clouds were present is considered in some detail, because clouds are a very important source of potential false alarms in any method using radar reflectivity data to extract refractive index or humidity profiles. The experimental precautions needed to achieve the desired accuracy are discussed. WP-174 Gozani, J. Multiple-scale solutions of a wave propagating in random media. Proceedings, 1st International Conference on Computational Physics, University of Colorado, Boulder, CO, June 11-15, 1990. International Association of Mathematics and Computers in Simulation, Liege, Belgium, 20-23 (1990). This paper represents a general technique that performs partial inversion of the operator of a wide class of integro-differential equations encountered in mathematical physics. That inversion provides an alternative to the traditional selective summation technique of the iterated series that are also depicted by Feynman diagrams. WP-175 Intrieri, J.M., and L.D. OLIVIER. Life cycle of a land/sea breeze event Extended Abstract, 4th Conference on Mesoscale Processes, Boulder, CO, June 25-29, 1990. American Meteorological Society, Boston, MA, 116-117 (1990). No abstract. WP-176 KAIMAL, J.C., J.E. GAYNOR, H.A. Zimmerman, and G.A. Zimmerman. Minimizing flow distortion errors in a sonic anemometer. Boundary-Layer Meteorology, 53:103-115 (1990). This paper describes a simple approach to minimizing probe-induced flow distortion errors in a three-axis sonic anemometer. By separating the three axes, mutual interference between the transducers and supports in the three arrays is reduced. Only a transducer shadow correction determined from wind tunnel tests is needed to obtain measurements that are virtually insensitive to probe orientation relative to the mean flow. Preliminary results from a series of three atmospheric tests verify the effectiveness of this correction. WP-177 KAIMAL, J.C., and J.C. Wyngaard. The Kansas and Minnesota experiments. Boundary-Layer Meteorology, 50:31-47 (1990). Two experiments conducted almost 20 years ago have come to be regarded as important milestones in boundary-layer research. This paper recounts the motivation for those experiments, describes how they were conducted, and summarizes their results. WP-178 Larsen, S.E., J.B. Edson, P.G. Mestaycr, C.W. FAfRALL, and G. deLeeuw. Sea spray and particle deposition, air/water tunnel experiment and its relation to over-ocean conditions. Proceedings, EUROTRAC Symposium '90, Garmisch-Partenkirchen, West German, April 2-5, 1990. Academic Publishing, The Hague, The Netherlands, 71-75 (1990). No abstract. WP-179 McCoy, RJ., Jr. Frequency chirp of a hybrid Doppler lidar. Master's Thesis, Colorado State University, Fort Collins, CO, 83 pp. (1990). A hybrid Doppler lidar utilizes a pulsed infrared carbon dioxide laser as the transmitter in a laser radar system for measuring wind velocity and direction. Some of the laser light is backscattered by aerosols that are carried by the wind. The scattered light is shifted by an amount proportional to the aerosols' radial velocity. If the frequency of the transmitting laser changes throughout a pulse, the velocity estimate of the wind field is affected. The primary laser within the system is the hybrid cavity composed of two sections. The first section is a continuous-wave (cw) laser, the second is a transverse excited atmospheric pressure (TEA) laser which is basically a high-power pulsed amplifier. In the past, C02 Doppler lidars used custom-built TEA sections costing between one-quarter and one-half million dollars. The lidar being built for the Center of Geoscience at Colorado State University utilizes commercial off-the-shelf components which result in an order-of-magnitude reduction in the cost of the TEA section. The commercial TEA sections do not appear to introduce more problems than a custom-built TEA; their problems and solutions are addressed in the thesis. The TEA section is a gas laser and exhibits frequency chirping during a pulse. When the density of the gas within the TEA section changes, the frequency of the hybrid cavity radiation can also change. To minimize the uncertainty in the velocity estimate, the frequency chirp should be reduced to a minimal value and the resulting chirp must be known. Three different techniques to characterize the chirp are presented, along with methods to reduce the chirp. The chirp is measured 187 directly and parameters that affect the chirp are identified. Two of the experiments yield the chirp toward the end of the pulse where the direct measurement techniques tend to provide poor data. They also provide information on the optical quality of the cavity before, during, and after the pulse. Suggestions for modifying parameters to optimize the hybrid cavity design, thus reducing the chirp, include increased cavity length, larger mode volumes, vibrational isolation of TEA laser, and shorter pulse lengths. WP-180 Palmer, D.R., T.M. GEORGES, and R.M. JONES. Classical chaos and the sensitivity of the acoustic field to small-scale ocean structure. Proceedings, 1st International Conference on Computational Physics, University of Colorado, Boulder, CO, June 11-15, 1990. International Association of Mathematics and Computers, Liege, Belgium, 8-1 1 (1990). No abstract. WP-181 POST, MJ. Lognormal aerosol backscatter distributions: How best to average. Extended Abstract, 15th International Laser Radar Conference, Tomsk, USSR, July 23-27, 1990. Institute of Atmospheric Optics, 187-190 (1990). Statistical analysis of aerosol backscatter observed with lidars has consistently revealed lognormal distributions. It is critical to average such data correctly, particularly when a significant portion of the sample set falls below the detection threshold of the lidar. A technique is proposed for determining the geometric mean of such data in a way that is unbiased. WP-182 Priestley, J.T. An operator's manual for fluxes scintillometer software, with design recommendations for an integrated system. NOAA TM ERL WPL-178, 21 pp. (1990). A new optic -scintillation instrument for measuring the fluxes of heat and momentum in the atmospheric surface layer requires computer programs to deduce the fluxes from the measured signals. These computer programs, how to operate them, and their outputs are described. Recommendations are given for interfacing the instrument with the computer programs and for choosing appropriate averaging durations in field operation. WP-183 Ruffieux, D., and C.W. KING. The Grand Mesa Experiment: A study of drainage flow structure and evolution within an inclined basin. Preprints, 12 Internationale Tagung fue Alpine Meteorologie, Zurich, Switzerland, September 17-20, 1990. Schweizerische Meteorologische Anstalt, Zurich, 61-65 (1990). Scientists from the Wave Propagation Laboratory studied the initiation and evolution of drainage flows within a large basin located in western Colorado, using both in situ and remote sensing instruments. The paper describes the use of monostatic sodar data to classify the drainage flows according to their evolution and structure throughout the night These data provided a seasonal climatology of the drainage flows within the region for the two-year measurement period The drainage classifications are compared with the synoptic meteorology. The paper next describes the spatial variability of the initiation of the drainage. A numerical model simulating the surface energy budget for the entire region shows that the orientation of the slopes is predominant in the timing of the formation of the drainage in the basin. A local surface cooling due to an early shadowing can produce downslope winds although the major part of the basin remains under the upslope regime. WP-184 Shang, E.C., and Y.Y. Wang. Numerical simulations of the acoustic field for monitoring large-scale ocean structures. Proceedings, 1st International Conference on Computational Physics, University of Colorado, Boulder, CO, June 11-15, 1990. International Association of Mathematics and Computers in Simulation, Liege, Belgium, 24-27 (1990). No abstract. WP-185 WJLCZAK, J.M., and T.W. Christian. Case study of an orographically induced mesoscale vortex (Denver Cyclone). Monthly Weather Review, 1 18(5): 1082-1 102 (1990). Observations taken during the Convection Initiation and Downburst Experiment (CINDE) are used to describe the formation and structure of an orographically induced mesoscale vortex that frequently occurs in northeastern Colorado. This vortex, known locally as the Denver Cyclone due to its proximity to the Denver metropolitan area, is frequently associated with severe weather. We present a case study of the 188 Denver Cyclone of 25 June 1987 that formed during the late morning hours and remained nearly stationary for over 24 hours. Interesting features of the case study vortex are: low-level convergence into the center of the cyclone during nighttime hours, but divergence at the center when daytime heating becomes significant; a very shallow initial vertical extent at night, growing to nearly 1 500 m during the daytime hours; a cold pool of air on the west side of the vortex, with highest surface potential temperatures present in a warm plume on the east side; a perturbation low pressure of -150 Pa in the region of warmest potential temperatures; a sloping zone of low-level convergence, in the region of lower pressure, that triggers intense convective activity; and an upwind tilt of the center axis of the vortex. 189 APPENDIX: FEDERAL-STATE COOPERATIVE PROGRAM IN ATMOSPHERIC MODIFICATION RESEARCH AP-001 Boc, B.A., and HL. Johnson. Destabilization antecedent to a tornadic northern High Plains mesoscale convective system: A case study. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, MA, 538-541 (1990). No abstract. AP-002 Bruintjes, R.T., R. Gall, and T.L. Clark. The evolution of the flow field and cloud structures over complex terrain during a winterstorm episode. Extended Abstracts, Symposium on Lower Tropospheric Profiling: Needs and Technologies, Boulder, CO, September 10-13, 1991. American Meteorological Society, Boston, MA, 29-30 (1991). No abstract. AP-003 Bruintjes, R.T., R. Gall, TL. Clark, and WD. Hall. Comparisons between modeling and observations of precipitation over mountainous terrain in Arizona. Abstracts, IAMAP Symposium M9, Vienna, Austria, August 11-24, 1991. International Union of Geodesy and Geophysics, Brussels, Belgium, 168 (1991). No abstract. AP-004 Changnon, SA,. Great Lakes waters: Too little or too much? Supplying water and saving the environment for six billion people, EE Division/ASCE. American Society of Civil Engineers, New York, 41-49 (1990). Water supplies in the Great Lakes Basin, the world's largest fresh water supply, are more than adequate to meet current and projected needs. However, supplies could become a problem if the climate changes or water quality seriously degrades. The principal water quantity problem of the Great Lakes is the fluctuations in lake levels, providing too much or too little water. Society around the lakes has become extremely sensitive to these aberrations around average levels, one of the major lessons teamed in recent years. Recent basin-wide problems like water quality, fluctuating levels, and acid rain reveal a need for new policies and institutional approaches to the management of the Great Lakes. Lake-level forecasts are not sufficiently accurate nor long-term to allow for wise management decisions. Continuing degradation of water quality or a major climatic change during the next few decades could seriously reduce net basin supplies and create serious water supply problems. AP-005 Changnon, S.A. Impacts and some lessons taught by the 1988 drought Planning for water shortages. Proceedings, Irrigation and Drainage Division, 1989 Meeting of the ASCE, St. Louis, MO, October 15-16, 1990. American Society of Civil Engineers, New York, 263-270(1990). No abstract. AP-006 Changnon, SA. The dilemma of climatic and hydrologic forecasting for the Great Lakes. Proceedings, Symposium of the Great Lakes Water Level Forecasting and Statistics, Windsor, Ontario, May 16-17, 1991. 13-25 (1991). No abstract. AP-007 Changnon, S.A., R.R Czys, R.W. Scott, and N.E. Westcott. Illinois precipitation research: A focus on cloud and precipitation modification. Bulletin of the American Meteorological Society, 72(5):587-604 (1991). 190 At the heart of the 40-year atmospheric research endeavors of the Illinois State Water Survey have been studies to understand precipitation processes in order to learn how precipitation is modified purposefully and accidentally, and to measure the physical and socio- economic consequences of cloud and precipitation modification. Major field and laboratory activities of past years are briefly treated as a basis for describing the key findings of the past ten years. Recent studies of inadvertent and purposeful cloud and rain modification and their effects are emphasized, including a 1989 field project conducted in Illinois and key findings from an on-going exploratory experiment addressing cloud and rain modification. Results are encouraging for the use of dynamic seeding on summer cumuliform clouds of the Midwest Typical in-cloud results at -10°C reveal multiple updrafts that tend to be filled with large amounts of supercooled drizzle and raindrops. Natural ice production is vigorous, and initial concentrations are larger than expected from ice nuclei. However, natural ice production is not so vigorous as to preclude opportunities for seeding. Radar-based studies of such clouds reveal that their echo cores usually can be identified prior to desired seeding times, which is significant for the evaluation of their behavior. Cell characteristics show considerable variance under different types of meteorological conditions. Analysis of cell mergers reveals that under conditions of weak vertical shear, mid-level intercell flow at 4 km occurs as the reflectivity bridge between cells rapidly intensified. The degree of intensification of single-echo cores after they merge is strongly related to the age and vigor of the cores before they join. Hence, cloud gTOWth may be enhanced if seeding can encourage echo cores to merge at critical times. Forecasting research has developed a technique for objectively distinguishing between operational seeding and nonoperational days and for objectively predicting maximum cloud-top height and seeding suitability. An accuracy rate of up to 60% in predicting maximum echo-top-height using four categories has been achieved and suggests its use as a covariate in future experimentation. Impact studies illustrate that sizable summer rain increases would be necessary to produce economically beneficial outcomes for Corn Belt agriculture. Increases of >25% in July rainfall across certain high-production crop districts of the Com Belt would produce economic effects realized nationally. AP-008 Changnon, S.A., and H. Lambright Response. Bulletin of the American Meteorological Society, 71:1758-1759 (1990). Those who have attempted to objectively analyze most major weather modification experiments find that the typical and predictable view of federal agency leaders supervising the project is, "Yes, a few problems occurred, but the project was first rate." Staff members of the federal agency that funded and directed SCPP state that their "perceptions" of the problems in that project do not agree with certain statements in our earlier analysis. Is the cup half empty or half full? This expected bias must be factored into understanding their views. One of the key lessons we attempted to illustrate was that the sooner federal project leaders understand and admit to the real problems, the sooner there will be better designed and conducted field experiments. AP-009 Changnon, S.A., R.T. Shealy, and R.W. Scott. Precipitation changes in fall, winter, and spring caused by Sl Louis. Journal of Applied Meteorology, 30:126-134 (1990). Analysis of precipitation events in the St Louis area, based on pre-event low-level wind flow, was pursued to ascertain the presence of urban effects on fall, winter, and spring precipitation. Data from a circular, dense raingauge network were used to define quadrant (NW, NE, SE, SW) average precipitation. Winds before each event (443 events in 1971-75) were used to define the urban plume and identify which quadrant was "downwind" of the city. Results for fall revealed a 17% increase in precipitation downwind of St. Louis and a 13% increase in events with their peak rainfall occurring downwind; both outcomes were statistically significant at the 1% level. The downwind enhancement was greatest when pre-event winds were from the SE, and when average precipitation in the quadrant with the maximum value was either light (<5.1 mm) or quite heavy (>17.9 mm). The fall results agree well with earlier findings for summer rainfall that revealed a 25% increase due to enhancement in isolated airmass showers and during heavier, well-organized convective systems. Winter precipitation indicated little precipitation change downwind of St Louis. However, when SW pre-event winds existed (a flow often associated with convection), there was a statistically significant downwind increase in winter precipitation; but when pre-event winds were from SE or NW (flows frequently associated with stratiform precipitation), downwind decreases occurred. The number of spring precipitation conditions that maximized downwind of St. Louis was significantly greater than expected by chance particularly in light (<5.1 mm) events, but the total spring rainfall downwind increased only 4%. There was no suggestion of decreased precipitation in spring or fall. The urban influences to enhance precipitation appeared to be related to precipitation conditions with convective processes, and urban influences in more stratiform precipitation. AP-010 Czys, R.R. A preliminary appraisal of the natural structure and seedability of updrafts in Midwestern cumulus at the -10°C level. Journal of Weather Modification, 23:1-16 (1991). The properties of 40 updrafts in 1 1 warm-based Midwestern cumulus congestus are characterized on the basis of aircraft data collected at the -10°C level during the 1986 Precipitation Augmentation for Crops Experiment field program. Typically, clouds in this sample were found to be composed of multiple updrafts, with one updraft encountered on average for every 1.5 km of cloud penetrated. Mean updraft velocities ranged from 1 to 12 ms"1, with a sample average of 4.2 ms"'. All updrafts contained at least some supercooled liquid water content in the size range of cloud droplets (D < 50 urn). Cloud droplet liquid water content was low, typically 0.3 gm'\ and bimodal cloud droplet size distributions were occasionally observed. Most updrafts contained supercooled drizzle and raindrops. The mass of supercooled drizzle 191 and raindrops was often as large as or larger than the mass of supercooled cloud droplets, indicating an efficient coalescence process. Submillimeter-size graupel was the apparent dominant first ice form, often occurring in concentrations that exceeded those conventionally expected from ice nuclei by factors from 10 to 100. Images of vapor-grown ice crystals were not often identified in the records from 2D optical array probes. Thus it is likely that the very first ice initiated from the freezing of supercooled drizzle and raindrops. Aircraft instrumentation available to the 1986 field program was not adequate to detect ice smaller than approximately 150 um diameter. Secondary ice production (SIP) by Hallett-Mossop rine-splintering could not be verified on the basis of available information. Natural updraft buoyancies were often close to neutral, and the amount of loading by the condensate was found to have deciding influence on net buoyancy. The results of calculations suggest that buoyancy enhancements are feasible by seeding, particularly for clouds with substantial water loads and moderate updrafts. However, discerning seeding effects will be complicated by large variations in initial conditions for seeding. AP-011 Czys, R.R., and M.S. Petersen. A least-squares polynomial technique for discriminating between drops and graupel in 2D image records. Preprints, 7th Symposium on Meteorological Observations and Instrumentation, New Orleans, LA, January 13-18, 1991. American Meteorological Society, Boston, MA, J51-J55 (1991). No abstract. AP-012 Demoz, B.B., J.A. Warburton, and RJL Stone. The influence of riming on the oxygen isotopic composition of ice-phase precipitation. Atmospheric Research, (1991). The oxygen isotopic composition of freshly fallen snow has been measured simultaneously with ice-crystal photography at a high altitude station in the central Sierra Nevada. These and other meso- and micro-scale cloud measurements have been used to study the short-term 6lsO variations of ice-phase precipitation from winter storms. In this study, snow samples collected from six storm events in 1985 were used. The results show that- (1) the degree of riming and the 8'80 value of the ice particles correlate positively for six of the six storms sampled, except at times of strong convective activity; (2) temperatures of ice phase initiation do not agree with the isotopically derived "temperatures" of the precipitation reaching the ground, as a result of riming; hence, the amount and location of supercooled liquid water in the clouds are considered to be strong determining factors influencing the 6lsO values; and (3) no obvious correlations were observed between precipitation rate and 5180 or between the maximum precipitation intensity and the range of the 6180 values of the snowfall. AP-013 Detwiler, A.G., J.H. Helsdon, Jr., and D.J. Musil. Evolution of a band of severe storms. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, MA, 705-709 (1990). No abstract. AP-014 Finnegan, W.G., and Rl. Pitter. Chemical reactions in growing snowflakes. Poster presentation, Annual Meeting of the AAAS, Washington, DC, February 14-19, 1991. American Association for the Advancement of Science, Washington, DC, (1991). No abstract. AP-015 Finnegan, W.G., and Rl. Pitter. Comments on "The persistence of seeding effecis in a winter orographic cloud seeded with silver iodide burned in acetone." Journal of Applied Meteorology, 30:903-904 (1991). Article by Deshler and Reynolds (1990) contains errors and misconceptions concerning the chemistry, generation, characterization, and functioning mechanisms of silver iodide-containing ice nucleus aerosols. These errors may be due in part either to the authors not understanding the processes of ice nucleation and ice crystal formation, which are critical aspects of cold cloud modification, or to their careless use of jargon. In this Comment, only the errors in Deshler and Reynolds (1990) relevant to ice formation are discussed. AP-016 Finnegan, W.G., RL. Pitter, and L.G. Young. Preliminary study of coupled oxidation-reduction reactions of included ions in growing ice crystals. Atmospheric Environment, 25A:2531-2535 (1991). 192 Cloud chamber studies have demonstrated coupled oxidation-reduction reactions of included ions in free-falling ice crystals growing in a supercooled liquid water cloud. These reactions are hypothesized to occur as a consequence of preferential ion separations which take place at the interface between growing ice and the liquid layer at the growing crystal surfaces, followed by electron transfers to establish system neutrality. Oxidations of sulfide ion to sulfate ion and of halide ions to higher valence species have been documented. Reductions of silver ion to metallic silver and of sulfate ion to lower valence species have also been documented in systems of appropriate ion compositions. Similar reactions have been reported to occur during the freezing of bulk dilute solutions of ammonium and/or halide salts. AP-017 Hall, W.D., D. Matthews, and A. Super. Orographic production of supercooled liquid water and precipitation over the Mogollon Rim of Arizona. Preprints, Conference on Cloud Physics, San Francisco, CA, July 23-27, 1990. American Meteorological Society, Boston, MA, 754-757 (1990). No abstract. AP-018 Heimbach, J.A., Jr. Interim data inventory for 1991 flight operations in support of Utah/NOAA Cooperative Atmospheric Modification Research Program. Department of Natural Resources, State of Utah, Salt Lake City, UT, 59 pp. (1991). No abstract. AP-019 Helsdon, J.H., Jr. Analysis of a high positive flash frequency severe storm (June 28, 1989) from the North Dakota Thunderstorm Project Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, MA, 744-747 (1990). No abstract. AP-020 Hollinger, SJE., and S A. Changnon. Response of com yield components to simulated precipitation augmentation. Preprints, Conference on Agriculture and Forest Meteorology, Salt Lake City, UT, September 10-13, 1991. American Meteorological Society, Boston, MA, 17- 20(1991). No abstract. AP-021 Huggins, A.W., and A.B. Long. Investigations of a winter mountain storm in Utah. Part HI: Single-Doppler radar measurements of turbulence. Journal of the Atmospheric Sciences, 48:1306-1318 (1991). This Part m of a multipart paper deals with the analysis of turbulent morion in a winter storm, which occurred over the mountains of southwest Utah. The storm was documented with a long duration single Doppler radar data set (~21 h) comprised of volume scan observations acquired at 10-min intervals. Turbulence parameters were determined using a new technique of volume processing of single Doppler radar data. Physical analysis of turbulence is restricted to three particular storm regions: a prefrontal region far removed from a cold frontal discontinuity, a frontal zone aloft, and a low layer in the post-frontal region where a long lasting (~6 h) wind-maximum existed. The prefrontal period showed enhancement of turbulent parameters near 2.6 km height, apparently due to disturbed flow caused by an upwind mountain range. Turbulence parameters in this prefrontal region showed good agreement with K-mixing length theory. Within the frontal zone, most turbulence parameters reached peak values, but were generally less than orographically induced turbulence values in the prefrontal period. Turbulence in the low-level postfrontal period experienced periodic oscillations consistent with precipitation and kinematic variables described in Parts I and H, and associated with mesoscale precipitation bands. Acceleration of the valley-parallel wind component was apparent in prefrontal and postfrontal periods and was related to the specific valley configuration through a Venturi effect AP-022 Huston, M.W. One- and two-dimensional model results compared with observations from a North Dakota cloud. Master's Thesis, Department of Meteorology, South Dakota School of Mines & Technology, Rapid City, SD, 97 pp. (1991). No abstract. 193 AP-023 Johnson, L.R., and PI. Smith. Estimation of convectivc rain volumes utilizing the area-time-integral technique. Preprints, 8th Conference on Hydrometeorology, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, MA, 165-168 (1990). No abstract. AP-024 Kennedy, P.C., N.E. Westcott, and R.W. Scott. Single Doppler radar observations of a mini-tornado. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, MA, 209-212(1990). No abstract. AP-025 Klimowski, B.A., and JX). Marwitz. Single Doppler analyses of a severe squall line and gust front. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, MA, 252-255(1990). No abstract. AP-026 Kopp, F.J., and H.D. Orville. The use of a cloud model to predict convective and stratiform clouds and precipitation. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, MA, 322-327 (1990). No abstract. AP-027 Kunkel, K.E., S.E. Hollinger, and F. Kogan. Soil moisture/evaporation/precipitation feedback. A case study of the 1988 drought Proceedings, 10th Conference on Biometeorology and Aerobiometeorology (Special Session on Hydrometeorology), Salt Lake City, UT, September 10-13, 1991. American Meteorological Society, Boston, MA, J42-J45 (1991). No abstract. AP-028 Long, A.B., and A.W. Huggins. A method of retrieving turbulence parameters from volume processing of single-DoppIer radar measurements. Journal of Atmospheric and Oceanic Technology, 8:491-505 (1991). In previous work the derivation of turbulence parameters from single-Doppler radar observations was performed with data acquired along a horizontal circle. Here the technique is extended to all the radar data within a horizontal cylindrical slice of finite depth using the same basic assumptions of linearity of the mean wind field and horizontal homogeneity of the turbulence. The method allows the extraction of the six Reynolds stress components, together with their vertical derivatives, and the turbulent fluxes of a scalar quantity deduced from the reflectivity data. Experimental data were used for the performance evaluation of the methodology. A simple testing procedure was carried out to remove erroneous results. The statistical uncertainty in the measured Reynolds stress terms was found to be about 0.05 m2s'2, except for the variance of the vertical component, which was poorly retrieved because of an absence of data at high elevation angles. Calculations showed that contamination of the vertical momentum flux measurements by the scatterer fall speed was negligible. An analysis of the response function of the technique to the atmospheric scales tended to show that the diameter of the processing slices corresponded to the largest turbulent scale dimension involved in the measured turbulence quantities. AP-029 Meitin, R.J., and RA. BROWN. A dual-Doppler analysis of North Dakota thunderstorms using airborne and ground-based radars. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, MA, 225-230 (1990). No abstract. 194 AP-030 Meitin, RJ., RA. BROWN, and J.G. MElllN. Comparison of airborne dual-Doppler and airbome/ground-based dual-Doppler analyses of North Dakota thunderstorms. Preprints, 25th International Conference on Radar Meteorology, Paris, France, June 24-28, 1991. American Meteorological Society, Boston, MA, 474-477 (1991). No abstract. AP-031 Mitchell, DL Evolution of snow-size spectra in cyclonic storms. Part II: Deviations from the exponential form. Journal of the Atmospheric Sciences, 48:1885-1889 (1991). Using a form of the stochastic collection equation, conservation equations for the first and second moments of the mass were parameterized to yield a height dependent one-dimensional snow growth model for unrimed stratiform snowfall. Snow-size distributions were represented by the form N(D) = N„D* exp(-AD), and solutions for X and N„ were obtained. The spectral parameter v allows the concentration of the smaller ice particles to deviate from the exponential form and controls the degree of subexponential or superexponential behavior. The sub- and superexponential spectra analyzed in this study had v values of 1 and -1, respectively. A number of simple analytical relationships was developed that describes various properties of size distributions, regardless of the particle type involved. A method was developed for obtaining the three parameters of the size distribution used in the model from measured size distributions. In addition, an expression was derived to relate the two X of an exponentially parameterized and a nonexponentially parameterized size distribution. The effect of sub- and superexponential spectra on the evolution of snow-size spectra by vapor diffusion and aggregation was examined using a steady state, fixed snowfall rate profile. Diffusional growth rates of individual ice crystals (no aggregates) were relatively low when the size distribution was constrained to be superexponential in form. This resulted in steeper spectra (smaller crystal sizes) and higher ice-crystal number concentrations. Aggregation was the only growth process that substantially increased ice particle sizes for superexponential spectra, while both vapor diffusion (in the upper cloud) and aggregation (in the mid-to-lower cloud) contributed substantially to size increases for subexponential spectra. An expression for the aggregation efficiency was formulated. The primary factors governing aggregation appear to be the aggregation efficiency, the ice particle number concentration, and the mean diameter. The expression may be useful in larger numerical cloud models. Mean aggregation rate constants were determined for sub- and superexponential spectra, and for exponential spectra. The mean aggregation rate constant for superexponential spectra was approximately 50% greater than for subexponential spectra. Finally, it was found that the degree of subexponential behavior predicted when v = 1 was consistent with that observed in various levels in stratiform clouds. However, better measurements are needed to substantiate this finding. AP-032 Mitchell, DL, and R.D. Borys. A field instrument for examining in-cloud scavenging mechanisms by snow. Proceedings, 5th International Conference on Precipitation Scavenging and Atmosphere-Surface Exchange Processes, [Award-winning Poster], Richland, WA, July 15-19, 1991. Electric Power Research Institute, U.S. Department of Energy, U.S. Environmental Protection Agency, NOAA (1991). No abstract. AP-033 Musil, D.J., PJ. Smith, and N.E. Westcott Armored aircraft observations of a severe hailstorm in Illinois. Preprints, 16th Conference on Severe Local Storms, Kananaskis Provincial Park, Alberta, Canada, October 22-26, 1990. American Meteorological Society, Boston, MA, 485-488 (1990). No abstract. AP-034 Nair, U.S. Modeling and observational study of the June 28, 1989, case from the North Dakota Thunderstorm Project Master's Thesis, Department of Meteorology, South Dakota School of Mines and Technology, Rapid City, SD, 153 pp. (1991). No abstract. AP-035 Petersen, M.S., K.JE. Kunkel, and PJ. Lamb. Implementation of a semi-physical model for examining solar radiation in the MidwesL Preprints, 7th Conference on Applied Climatology, Salt Lake City, UT, September 10-13, 1991. American Meteorological Society, Boston, MA 81-84 (1991). No abstract. 195 AP-036 Pitter, RX., and W.G. Finnegan. A mechanism for ice crystal symmetry and for processes of ice crystal growth and interaction. Poster presentation. Annual Meeting of the AAAS, Washington, DC, February 14-19, 1991. American Association for the Advancement of Science, Washington, DC, (1991). No abstract. AP-037 Pitter, Ri., and W.G. Finnegan. Implications of the separation of ions in growing ice crystals. Abstracts, IAMAP Symposia, Vienna, Austria, August 1 1-24, 1991. International Union of Geodesy and Geophysics, Brussels, Belgium, (1991). No abstract. AP-038 Pitter, RL., and R. Zhang. Numerical simulation of the scavenging rates of ice crystals of various microphysical characteristics. Advances in Atmospheric Science, 8:175-200 (1991). Numerical models of trajectories of small aerosol spheres relative to oblate spheroids were used to determine ice crystal scavenging efficiencies. The models included the effects of aerodynamic flow about the ice particle, gravity, aerosol particle inertia, and drag and electrostatic effects. Two electric configurations of the ice particle were investigated in detail. The first applied a net charge to the ice particle, of magnitude equal to the mean thunderstorm charge distribution, while the second applied a charge distribution, with no net charge, to the ice particle to model the electric multipole charge distribution. The results show that growing ice crystals with electric multipoles are better scavengers than single ice crystals with net thunderstorm charges, especially in the Greenfield gap (0.1 to 1.0 urn), and that larger single crystals are better scavengers than smaller single crystals. The results also show that the low density ice crystals are more effective scavengers with net charges than they are with charge distribution. AP-039 Priegnitz, DL. The interactive radar analysis software (IRAS) package. Preprints, 7th International Conference on Interactive Information Processing Systems, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, MA, 173-176 (1991). No abstract. AP-040 REINKING, R-F., RJ. Meitfn, F. Kopp, and HD. Orville. Fields of motion and transport within a sheared thunderstorm. Preprints, 2nd International Meeting on Agriculture and Weather Modification, Zamora, Spain, March 12-15, 1991. International Committee on Agriculture and Atmospheric Modification, Zamora, Spain, 59-66 (1991). No abstract. AP-041 Riebsame, WJE., S.A. Changnon, T.R. Karl. Drought and Natural Resources Management in the United States. Westview Press, Boulder, CO, 174 p. (1991). The 1987-89 drought was a signal event in the evolving inter-relationships among climate, natural resources management, technology, and society in the United States. Over half of the country experienced severe to extreme drought by midsummer of 1988. Losses upward to $39 billion illustrate the continuing, perhaps growing, vulnerability of many natural resources and economic sectors to drought and other climate fluctuations in the U.S. Despite decades of crop breeding, water system development, and other improvements in climate-sensitive technologies like cloud seeding, the drought demonstrated that the simple lack of "normal" rainfall still provokes serious disruptions in agriculture, water supply, transportation, environmental quality, and other areas. It can affect the health and well-being of millions of people and evoke billions of dollars in government aid. The drought did evoke some successful responses, and lessons from past droughts were profitably applied in some cases. No rapid adoption of weather modification occurred, a condition different than in past major droughts of 1950-1985. Indeed, the successful responses in 1988-89 indicate a greater potential for reducing drought impacts than was observed, especially during the height of the drought in 1988. By diagnosing this case, and placing it in the context of the evolving relationship between climate and society, we seek to point the way toward improved drought management in the future, as well as to better illuminate the path to reduced overall climate vulnerability. 196 AP-042 Sassen, K. The lidar depolarization technique for cloud and aerosol research. Preprints, 71st Annual Meeting of the American Meteorological Society, New Orleans, LA, January 14-18, 1991. American Meteorological Society, Boston, MA, 448-451 (1991). No abstract. AP-043 Sassen, K. The polarization lidar technique for cloud research: A review and current assessment Bulletin of Jhe American Meteorological Society, 72, (1991). The development of the polarization lidar field over the past two decades is reviewed, and the current cloud research capabilities and limitations are evaluated. Relying on fundamental scattering principles governing the interaction of polarized laser light with distinctly shaped hydrometers, this remote sensing technique has contributed to our knowledge of the composition and structure of a variety of cloud types. For example, polarization lidar is a key component of current climate research programs to characterize the properties of cirrus clouds, and is an integral part of multiple remote sensor studies of mixed-phase cloud systems, such as winter mountain storms. Although unambiguous cloud phase discrimination and the identification of some ice particle types and orientations are demonstrated capabilities, recent theoretical approaches involving ice crystal ray-tracing and cloud microphysical model simulations are promising to increase the utility of the technique. New results simulating the single and multiple scattering properties of precipitating mixed-phase clouds are given for illustration of such methods. AP-044 Sassen, K., H. Zhao, and G.C. Dodd. Simulated polarization diversity lidar returns from water and precipitating mixed phase clouds. Applied Optics, 30, (1991). The dependence of polarization lidar returns on basic microphysical and thermodynamic variables is assessed using a cloud model to simulate the growth of water and mixed (water and ice) phase clouds. Cloud contents that evolve with height in updrafts are converted using Mie theory into cloud droplet single and double backscattering, and attenuation coefficients. The lidar equation includes forward multiple scattering attenuation corrections based on diffraction theory for droplets and ice crystals, whose relative scattering contributions are treated empirically. Lidar depolarization is computed from droplet and crystal single scattering, and an analytical treatment of droplet double scattering. Water cloud results reveal the expected increases in linear depolarization ratios (6) with increasing lidar field-of-view and distance-to-cloud, but also show that depolarization is a function of cloud liquid water content which depends primarily on temperature. Ice crystals modulate mixed-phase cloud liquid water contents through water vapor competition effects, thereby affecting multiple scattering 6 values as functions of temperature, and crystal size and concentration. Although minimum 5 at cloud base increase with increasing ice content, the peak measurable 6 in the cloud decrease. Comparison with field data demonstrate that this modeling approach is a valuable supplement to cloud measurements. AP-045 Smith, PX, H.D. Orville, and BA. Boe. An overview of the 1989 North Dakota Thunderstorm Project Preprints, 2nd Yugoslav Conference on Weather Modification, Volume L Mavrovo, Yugoslavia, April 2-4, 1991. Republic Hydrometeorology Institute of SR, Macedonia, Skopje, Yugoslavia, 16-24 (1991). No abstract. AP-046 Smith, PJL, H.D. Orville, B A. Boe, and JX. Stith. Weather modification in the Dakotas. Preprints, 2nd International Meeting on Agriculture and Weather Modification, Zamora, Spain, March 12-15, 1991. International Committee on Agriculture and Atmospheric Modification, Zamora, Spain, 71-82 (1991). No abs'ract. AP-047 Stith, JX. Observations of cloud top entrainment using gaseous tracer techniques. Preprints, Conference on Cloud Physics, San Francisco, CA, July 23-27, 1990. American Meteorological Society, Boston, MA, 532-535 (1990). No abstract. 197 AP-048 Warburton, J., and R Stone. The chemistry of snow in the central Sierra Nevada: A study of snowfall over a 20-year period, 1966- 1985. I. Changes in pH. Journal of Atmospheric Research, 25:377-384 (1990). Fresh snowfall precipitation has been collected at 14 sites in the central Sierra Nevada during the winter seasons from 1966 to 1985. The pH of these 1,398 individual snow samples has been measured throughout this 20-year period. The results indicate that there has been a small increase in acidity of 0.02 pH units per year in this region over this 20-year period. The pH has changed from approximately 5.6 in 1966 to 5.2 in 1985. In the period from 1972 to 1974, the pH changed more dramatically from 5.2 to 4.6, but returned to 5.4 again in 1975- 76. The cause of such an increase in acidity in this period is not known, but it was coincidental with the world energy crisis when larger quantities of high lead and sulfur content fossil fuels were in use in the United States. AP-049 Warburton, J.A., R.H. Stone, and L.G. Young. Assessment of seeding effects by chemical methods. Preprints, 2nd International Meeting on Agriculture and Weather Modification, Zamora, Spain, March 12-15, 1991. International Committee on Agriculture and Atmospheric Modification, Zamora, Spain, 41-44 (1991). No abstract. AP-050 Warburton, J.A., and MA. Wetzel. The liquid water and tee content in winter storms in relation to precipitation augmentation potential. Preprints, 2nd International Meeting on Agriculture and Weather Modification, Zamora, Spain, March 12-15, 1991. International Committee on Agriculture and Atmospheric Modification, Zamora, Spain, 37-40 (1991). No abstract. AP-051 Westcott, N.E. The bridging and growth of aggregating echo cores. Preprints, Radar Meteorology Conference, American Meteorological Society, Boston, MA, 424-427 (1991). No abstract. AP-052 Zhang, S. Two-dimensional model transport simulation in clouds compared with observations. Master's Thesis, Department of Meteorology, South Dakota School of Mines and Technology, Rapid City, SD, 75 pp. (1991). No abstract. AP-053 Zhang, R., RX. Pitter, and W. Weng. A numerical simulation of aerosol scavenging by solid precipitation. Proceedings, 5th International Conference on Precipitation Scavenging and Atmosphere-Surface Exchange Processes, Richland, WA, July 15-19, 1991. Electric Power Research Institute, U.S. Department of Energy, U.S. Environmental Protection Agency, NOAA (1991). No abstract. 19X ABOUT THE AUTHOR INDEX All authors of all publications are listed. An asterisk indicates a first author. ERL authors' names are typed in all capital letters. The words "et al." indicate that a publication had more than one author. The alphanumeric code following an author's name gives the location of the bibliographic entry. Example: WP-061 is the sixty-first entry in the Wave Propagation Laboratory section. Following are the codes used, their meanings, and inclusive pages: Code Laboratory or Publishing Group Pages AL Aeronomy Laboratory 1-14 AO Atlantic Oceanographic and Meteorological Laboratory 45-62 AP Appendix: Federal-State Cooperative Program in Atmospheric Modification Research 190-198 AR Air Resources Laboratory 15-44 CM Climate Monitoring and Diagnostics Laboratory 63-74 FS Forecast Systems Laboratory 75-82 GF Geophysical Fluid Dynamics Laboratory 83-94 GL Great Lakes Environmental Research Laboratory 95-105 NS National Severe Storms Laboratory 106-124 PM Pacific Marine Environmental Laboratory 125-139 SE Space Environment Laboratory 140-155 WP Wave Propagation Laboratory 156-189 200 AUTHOR INDEX AAGAARD, K., et al., PM-001 AAGAARD, K., et al., PM-047 *ABERSON, S.D., et al., AO-001 Abrevaya, A., et al., NS-034 ABSHIRE, N.L., et al., FS-049 ABSHIRE, N.L., et al., WP-095 ABSHIRE, N.L., et al., WP-142 ♦ACKERMANN, G.R., AR-002 ACKLEY, M.H., et al., FS-049 ACKLEY, M.H., et al., WP-142 ♦ALBERS, S.C., FS-001 ALBERS, S.C., et al., FS-025 ALBERS, S.C., et al., FS-026 ALBERS, S.C., et al., FS-027 ALBERS, S.C., et al., FS-039 ALBERS, S., et al., FS-019 Albrecht, B.A., et al., WP-111 ♦ALBRITTON, D.L., et al., AL-001 ALBRITTON, D.L., et al., AR-053 *Alkezweeny, A., et al., AR-001 ♦Alldredge, A.L., et al., WP-OOl ♦Allwine, K.J., et al., AR-128 Alquist, N.C., et al., CM-003 Alvarez, J.M., et al, WP-125 Anderson, D.E., Jr., et al., AL-030 Anderson, J.G., et al., AL-005 Anderson, J., et al., AR-113 Anderson, L.C., et al., AL-030 ♦Andreas, E.L., et al., CM-001 *ANGELL, J.K., AR-003 *ANGELL, J.K., AR-129 ANGELL, J.K., et al., AR-038 ANGELL, J.K.. et al., AR-039 ♦Angevine, W.M., et al., AL-002 ♦Angevine, W.M., et al., AL-003 ♦Arlander, D.W., et al., PM-068 Arnold, M., et al., GF-001 ARTZ, R.S., et al., AO-029 ARTZ, R.S., et al., AO-060 ARTZ, R.S., et al., AO-065 ARTZ, R.S., et al., AR-048 ARTZ, R.S., et al., AR-052 ARTZ, R.S., et al., AR-088 ARTZ, R.S., et al., AR-095 ARTZ, R.S., et al., AR-103 ARTZ, R.S., et al., AR- 117 ARTZ, R.S., et al., CM-047 Arya, S.P., et al., AR-057 ♦ASSEL, R.A, GL-001 *ASSEL, R.A, GL-002 *ASSEL, R.A., et al., GL-003 *ASSEL, R.A., et al.. GL-004 Atlas, D., et al., AO-045 ATWOOD, D.K., et al., PM-063 *AUBLE, D.L., et al., AR-004 AUBLE, D.L., et al., AR-083 ♦AUGUSTINE, J.A., et al., NS-001 AUGUSTINE, J.A., et al., NS-052 AUGUSTINE, J.A., et al., NS-085 AUGUSTINE, J.A., et al., WP-078 Avery, S.K., et al., AL-010 Avery, S.K., et al., AL-019 Aydin, K., et al., NS-002 Aydin, K., et al.. NS-102 ♦Bahar, E., WP-002 ♦Bahar, E., WP-003 *Bahar, E., WP-004 * Bahar, E., WP-005 Baig, S.R., et al., AO-048 *Baik, J.-J., et al., AO-002 Bailey, K.M., et al., PM-032 BAKER, C.B., et al., AR-023 BAKER, C.B., et al., AR-024 BAKER, C.B., et al.. AR-046 BAKER, C.B., et al., AR-075 ♦BAKER, C.B., et al., AR-130 BAKER, C.B., et al., WP-047 Baker, D.J., et al., PM-047 ♦Baker, D.N., et al., SE-001 BAKER, E.T., et al., PM-009 BAKER, E.T., et al., PM-015 ♦Baker, J.E., et al., GL-005 ♦Balakrishnan, N., et al., NS-002 Balakrishnan, N., et al., NS-O10 Balakrishnan, N., et al., NS-015 Balakrishnan, N., et al., NS-101 Balakrishnan, N., et al., NS-102 ♦BALCH, C.C., SE-002 ♦BALCH, C.C., SE-003 ♦BALDOCCHI, D.D., et al., AR-005 ♦BALDOCCHI, D.D., et al, AR-006 ♦BALDOCCHI, D.D., et al, AR-007 BALDOCCHI, D.D., et al., AR-076 BALDOCCHI, D.D., et al„ AR-121 Baldridge, K.A., et al., AR-074 Ballentine, R., et al., WP-114 ♦Balsley, B.B., et al., AL-004 Balsley, B.B., et al., AL-010 Balsley, B.B., et al., AL-014 Balsley, B.B., et al., AL-015 Balsley, B.B., et al.. AL-018 Balsley, B.B., et al., AL-019 Balsley, B.B., et al., AL-021 Balsley, B.B., et al., AL-022 ♦Banjanin, Z.B., et al., NS-003 ♦BANTA, R.M., et al., WP-006 ♦BANTA, R.M., et al., WP-007 ♦BANTA, R.M., et al., WP-008 BANTA, R.M., et al., WP-048 BANTA, R.M., et al., WP-058 BANTA, R.M., et al., WP-102 BANTA, R.M., et al., WP-103 Barber, W.E., et al., PM-058 Barbetti, m., et al., CM-007 ♦Barchet, W.R., et al., AR-008 Barchet, W.R., et al., AR-029 201 •Bard, E., et al., GF-001 ♦Bardwell, C.A.. et al., AR-009 Bardwell, C.A., et al., AR-012 ♦Barnes, G.M., et al., AO-003 ♦Barnes, G.M., et al., AO-004 BARNES, S.L., et al., FS-013 BARNES, S.L., et al., NS-022 Bamett, T., et al., AR-043 ♦Barrow, C.H., et al., SE-004 Barry, R.G., et al., CM-001 ♦BARTELS, D.L., et al., NS-004 ♦BARTELS, D.L, et al., NS-005 Barth, M.C., et al., FS-049 BARTH, M.F., et al., WP-142 Bartlo, J. A., et al., AO-008 ♦Bastian, T.S., et al., SE-O05 ♦BATES, JJ., CM-002 BATES, T.S., et al., AR-053 BATES, T.S., et al., PM-065 ♦BATES, T.S., et al., PM-069 Baugues, K.A., et al., AR-074 Baumgartner, D.J., et al., PM-019 Baxter, C, et al., PM-016 ♦BEDARD, A.J., JR., WP-009 ♦BEDARD, A.J., JR., WP-160 ♦BEDARD, A.J.. JR., WP-161 ♦BEDARD, A.J., JR., et al., WP-010 BEDARD, A.J., JR., et al., WP-101 Bedford, C, et al., WP-114 BEELER, R.H., et al., WP-133 ♦BEETON, A.M., GL-006 ♦BEETON, A.M., GL-007 ♦BEETON, A.M., et al., GL-008 BEETON, A.M., et al., GL-034 Bender, LW., et al., AR-120 BENDER, M.A., et al., GF-017 ♦BENJAMIN, S.G., FS-002 ♦BENJAMIN, S.G., et al., FS-003 ♦BENJAMIN, S.G., et al., FS-004 ♦BENJAMIN, S.G., et al., FS-005 BENJAMIN, S.G., et al., FS-033 BENJAMIN, S.G., et al., FS-041 BENJAMIN, S.G., et al., FS-042 Benz, A.O., et al., SE-054 BERBERIAN, G.A., et al., AO-023 ♦BERNARD, E.N., PM-002 ♦BERNARD, E.N., PM-003 ♦BERNARD, E.N., PM-004 BERNARD, E.N., et al., PM-022 ♦Beryulev, G.P., et al., AO-005 Betzer, P.R., et al., PM-066 BEZDEK, H.F., et al., AO-050 ♦BINKOWSKI, F.S., et al., AR-010 ♦BINKOWSKI, F.S., et al., AR-011 BINKOWSKI, F.S., et al., AR-016 BINKOWSKI, F.S., et al., AR-017 BINKOWSKI, F.S., et al., AR-030 BINKOWSKI, F.S., et al., AR-115 BINKOWSKI, F.S., et al., AR-124 Bird, T, et al., CM-007 ♦BIRKENHEUER, D., FS-006 ♦BLACK, M.L., et al., AO-006 BLACK, M.L., et al., AO-064 BLACK, P.G., et al., AO-005 ♦BLACK, P.G., et al., AO-007 BLACK, P.G., et al., AO-010 BLACK, P.G., et al., AO-062 BLACK, P.G., et al., AO-063 BLACK, P.G., etal., AO-071 BLACK, P.G., et al., AO-080 BLANCHARD, D.O., et al., NS-064 Block, D.R., et al., AR-025 Blood, D.M., et al., PM-037 ♦Bluestein, H.B., et al., NS-006 Bluestein, H.B., et al., NS-047 BOATMAN, J.F., et al., AO-025 BOATMAN, J.F., et al., AO-039 BOATMAN, J.F., et al., AO-065 BOATMAN, J.F., et al., AR-009 ♦BOATMAN, J.F., et al., AR-012 BOATMAN, J.F., et al., AR-044 BOATMAN, J.F., et al., AR-047 BOATMAN, J.F., et al., AR-060 BOATMAN, J.F., et al., AR-061 BOATMAN, J.F., et al., AR-062 BOATMAN, J.F., et al., AR-063 BOATMAN, J.F., et al., AR-064 BOATMAN, J.F., et al., AR-065 BOATMAN, J.F., et al., AR-069 BOATMAN, J.F., et al.. AR-095 BOATMAN, J.F., et al., AR-101 BOATMAN, J.F., et al., AR-107 BOATMAN, J.F., et al., AR-109 BOATMAN, J.F., et al., CM-004 BOATMAN, J.F., et al., WP-011 BOATMAN, J.F., et al., WP-162 Bochang, X., et al., PM-067 Bodeen, C.A., et al., PM-019 ♦BODHAINE, B.A., et al., CM-003 ♦BODHAINE, B.A., et al., CM-004 ♦BODHAINE, B.A., et al., WP-011 ♦BODHAINE, B.A., et al., WP-162 ♦Boe, B.A., et al., AP-001 Boe, B.A., et al., AP-045 Boe, B.A., et al., AP-046 ♦BOGRAD, S.J., PM-005 Bohlander, R.A., et al., WP-165 ♦BOND, N.A., et al., PM-006 BOND, N.A., et al., PM-038 ♦BOND, N.A., et al., WP-012 Bonnel, B., et al., GF-009 Boone, P.F., et al., AR-120 Bopegedera, A.M.R.P., et al, AL-044 Borek, J.W., et al., AR-057 BORG-BREEN, D., et al., PM-070 ♦BORNMANN, P.L., SE-006 ♦BORNMANN, P.L., SE-007 ♦BORNMANN. P.L., et al., SE-008 BORNMANN, P.L, et al., SE-068 Borys, R.D., et al., AP-032 ♦Bosart, L.F., et al., AO-008 Bouwer, S.D., et al., SE-048 ♦Bowdle, D.A., et al., WP-013 ♦Bowdle, D.A., et al., WP-014 Bowne, N.E., etal., AR-018 Bradley, R.S., et al., CM-015 202 Bradshaaw, G., et al., AR-059 ♦BRANDES, E.A., NS-007 BRANDES, E.A., et al., NS-006 *BRANDES, E.A., et al., NS-008 ♦BRANDES, E.A., et al., NS-009 ♦BRATKOVICH, A.W., GL-009 BRATKOVICH, A.W., et al., GL-018 Brecht, S.H., et al., SE-055 ♦Bretherton, F.P., et al., GF-002 Brewster, K.A., et al., FS-003 *BRIGGS, G.A., et al., AR-013 Bringi, V.N., et al., NS-002 *Bringi, V.N., et al., NS-010 Bringi, V.N., et al., NS-015 Bringi, V.N., et al., NS-102 ♦BROCCOLI, A.J., et al., GF-003 Brock, F., et al., NS-035 Brown, C.J., et al., AO-066 Brown, D.W., et al., WP-013 Brown, J.C, et al., SE-068 ♦BROWN, R.A., NS-01 1 BROWN, R.A., et al., AP-029 BROWN, R.A., et al., AP-030 ♦BROWN, R.A., et al., NS-012 BROWN, R.A., et al., NS-065 BROWN, R.A., et al., NS-066 BROWN, R.A., et al., NS-098 BROWN, R.A., et al., WP-087 BROWN, R.A., et al., WP-088 ♦Bruintjes, R.T., et al., AP-002 ♦Bruintjes, R.T., et al., AP-003 Brummer, R., et al., FS-003 BRUNDAGE, J.M., et al., FS-038 Brune, W. H., et al., AL-030 ♦Brune, W.H., et al., AL-005 BRYAN, K., et al., GF-002 ♦BRYAN, K., et al., GF-004 Buckley, B., et al., CM-007 Buhr, M.P., et al., AL-017 Buhr, M.P., et al., AL-047 Buhr, M.P., et al., AL-057 Bullas, J., etal., FS-031 ♦BULLOCK, C.S., et al., FS-007 ♦BULLOCK, C.S., et al., FS-008 ♦BULLOCK, O.R., Jr., AR-014 Bundy, D., et al., AR-123 ♦BURGESS, D.W., et al., NS-013 BURGESS, D.W., et al., NS-017 ♦Burkhart, G.R., et al., SE-009 ♦Burkhart, G.R., et al., SE-010 ♦Burkhart, G.R., et al., SE-Oll Burkhart, G.R., et al., SE-014 ♦Burkholder, J.B., et al., AL-006 Burkholder, J.B., et al., AL-025 Burkholder, J.B., et al., AL-033 Burkholder, J.B., et al., AL-043 Burkholder, J.B., et al., AL-044 Burkholder, J.B., et al., AL-045 Burkholder, J.B., et al., AL-046 Burkholder, J.B., et al., AL-055 Burkholder, J.B., et al., AL-056 Burlaga, L.F., et al., SE-039 ♦Bums, D.J., et al., AR-015 Bums, D.J., et al., AR-086 Bums, D.J., et al., AR-087 *Bumside, R.G., et al., SE-012 ♦BURPEE, R.W., AO-009 BURPEE, R.W., et al., AO-006 ♦BURPEE, R.W., et al., AO-010 ♦BURPEE, R.W., et al., AO-01 1 ♦BURPEE, R.W., et al., AO-01 2 BURPEE, R.W., et al., AO-017 BURPEE, R.W., et aL, AO-028 Busalacchi, AJ., et al., PM-060 BUSHNELL, M., et al., AO-048 Busness, K., et al., AR-113 ♦BUTLER, J.H., et al., CM-005 Byrd, G.P., etal., WP-114 Byrd, G.P., et al., WP-155 ♦Byun, D.W., et al., AR-016 Cacciani, M., et al., CM-016 Caiazza, R., et al., WP-082 Caiazza, R., etal., WP-1 11 Caiazza, R., etal., WP-114 ♦CAIRNS, M.M., FS-09 Caldwell, D.R., et al., PM-031 Call, D.L, et al., AR-067 Callaghan, P., et al., AL-054 ♦Canfield, R.G., et al., SE-013 ♦CANNON, G.A., et al., PM-007 CANNON, G.A., et al., PM-035 ♦CARACENA, F., et al., NS-01 4 Carbone, R., et al., AO-043 Carder, K.L., et al., PM-066 ♦Carey, A.G., Jr., et al., AO-013 CARPENTER, C.N., et al., SE-036 Carpenter, J.R., et al., AL-017 CARRICK, H.J., et al., GL-023 Carriere, J.-M., et al., FS-034 CARSEY, T.P., et al., AO-024 CARTER, D.A., et al., AL-002 CARTER, D.A., et al., AL-003 CARTER, D.A., et al., AL-004 ♦CARTER, D.A., et al., AL-007 CARTER, D.A., et al., AL-014 CARTER, D.A., et al., AL-015 CARTER, D.A., et al., AL-018 CARTER, D.A., et al., AL-020 CARTER, D.A., et al., AL-021 CARTER, D.A., et al„ AL-022 CARTER, D.A., et al., AL-034 CARTER, D.A., et al., AL-042 CARTER, D.A., et al., AL-052 CARTER, D.A., et al., AL-053 CARTER, D.A., et al., AL-068 CARTER, D.A., et al., WP-097 CARTER, D.A., et al., WP-153 Casale, A., et al., SE-008 Cerezo, M., et al., WP-116 ♦Cess, R.D., et al., CM-006 CHADWICK, R.B., et al., FS-049 CHADW1CK, R.B., et al., WP-142 ♦Chadwick, W.W., Jr., et al., PM-008 Chadwick, W., et al., PM-015 Chan, K.R., et al., AL-030 Chandrasekar, V., et al., NS-002 203 Chandrasekar. V., et al., NS-010 *Chandrasekar, V., et al., NS-015 Chandrasekar, V., et al., NS-102 Chang, J.S., et al., AR-OIO Chang, J.S., et al., AR-Oll ♦Chang, J.S., et al., AR-017 Chang, J.S., et al., AR-090 Chang, J.S., et al., AR-107 Chang, J., et al., AR-019 Chang, J., et al., AR-113 Chang, P., et al., PM-027 *Changnon, S.A., AP-004 ♦Changnon, S.A., AP-005 ♦Changnon, S.A., AP-006 *Changnon, S.A., et al., AP-007 ♦Changnon, S.A., et al., AP-008 *Changnon, S.A., et al., AP-009 Changnon, S.A., et al., AP-020 Changnon, S.A., et al., AP-041 Chapman, B.C., et al., AO-080 ♦Chappell, C.F., et al.. FS-O10 Charlson, R.J., et al., PM-065 Charlson, R.J., et al., PM-069 *Chaumerliac, N., et al., FS-011 *Chaumerliac, N., et al., FS-012 Chen, J., et al., SE-009 Chen, J., et al., SE-010 *Chen, J., et al., SE-014 Chen, S.S., et al., NS-031 Chereskin, T.K., et al., PM-031 ♦CHERTOCK, B., et al., WP-015 Chester, R., et al., AR-059 ♦Cheung, T.K., et al., WP-016 ♦Cheung, T.K., et al., WP-017 Chin, C.S., et al., PM-009 CHING, J.K.S., et al., AR-001 ♦CHING, J.K.S., et al., AR-018 ♦CHING, J.K.S.. et al., AR-019 CHING, J.K.S., et al., AR-107 CHING, J.K.S., et al., AR-113 Christian, T.W., et al., WP-150 Christian, T.W., et al., WP-185 Christie, D.R., et al., NS-031 Christie, D.R., et al., NS-032 ♦Chu, S.-H., et al., AR-020 Church, H.W., et al., CM-027 ♦CHURNSIDE, J.H., WP-018 ♦CHURNSIDE, J.H., WP-019 ♦CHURNSIDE, J.H., et al., WP-020 ♦CHURNSIDE, J.H., et al., WP-021 ♦CHURNSIDE, J.H., et al., WP-022 ♦CHURNSIDE, J.H., et al., WP-023 CHURNSIDE, J.H., et al., WP-024 CHURNSIDE, J.H., et al., WP-073 ♦CHURNSIDE, J.H., et al., WP-163 CHURNSIDE, J.H., et al., WP-164 Cimorelli, A.J., et al., AR-015 Cimorelli, A.J., et al., AR-086 Clark, T.L., et al., AP-002 Qark, T.L., et al., AP-003 ♦CLARK, T.L., et al., AR-021 CLARK, T.L., et al., AR-029 CLARK, T.L., et al., AR-030 ♦CLARK. 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GF-012 ♦Garodz, L.J., et al., AR-045 Garvey, D. M., et al., CM-004 Garvey, D.M., et al., WP-Ol 1 Gatz, D.F., et al., AR-108 ♦GAYNOR, J.E., et al., AR-046 GAYNOR, J.E., et al., WP-045 ♦GAYNOR, J.E., et al., WP-047 ♦GAYNOR. J.E., et al., WP-048 ♦GAYNOR, J.E., et al., WP-049 ♦GAYNOR, J.E., et al., WP-050 GAYNOR, J.E., et al., WP-069 GAYNOR, J.E., et al., WP-083 GAYNOR, J.E., et al., WP-096 GAYNOR, J.E., et al., WP-097 GAYNOR, J.E., et al., WP-176 GAYNOR, J., et al., AL-042 GEISELMAN, T., et al., PM-051 GEISELMAN, T., et al., PM-053 GENDRON, J.F., et al., PM-053 GEORGES, T.M., et al., AO-059 ♦GEORGES, T.M., et al., WP-051 GEORGES, T.M., et al., WP-060 GEORGES, T.M., et al., WP-061 GEORGES, T.M., et al., WP-067 ♦GEORGES, T.M., et al., WP-170 ♦GEORGES, T.M., et al., WP-171 GEORGES, T.M., et al., WP-180 ♦Gerace, G.C., et al., WP-052 Ghil, M., et al., CM-042 Gierczak, T., et al., AL-006 ♦Gierczak, T., et al., AL-024 Gierczak, T., et al., AL-055 Gierczak, T., et al., AL-056 Gierczak, T., et al., AL-059 Gierczak, T., et al., AL-066 ♦Giese, B.S., et al., PM-020 Giese, B.S., et al., PM-025 ♦Giese, G.S., et al., AO-080 GILLETTE, D.A., et al., AR-053 GILLETTE, D.A., et al., AR-079 GILLETTE, D.A., et al., AR-116 GODOWITCH, J.M., et al., AR-096 GODOWITCH, J., et al.. AR-111 Goenaga. C, et al., AO-079 GONZALEZ, F.I., et al., PM-014 ♦GONZALEZ, F.I., et al., PM-021 ♦GONZALEZ, F.I., et al., PM-022 Gonzalez, N., et al., WP-129 Goodrich, B.R., et al., AR-094 Gorchakova, I. A., et al., GF-007 Gorman, E., et al., AR-110 Gorzelska, K., et al., AR-012 Gosling, J.T., et al., SE-015 ♦Gossard, E.E., et al., WP-053 ♦Gossard, E.E., et al., WP-054 ♦Gossard, E.E., et al., WP-055 ♦Gossard, E.E., et al., WP-172 ♦Gossard, E.E., et al., WP-173 Gosz, J.R., et al., WP-091 ♦GOTTLIEB, E.S., et al., GL-029 ♦GOVETT, M., FS-016 ♦Gozani, J., WP-056 ♦Gozani. J., WP-057 ♦Gozani, J., WP-174 Graber, H., et al., GL-019 Granata, T., et al., GL-018 GRASS, R.D., et al., CM-030 GRASS, R.D., etal., CM-031 Graves, D.S., et al., GF-016 GRAY, J., et al., PM-037 Green, J.L., et al., AL-063 ♦Greenblatt, G.D., et al., AL-025 Greene, H.G., et al., PM-016 208 GREENHUT, G.K., et al., FS-015 Greenstadt, E.W., et al., SE-015 GREER, M.S., et al., SE-027 GREER, M.S., et al., SE-029 Greiner, I., et al., GL-038 GRIFFIN, J.S., et al., AO-011 GRIFFIN, J.S., et al., AO-012 ♦GRIFFIN, J.S., et al., AO-028 Grom, R., et al., GL-038 ♦Grossman, R. L, et al., CM-017 ♦GRUBB, R.N., SE-025 GRUBB, R.N., et al., SE-038 Grund, C.J., et al., WP-125 *GUNTER, R.L., et al., AR-047 GUNTER, R.L., et al., AR-069 GUNTER, R.L., et al., CM-004 GUNTER, R.L., et al., WP-Ol 1 GUTMAN, G., et al., AR-028 HAGGERTY, J.A., et al., FS-008 Hain, K., et al., GL-038 Hales, J.M., et al., AR-053 Hall, W.D., et al., AP-003 ♦Hall, W.D., et al., AP-017 Hallett, J., et al., AO-074 Hallett, J., et al., AO-076 Hamilton, M, et al., GL-018 Han, S.M., et al., SE-017 Han, S.M., et al, SE-070 HANE, C.E., et al., NS-080 HANE, C.E., et al., NS-093 ♦Hansen, A.D.A., et al., AO-029 ♦Hansen, A.D.A., et al., AR-048 Hansen, A., et al., AR-078 ♦HANSEN, D.V., AO-030 ♦HANSEN, D.V., et al., AO-031 HANSEN, D.V., et al., AO-041 HANSEN, D.V., et al., AO-054 HANSEN, D.V., et al., PM-040 ♦Hanson, D.R., et al., AL-026 ♦Hanson, D.R., et al., AL-027 ♦Hanson, D.R., et al., AL-028 Hanson, H.P., et al., CM-008 Hanson, H.P., et al., WP-028 Hanson, K., et al., AO-049 Hanson, K., et al., AO-050 Hanson, K., et al., AR-070 Hanson, S., et al., PM-052 Harder, J.W., et al., CM-045 ♦Harder, J., et al., AL-029 ♦HARDESTY, R.M., et al., WP-058 ♦HARDESTY, R.M., et al., WP-059 HARDESTY, R.M., et al., WP-066 HARDESTY, R.M., et al., WP-074 HARDESTY, R.M., et al., WP-108 HARDESTY, R.M., et al., WP-110 HARDESTY, R.M., et al., WP-121 HARDESTY, R.M., et al., WP-125 HARDESTY, R.M., et al., WP-157 HARDESTY, R.M., et al., WP-158 HARDESTY, R.M., et al., WP-159 HARDESTY, R.M., et al., WP-166 ♦Harlan, J.A., et al., WP-060 ♦Harlan, J.A., et al., WP-061 HARRIS, J.M., et al., AR-066 HARRIS, J.M., et al., AR-084 HARRIS, J.M., et al., AR-117 HARRIS, J.M., et al., CM-027 HARRIS, J.M., et al., CM-032 HARRIS, J.M., et al., CM-040 HARRIS, J.M., et al., CM-045 HARRIS, J.M., et al., CM-047 ♦HARRISON, D.E., PM-023 ♦HARRISON, D.E., PM-024 HARRISON, D.E., et al., PM-020 ♦HARRISON, D.E., et al., PM-025 Harrison, R.H., et al., WP-020 Harrison, R., et al., AR-059 Harrold, C., et al., PM-016 ♦HARTMANN, H.C., GL-031 HARTMANN, H.C., et al., GL-016 ♦HARTMANN, H.C., et al., GL-032 HARTMANN, H.C., et al., GL-033 ♦HARVEY, G.R., et al., AO-032 HARVEY, G.R., et al., AO-066 ♦Hastie, D.R., et al., AO-033 Hastie, D.R., et al., AR-012 Hastie, D.R., et al., AR-100 Hatfield, J.L, et al., AR-005 Hawkins, J.D., et al., AO-071 Hayden, CM., et al., NS-069 Hayes, M.,etal.,WP-l 16 ♦HAYES, S.P., PM-026 ♦HAYES, S.P., et al., PM-027 ♦HAYES, S.P., et al., PM-028 ♦HAYES, S.P., et al., PM-029 ♦HAYES, S.P., et al., PM-030 HAYES, S.P., et al., PM-039 HAYES, S.P., et al., PM-041 HAYES, S.P., et al., PM-042 HAYES, S.P., et al., PM-043 HAZEN, D.A., et al., WP-133 Healy, K.R., et al., WP-034 ♦Hebert, D., et al., PM-031 Hecker, B., et al., PM-016 ♦HECKMAN, G.R., SE-026 HECKMAN, G.R., et al„ SE-037 HECKMAN, G.. et al., SE-063 ♦HEFFTER, J.L, et al., AR-049 HEFFTER, J.L, et al., CM-027 HEFFTER, J., et al., AR-028 ♦Heimbach, J.A., Jr., AP-018 HELD, I.M., et al., GF-022 HELD, I.M., et al., GF-034 HELD, I.M., et al., GF-039 ♦Helsdon, J.H., Jr., AP-019 Helsdon, J.H., Jr., et al., AP-013 ♦Hendon, H.H., et al., CM-018 ♦Hendon, H.H., et al., CM-019 Hendon, H.H., et al., CM-025 Henin, C, et al., PM-064 Henry, B., et al., AL-017 Heras, A.M., et al., SE-050 HERCHE, LR., et al.. GL-028 ♦HERCHE, LR., et al., GL-033 Herman, A., et al., AO-041 ♦HERMES, L.G., NS-037 209 ♦HERMES, L.G., NS-038 HERMES, L.G., et al., NS-034 ♦HERMES, L.G., et al., NS-039 Herwehe, J.A., et al., AR-134 Heymsfield, A.J., et al., AO-075 Hickey, J., et al., CM-038 ♦HICKS, B.B., AR-050 ♦HICKS, B.B., AR-051 ♦HICKS, B.B., et al., AR-052 ♦HICKS, B.B., et al., AR-053 ♦HICKS, B.B., et al., AR-054 HICKS. B.B., et al., AR-077 HICKS, B.B., et al., AR-108 HICKS, B.B., et al., AR-132 Hildebrand, P.H., et al., WP-025 Hildebrand, P.H., et al., WP-026 Hildebrand, P.H., et al., WP-074 Hildebrand, P., et al., AL-011 Hildebrand, P., et al., AL-012 ♦HILDNER, E., et al., SE-027 HILDNER, E., et al., SE-037 ♦HILL, R.J., WP-062 ♦HILL, R.J., WP-063 HILL, RJ., et al., WP-021 HILL, R.J., et al., WP-024 ♦HILL, R.J., et al., WP-064 HILL, R.J., et al., WP-091 HILL, R.J., et al., WP-123 HILL, R.J., et al., WP-124 HILL, RJ., et al., WP- 165 ♦HILL, V.J., et al., SE-028 ♦Hinckley, S., et al., PM-032 HINKELMAN, J.W., et al., FS-014 ♦HINKELMAN, J.W., et al., FS-017 HINKELMAN, J.W., et al., FS-018 Hipskind, R.S., et al., AL-013 HIRMAN, J.W., et al., SE-022 HIRMAN, J.W., et al., SE-028 ♦HIRMAN, J.W., et al., SE-029 ♦HITCHCOCK, G.L., et al., AO-034 Hoard, D.E., et al., AR-067 ♦HOECKER, W.H., et al., AR-055 ♦Hoerling, M.P., et al., CM-020 HOFMANN, D.J., et al., CM-009 ♦HOFMANN, DJ., et al., CM-021 HOFMANN, D.J., et al., CM-045 HOLLE, R.L., et al., NS-014 ♦HOLLE, R.L., et al., NS-040 HOLLE, R.L., et al., NS-051 HOLLE, R.L., et al., NS-052 HOLLE, R.L., et al., NS-053 HOLLE, R.L., et al., NS-054 HOLLE, R.L., et al., NS-090 HOLLE, R.L., et al., NS-091 HOLLE, R.L., et al., NS-092 HOLLE, R.L., et al., WP-078 HOLLE, R.L., et al., WP-079 HOLLE, R.L., et al., WP-080 Hollinger, S.E., et al., AL-008 ♦HoUinger, S.E., et al., AP-020 Hollinger, S.E., et al., AP-027 Holloway, E.T., et al., WP-007 Holt, B., et al., PM-058 ♦Hondl, K., NS-041 Hondl, K, et al., NS-033 Hondl, K, et al., NS-034 Horst, T., et al., AL-011 Horst, T., et al., AL-012 Horst, T., et al., WP-025 Horst, T., et al., WP-026 HOSKER, R.P., JR., et al., AR-054 HOSKER, R.P., JR., et al., AR-077 HOSKER, R.P., JR., et al., AR-108 ♦HOUSTON, S.H., et al., AO-035 Houze, R.A., Jr., et al., AO-046 HOWARD, C.J., et al., AL-044 HOWARD, C.J., et al., AL-046 HOWARD, C.J., et al., AL-064 HOWARD, K.W., et al., FS-045 HOWARD. K.W., et al., NS-001 ♦HOWARD, K.W., et al., NS-042 HOWARD, K.W., et al., NS-044 HOWARD, K.W., et al., NS-057 HOWARD, K.W., et al., NS-081 HOWARD, K.W., et al., NS-086 Hoyt, S., et al., AR-084 Hoyt, S., et al., CM-040 Hrebenach, S.D., et al., NS-006 Hsie, E.-Y., et al., AL-035 Hsie, E.-Y., et al., AL-036 Hsie, E.Y., et al., AL-057 Huang, C.Y., et al., SE-014 ♦HUBER, A.H., AR-056 ♦HUBER, A.H., et al., AR-057 ♦Hudson, E.F., et al., FS-018 ♦Huggins, A.W., et al., AP-021 Huggins, A.W., et al., AP-028 Huiling. Y., et al., PM-059 Hunt, J.C.R., et al., AR-122 ♦Hunter, S.M., et al., NS-043 Hunter, S.M., et al., NS-077 Hurt, J.A., et al., AR-009 ♦Huston, M.W., AP-022 ♦HADkkinen, S., GF-014 ♦HADkkinen, S., el al., GF-013 Ibler, M., et al., GL-038 ♦Ingraham, W.J., Jr., et al., PM-033 Intrieri, J.M., et al., WP-034 ♦Intrieri, J.M., et al., WP-065 ♦Intrieri. J.M., et al., WP-066 Intrieri, J.M., et al., WP-103 Intrieri, J.M., et al., WP-108 ♦Intrieri, J.M., et al., WP-175 ♦IRWIN, J.S., et al., AR-058 IRWIN, J.S., et al., AR-085 ♦IRWIN, J.S., et al., AR-131 Iturriaga, R., et al., GL-023 Jacob. D.J., et al.. AO-039 Jacob, D.J., et al., AR-060 JACOBSON, M.D., el al., WP-133 JAIN, M.H., et al., NS-081 JESUROGA, R.T., et al.. FS-017 ♦JESUROGA, R.T., et al, FS-019 Jewett, B.F.. et al.. FS-003 Jiang, F„ et al., CM-006 Jiang, S., et al, PM-064 210 Jickells, T.D., et al., AR-127 *Jickells, T., et al., AR-059 Joe, P.I., et al., WP-082 ♦JOHENGEN, T.H., et al., GL-034 JOHNS, E., et al., AO-055 "Johns, R.H., et al., NS-044 Johnson, D.F., et al., SE-040 Johnson, H.L., et al., AP-001 Johnson, H.L., et al., NS-035 ♦JOHNSON, J.E., et al., PM-034 JOHNSON. J.E., et al., PM-069 Johnson, J.M., et al., WP-1 16 Johnson, K.S., et al., PM-009 ♦Johnson, L.R., et al., AP-023 Johnson, R.H., et al., NS-084 Johnson, R.M., et al., SE-023 Johnston, M.V., et al., AL-038 Johnston, P.V., et al., AL-037 Johnstone, A.D., et al., SE-020 Jones, P.D., et al., CM-015 Jones, R.L., et al., AL-005 JONES, R.M., et al., AO-059 JONES, R.M., et al., WP-060 JONES, R.M., et al., WP-061 ♦JONES, R.M., et al., WP-067 JONES, R.M., et al., WP-170 JONES, R.M., et al., WP-1 80 ♦JONES, R.W., et al., AO-036 ♦JORDAN, J.R., et al., WP-068 JORDAN, J.R., et al., WP-097 JORDAN, J.R., et al., WP-1 16 JORDAN, J.R., et al., WP-1 18 JORDAN, J., et al., AL-042 JORGENSEN, D.P., et al., NS-004 ♦JORGENSEN, D.P., et al., NS-045 ♦JORGENSEN, D.P., et al., NS-046 JORGENSEN, D.P., et al., NS-048 JORGENSEN, D.P., et al., NS-058 JORGENSEN, D.P., et al., NS-080 ♦JOSELYN, J.A., SE-030 ♦JOSELYN, J. A., et al., SE-031 JOSELYN, J.A., et al., SE-033 JOSELYN, J.A., et al., SE-050 ♦Joseph, P.V., CM-022 ♦Joseph, P.V., et al., CM-023 ♦Joseph, P.V., et al., CM-024 ♦Joseph, P.V., et al., CM-025 Joseph, P.V., et al., CM-035 Jou, B. J.-D., et al.. NS-046 ♦Kahl, J.D., CM-026 ♦Kahl, J.D., et al, CM-027 Kahl, J.D., et al., CM-034 Kahl, J.D., et al., CM-046 ♦Kahler, S., SE-032 ♦KAIMAL, J.C., et al., WP-069 ♦KAIMAL, J.C., et al., WP-176 ♦KAIMAL, J.C., et al., WP-177 Kallos, G., et al., AR-122 Kalmbach, D., et al., SE-008 ♦Kamide, Y., et al., SE-033 Kaminski, S., et al., GL-038 Kane, M.-M., et al., AR-059 ♦Kantha, L.H., et al., GF-015 KAPLAN, J., et al., AO-016 *KAPLAN, J., et al., AO-037 Kapustin, V.N., et al., PM-069 Karl, T.R., et al., AP-041 ♦Karoly, D.J., et al., GF-016 ♦Karson, J.A., et al., AO-038 Kawa, S.R., et al., AL-005 ♦Kawa, S.R., et al., AL-030 Keenan, T., et al., AL-007 Keene, W.C., et al., AO-025 Keene, W.C., et al., AO-033 ♦Keene, W.C., et al., AO-039 Keene, W.C., et al., AO-066 Keene, W.C., et al., AR-009 Keene. W.C., et al.. AR-012 Keene. W.C., et al.. AR-044 ♦Keene. W.C.. et al., AR-060 Keene. W.C., et al., AR-069 Keene, W.C., et al., AR-100 Keene, W.. et al., AR-109 ♦Keighton, S.J., et al., NS-047 KELLER, D.L., et al., NS-023 KELLER, D.L., et al., NS-024 KELLER, D.L., et al, NS-025 KELLY, K.K., et al., AL-013 ♦KELLY, K.K., et al., AL-031 KELLY, K., etal.. PM-051 KELLY, K., et al., PM-053 Kelly, TJ., etal., AR-1 13 ♦KELSCH, M., FS-020 ♦Kennedy, P.E., et al., AP-024 Kenniston, G., et al., WP-049 Keqi, Y., et al., PM-067 Kerr, J.B., et al., AL-037 Key, R.M., et al., GF-036 Keyser, D., et al., WP-1 30 Khalsa, S.J.S., et al., FS-015 Khurshudyan, L.W., et al., AR-1 12 Khurshudyan, L.W., et al., AR-135 Kiehl, J.T., et al., GF-008 Kiladis, G.N., et al., CM-020 ♦Kiladis, G.N., et al., CM-028 Kim, Han, et al., AL-065 ♦Kim, Y.J., et al., AR-061 ♦Kim, Y.J., et al., AR-062 ♦Kim, Y.J., et al., AR-063 ♦Kim, Y.J., et al., AR-064 ♦Kim. Y.J., et al., AR-065 Kim, Y, et al., AR-109 KIM, Y., et al., CM -004 Kim, Y., et al., CM-043 KIM, Y., et al., WP-011 ♦KING, C.W., WP-070 ♦KING. C.W., WP-071 ♦KING. C.W., et al., WP-072 KING, C.W., et al., WP-183 Kiplinger, A.L., et al., SE-005 Kiplinger. A.L., et al.. SE-013 ♦Kiplinger, A.L., et al., SE-034 ♦Kiplinger, A.L., et al., SE-035 Kiplinger, A.L, et al., SE-069 Klazura, G.E., et al., NS-009 Klein, LW., et al., SE-039 211 Kleiner, J., et al., GL-038 Kley, D., et al., AL-013 ♦Klimowski, B.A., et al., AP-025 Klingle-Wilson, D., et al., NS-034 Knauer, G.A., et al., AO-034 Knoerr, K.R., et al., AR-024 Knoerr, K.R., et al., AR-130 KOENIG, G.L., et al., CM-031 Kogan, F., et al., AP-027 ♦KOMHYR, W.D., et al., CM-029 ♦KOMHYR, W.D., et al., CM-030 *KOMHYR, W.D., et al., CM-031 KOMHYR, W.D., et al., CM-037 *Kopcewicz, B., et al., AR-066 Kopcewicz, B., et al., AR-080 Kopcewicz, B., et al., AR-084 ♦Kopcewicz, B., et al., CM-032 KOPCEWICZ, B., et al., CM-O40 *Kopp, F.J., et al., AP-026 Kopp, F., et al., AP-040 Kopp, F, etal.. WP-115 *Kovacs, L.M., et al., WP-073 Kreiner, F.W., et al., CM-043 Krogslund, K.A., et al., PM-051 Krogslund, K.A., et al., PM-052 Krogslund, K.A., et al., PM-053 ♦KROPFLI, R.A., et al., WP-074 KROPFU, R.A., et al., WP-107 KROPFLI, R.A., et al., WP-114 KROPFU, R.A., et al., WP-151 Ku, J.-Y., et al., AR-097 Ku, J.-Y., et al., AR-098 Ku, J.-Y., et al., AR-099 Kulhanek, D., et al., SE-008 Kulikov, Ye.E., et al, PM-021 ♦Kumar, M., et al., AO-040 ♦KUNCHES, J.M., et al., SE-036 ♦KUNCHES, J.M., et al, SE-037 ♦Kunkel, K.E., et al„ AP-027 Kunkel, K.E., et al., AP-035 Kuo, Y.H., et al., AL-01 1 Kuo, Y.H., et al., AL-012 Kuo, Y.H., et al., WP-025 Kuo, Y.H., et al., WP-026 *Kuo, Y.H., et al., WP-075 *KURIHARA, Y., et al., GF-017 Kusner, Y.S., et al., GL-021 Labow, G., et al., SE-034 Lacis, A.A., et al, GF-008 Lagomarsino, R.J., et al., AR-035 ♦Lagos, P., et al., AO-041 Lamb, B.K., et al., AR-128 Lamb, B., et al., AR-053 LAMB, M.F., et al., PM-051 LAMB, M.F., et al., PM-053 Lamb, PJ., et al., AP-035 Lambright, H., et al., AP-008 Lampru, P.D., et al., FS-031 LANDRUM, P.F., et al., GL-020 ♦LANDRUM, P.F., et al., GL-035 ♦LANDRUM, P.F., et al., GL-036 ♦LANDRUM, P.F., et al., GL-037 LANDRUM, P.F., et al., GL-039 ♦LANG, P.M., et al., CM-033 Lang, R.F., et al., AO-066 Langdon, C, et al., GL-018 Langford, A.O., et al., AL-048 Langmuir, D., et al., AR-108 Lansford, H.H., et al., AR-017 Large, W.G.. et al., FS-015 Large, W.G., et al., PM-046 Larsen, S.E., et al., WP-036 Larsen, S.E., et al., WP-037 Larsen, S.E., et al., WP-090 ♦Ursen, S.E., et al., WP-178 Larson, R.E., et al., AO-029 Larson, R.E., et al., AR-048 ♦LATAITIS, R.J., WP-076 ♦LATAITIS, R.J., WP-077 LATAITIS, R.J., et al., WP-124 LATAITIS, R.J., et al., WP-163 LATAITIS, R.J., et al., WP-165 LATHROP, J.A., et al., CM-029 LATHROP, J.A., et al., CM-031 *Lau, K.-H., GF-018 ♦Lau, K.-H., et al., GF-019 LAU, N.-C, et al„ GF-019 ♦LAU, N.-C, et al., GF-020 LAVELLE, J.W., et al., PM-012 ♦LAVELLE, J.W., et al., PM-035 ♦LAVELLE, J.W., et al., PM-036 ♦LAW, D.C., FS-021 LAW, D.C., et al., FS-017 Law, D.C., et al., FS-049 LAW, D.C., et al., WP-095 LAW, D.C., et al., WP-142 ♦LAWRENCE, L.A., et al., PM-037 Lawrence, R.S., et al, WP-170 Laws, E.A., et al., PM-066 LAWSON, R.E., Jr., et al., AR-067 LAWSON, R.E., Jr., et al., AR-112 LAWSON, R.E., Jr., et al., AR-135 Lazarus, A.J., et al., SE-039 LEDUC, S.K., et al., AR-025 ♦Lee, J.T., et al., AR-067 Lee, R., et al., AR-113 *Lee, S., GF-021 ♦Lee, S., et al., GF-022 ♦Lee, W.-C, et al., AO-042 ♦Lee, W.-C, et al., AO-043 ♦LEINBACH, H., et al., SE-038 Lemen, J.R., et al., SE-069 LEMON, M.R., et al., PM-007 LeMone, M.A., et al., AO-003 LeMone, M.A., et al., NS-046 ♦LeMone, M.A., et al., NS-048 ♦Lenschow, D.H., et al., AR-132 Leonard, R.K., et al.. CM-030 ♦Lepping, R.F., et al., SE-039 LEWIS, J.M., et al., NS-036 ♦LEWIS, J.M., et al., NS-049 ♦LEWIS, J.M., et al., NS-050 ♦Lhermitte, R., et a]., AO-044 Li, F., et al., FS-015 ♦LI, S.-M., et al., CM-034 Licata, J.P., et al., SE-058 212 Liebmann, B., et al., CM-018 Liebmann, B., et al., CM-019 Liebmann, B., et al., CM-024 Liebmann, B., et al., CM-025 ♦Liebmann, B., et al., CM -035 Lilly, D.K., et al., NS-075 Lindberg, S.E., et al., AR-053 * Lindner, G., et al., GL-038 Lindsey, C, et al., AR-113 Linzey, R., et al., AR-108 Lipfert, F.W., et al., AR-108 *Lipschultz, F., et al., CM-036 ♦LIPSCHUTZ, R.C., et al., FS-022 LIPSCHUTZ, R.C., et al., FS-040 Litinetsky, A.V., et al., AO-005 Little, C.G., et al., WP-016 Little, C.G., et al., WP-017 Liu, A.K., et al., PM-058 *Liu, C.-M., et al., AL-032 Liu, M.-Y., et al., CM-052 LIU, P.C., et al., GL-019 LIU, S.C., et al., AL-032 LIU, S.C., et al., AL-035 LIU, S.C., et al., AL-036 LIU, S.C., et al., AL-057 LIU, S.C., et al., AR-053 Liu, S.C., et al., CM-045 Liu, S., et al., GF-032 Liu, X.M., et al., SE-016 Londergan, R.L., et al., AR-119 London, J., et al., SE-046 Long, A.B., et al., AP-021 ♦Long, A.B., et al., AP-028 *LONG, R.B., et al., AO-081 *LONG, R.B., et al., AO-082 LOPEZ, R.E., et al., NS-040 ♦LOPEZ, R.E., et al., NS-051 *LOPEZ, R.E., et al., NS-052 ♦LOPEZ, R.E., et al., NS-053 ♦LOPEZ, R.E., et al., NS-054 ♦LOPEZ, R.E., et al., NS-055 LOPEZ, R.E., et al., NS-090 LOPEZ, R.E., et al., NS-091 LOPEZ, R.E., et al., NS-092 ♦LOPEZ, R.E., et al., WP-078 ♦LOPEZ, R.E., et al., WP-079 ♦LOPEZ, R.E., et al., WP-080 Lovejoy, E.R., et al., AL-024 Luria, M., et al., AR-012 ♦Luria, M., et al., AR-068 ♦Luria, M., et al., AR-069 Luria, M., et al., AR-100 Luria, M., et al., AR-101 Luria, M., et al., AR-109 LUSK, C., et al., FS-031 Luxmoore, R.J., et al., AR-005 LYNCH, J., et al., PM-039 Maben, J.R., et al., AR-009 Maben, J., et al., AO-033 MACGORMAN, D.R., et al., NS-047 ♦MACGORMAN, D.R., et al., NS-056 MACGORMAN, D.R., et al., NS-099 MACHTA, L, et al., AR-055 MACKLIN, S.A., et al., PM-033 ♦MACKLIN, S.A., et al., PM-038 MADDOX, R.A., et al., NS-005 MADDOX, R.A., et al., NS-042 MADDOX, R.A., et al., NS-044 MADDOX, R.A., et al., NS-050 ♦MADDOX, R.A., et al., NS-057 ♦MADDOX, R.A., et al., NS-058 MADDOX, R.A., et al., NS-071 MADDOX, R.A., et al., NS-072 MADDOX, R.A., et al., NS-081 MADDOX, R.A., et aL, NS-082 Mader, C.L., et al., PM-022 Madronich, S., et al., AR-017 ♦MAHONEY, J., FS-023 Maier, M.W., et al., NS-051 ♦Maki, A.G., et al., AL-033 MALCZYK, J.M., et al., GL-027 Malle, S., et al., AO-033 Malle, S., et al., AR-100 Malm, W.C., et al., AR-089 ♦MANABE, S., GF-023 MANABE, S., et al., GF-003 MANABE, S., et al., GF-028 MANABE, S., et al., GF-041 MANABE, S., et al., GF-042 MANGUM, LJ., et al., PM-028 MANGUM, LJ., et al., PM-029 MANGUM, LJ., et al., PM-030 ♦MANGUM, L.J., et al., PM-039 MANGUM, LJ., et al., PM-043 MANGUM, L.J., et al., PM-059 MANGUM, L.J., et al.. PM-064 MANGUM, LJ., et al., PM-067 Manton, M., et al., AL-007 Mariano, A.J., et al., AO-071 MARKS, F.D., JR., et al., AO-006 MARKS, F.D., JR., et al., AO-007 MARKS, F.D., JR., et al., AO-01 1 MARKS, F.D., JR., et al., AO-012 MARKS, F.D., JR., et al., AO-017 MARKS, F.D., JR., et al., AO-027 MARKS, F.D., JR., et al., AO-028 MARKS, F.D., JR., et al., AO-042 MARKS, F.D., JR., et al.. AO-043 ♦MARKS, F.D., JR., et al., AO-045 ♦MARKS, F.D., JR., et al., AO-046 MARKS, F.D., JR., et al., AO-068 MARKS, F.D., JR., et al., AO-069 MARKS, F.D., JR., et al., AO-076 Marquette, W.H., et al., SE-047 Marra, J., et al., GL-018 MARROQUIN, A., et al., FS-017 ♦MARROQUIN, A., et al.. FS-024 Marshall, T.C., et al., NS-043 Marshall, T.C, et al., NS-077 MarshaU, T.C, et al., NS-078 Martens, P.C.H., et al., SE-071 Martin, C, et al., AL-011 Martin, C, et al., AL-012 Martin, C, et al., WP-025 Martin, C, et al., WP-026 ♦Martin, D.C., et al., PM-O70 213 Martin, J.C., et al., PM-070 Martin, R.C., et al., CM-033 Martin, R.F., Jr., et al., SE-01 1 ♦Martin, R.F., Jr., et al., SE-040 Martin, R.F., Jr., et al., SE-061 ♦MARTNER. B.E., WP-081 ♦MARTNER, B.E., et al., WP-082 MARTNER, B.E., et al., WP-155 Marwitz, J.D., et al., AP-025 Mascart, P., et al., FS-032 Mason, A.S., et al., CM-027 MASSOTH, GJ., et al., PM-009 MASSOTH, GJ., et al., PM-011 MASSOTH, GJ., et al., PM-017 MASSOTH, GJ., et al., PM-051 MASSOTH, GJ., et al., PM-053 *Matano, R.P., GF-024 ♦MATEJKA, T, NS-059 ♦MATEJKA, T, et al., NS-060 ♦MATEJKA, T, et al., NS-061 MATEJKA, T., et al., NS-087 Mathews, G.M., Jr., et al., WP-049 ♦Mathews, G.M., Jr., et al., WP-083 ♦Matrosov, S.Y., WP-084 ♦Matrosov, S.Y., WP-085 Matrosov, S.Y., et al., WP-053 Matrosov, S.Y., et al., WP-054 ♦MATT, D.R., et al., AR-133 Matthews, D., et al., AP-017 Mauch, L., et al., AR-089 ♦MAUL, G.A., AO-047 MAUL, G.A., et al., AO-031 MAUL, G.A., et al., AO-040 ♦MAUL, G.A., et al., AO-048 ♦MAUL, G.A., et al., AO-049 ♦MAUL, G.A., et al., AO-050 MAUL, G.A., et al., AO-051 MAUL, G.A., et al., AO-052 MAUL, G.A., et al., AO-053 MAUL, G.A., et al., AO-079 ♦MAUL, G.A., et al., AR-070 Maurice, P., et al., GF-001 ♦May, P.T., WP-086 May, P.T., et al., WP-092 May, P.T., et al., WP-098 May, P.T., et al., WP-099 May, P.T, et al., WP-126 May, P.T, et al., WP-138 May, P.T, et al., WP-141 May, P.T, et al., WP-152 ♦MAYER, D.A., et al., AO-051 ♦MAZUR, V., NS-062 ♦MAZUR, V., NS-063 MCAFEE, J.R., et al., AL-007 MCAFEE, J.R., et al., AL-018 MCAFEE, J.R., et al., AL-020 MCAFEE, J.R., et al., AL-021 MCAFEE, J.R., et al., AL-022 MCAFEE, J.R., et al., AL-023 ♦MCAFEE, J.R., et al., AL-034 McBean, G., et al., AR-122 ♦McCarthy, J.F., et aL, GL-039 ♦McCaul, E.W., Jr., et al., NS-064 McComas, DJ.. et al., SE-017 ♦McCORMICK, M.J., GL-040 McCORMICK, M.J., et al., GL-024 ♦McCORMICK, M.J., et al., GL-041 ♦McCoy, R.J., Jr., WP-179 McElroy, C.T., et al., AL-037 McElroy, J., et al., AR-123 McGee, E.S., et al., AR-108 McGillivary, P.A., et al., WP-001 McGillivary, P.A., et al., WP-022 McGillivary, P.A., et al., WP-023 ♦MCGINLEY, J.A., et al., FS-025 ♦MCGINLEY, J.A., et al., FS-026 ♦MCGINLEY, J.A., et al., FS-027 McGown, M.R., et al., AR-089 McGown, M., et al., AR-123 ♦MCGUIRK, M.P., et al., FS-028 McHenry, J.N., et al, AR-01 1 McHenry, J.N., et al., AR-030 ♦McHenry, J.N., et al., AR-071 McHugh, C.H., et al., PM-016 ♦McINTOSH, P.S., SE-041 McINTOSH, P.S., et al., SE-049 McINTOSH, P.S., et al., SE-064 McINTOSH, P.S., et al., SE-066 McINTOSH, P.S., et al., SE-067 McKeen, S.A., et al., AL-006 ♦McKeen, S.A., et al., AL-035 ♦McKeen, S.A., et al., AL-036 McKeen, S.A., et al., AL-045 McKeen, S.A., et al., AL-055 McKeen, S.A., et al., AL-056 McKenna, D.S., et al., AL-005 ♦McKenzie, R.L., et al., AL-037 ♦McKeown, P.J., et al., AL-038 ♦MCLEISH, W., et al., AO-052 ♦MCLEISH, W., et al., AO-053 McLeod, J.C., et al., FS-031 McMillan, L.M., et al., WP-126 McMillan, R.W., et al., WP-165 ♦McMILLEN, R.T., AR-072 McMILLEN, R.T., et al., AR-026 McMILLEN, R.T., et al., AR-027 ♦McMILLEN, R.T., et al., AR-073 McMurdie, L.A., et al., NS-069 McMurry, P.H., et al., AR-124 McNice, G.T., etal., WP-011 McNice, T, et al., CM-004 ♦McPeters. R.D., et al., CM-037 ♦MCPHADEN, M.J., et al., AO-054 MCPHADEN, M.J., et al., PM-018 MCPHADEN, M.J., et al., PM-027 McPHADEN, M.J., et al., PM-028 MCPHADEN, M.J., et al., PM-031 ♦McPHADEN, M.J., et al., PM-040 ♦McPHADEN, M.J., et al., PM-041 ♦McPHADEN, M.J., et al., PM-042 ♦McPHADEN, M.J., et al., PM-043 ♦McPHADEN, M.J., et al., PM-044 ♦McPHADEN, M.J., et al., PM-045 ♦MCPHADEN, M.J., et al., PM-046 McPHADEN, M.J., et al., PM-059 MCPHADEN, M.J., et al., PM-060 214 McPHADEN, M.J., et al., PM-062 MCTAGGART, K., et al., PM-039 MEITIN, J.G., et al., AP-030 MEITIN, J.G., et al., NS-066 MEITIN. J.G., et al., WP-088 *Meitin, R.J., et al., AP-029 *Meitin, R.J., et al., AP-030 Meitin, R.J., et al., AP-040 ♦MEITIN, R.J., et al., NS-065 *MEITIN, R.J., et al., NS-066 ♦Meitin, R.J., et al., WP-087 ♦Meitin, R.J., et al., WP-088 Meitin, R.J., et al., WP-1 15 Meleshko, V., et al., GF-028 Mellor, G.L, et al., GF-010 MeUor, G.L., et al., GF-01 1 MeUor, G.L., et al., GF-01 3 ♦Mellor, G.L., et al., GF-025 Mellouki, A., et al., AL-055 Mellouki, A., et al., AL-056 MENDONCA, B.G., et al., CM-014 Menzia, F.A., et al., PM-068 ♦Menzies, R.T., et al., WP-089 Merrill, J.T., et al., AO-025 Merrill, J.T., et al., AO-066 Merrill, J.T., et al., AR-044 Merrill, J. T., et al., AR-117 Merrill, J.T., et al., CM-047 MerriU, J.T., et al., PM-066 MERRITT, D.A., et al., FS-049 MERRITT, D.A., et al., WP-141 MERRITT, D.A., et al., WP-142 Mestayer, P.G., et al., WP-036 Mestayer, P.G., et al., WP-037 ♦Mestayer, P.G., et al., WP-090 Mestayer, P.G., et al., WP-178 Metz, S., et al., PM-017 Meyer-Wyk, M., et al., AR-107 * Meyer. E.L., et al., AR-074 MEYERS, T.P., et al., AR-004 MEYERS, T.P., et al., AR-006 MEYERS, T.P., et al., AR-007 MEYERS, T.P., et al., AR-053 MEYERS, T.P., et al., AR-054 ♦MEYERS, T.P., et al., AR-075 ♦MEYERS, T.P., et al., AR-076 ♦MEYERS, T.P., et al., AR-077 Middleton, P.B., et al., AR-017 ♦Mikkelsen, T, et al., AR-078 MILBURN, H.B., et al., PM-044 MUes, M.W., et al., CM-001 Milich, L.B., et al., AR-094 MiUard, B., et al., PM-059 Millard, R., et al., PM-064 MILLER, G.S., et al., GL-029 MILLER, G.S., et al., GL-041 MILLER, J.M., et al., AR-028 MILLER, J.M., et al., AR-059 MILLER, J.M., et al., AR-066 MILLER, J.M., et al., AR-127 MILLER, J., et al., CM-032 MILLER, P.A., et al., FS-004 ♦MILLER, P.A., et al., FS-029 MILLER, P.A., et al., FS-049 MILLER, P.A., et al., WP-142 ♦Milly, P.C.D., GF-026 ♦Milly, P.C.D., GF-027 Mingyu, Z., et al., AR-084 Mingyu, Z., et al., CM-040 ♦Mitchell, D.L., AP-031 ♦Mitchell, D.L., et al., AP-032 MITCHELL, E.D., et al., NS-033 ♦Mitchell, J.F.B., et al., GF-028 Mitchell, W., et al., PM-034 ♦Mlynczak, M.G., et al., AL-039 ♦Mlynczak, M.G., et al., AL-040 Molenar, J.V., et al., AR-089 ♦Molinari, J., et al., AO-083 ♦MOLINARJ, R.L., et al., AO-055 ♦MOLINARI, R.L., et al., AO-056 Moller, A.R., et al., NS-026 ♦Moller, A.R., et al., NS-067 ♦MONINGER. W.R.„ FS-030 ♦MONINGER, W.R., et al., FS-031 ♦Moore, D.I., et al., WP-091 Moore, W.S., et al., GF-036 ♦MORAN, K.P., et al., WP-092 ♦MORAN, K.P., et al., WP-093 ♦MORAN, K.P., et al., WP-094 ♦MORAN, K.P., et al., WP-095 MORAN, K.P., et al., WP-138 MORAN, K.P., et al., WP-141 MORAN, K.P., et al., WP-142 MORAN, K.P., et al., WP-154 MOREHEAD, N.R., et al., GL-047 Mori, Y., et al., WP-050 ♦Moritz, R.E., et al., PM-047 Mossotti, V.G., et al., AR-108 Moum, J.N., et al., PM-031 MOUNT, G., et al., AL-029 Mueller, S.F., et al., AR-053 ♦Mumane, R.J., et al., GF-029 MURPHY, D.M., et al., AL-038 Munay, J.W., et al., PM-036 ♦Musick, H.B., et al., AR-079 Musil, D.J., et al., AP-013 ♦Musil, D.J., et al., AP-033 NAGAMOTO, C., et al., AR-066 ♦NAGAMOTO, C., et al., AR-080 NAGAMOTO, C, et al., AR-084 NAGAMOTO, C., et al., AR-1 10 NAGAMOTO, C., et al., CM-032 NAGAMOTO, C, et al., CM-040 Naiping, L, et al., AR-084 Naiping, L., et al., CM-040 ♦Nair, U.S., AP-034 NAKAMURA, A.I., et al., PM-044 ♦NALEPA, T.F., GL-042 ♦NALEPA, T.F., GL-043 ♦NAPPO, C.J., AR-081 ♦NAPPO, C.J., AR-082 ♦NAPPO, C.J., et al., AR-083 ♦NAPPO, C.J., et al., AR-134 ♦Nastrom, G.D., et al.. AL-041 Nastrom, G.D., et al., AL-062 Nastrom, G.D., et al., AL-063 215 Nastrom, G.D., et al., AL-065 NATH, M.J., et al., GF-020 *Nealy, J.E., et al., SE-042 Nealy, J.E., et al., SE-053 *NEFF, W.D.. et al., AL-042 NEFF, W.D., et al., WP-008 *NEFF, W.D., et al., WP-096 ♦NEFF, W.D., et al., WP-097 Neilan, R.E., et al., WP-116 NEIMAN, P.J., et al., WP-029 *NEIMAN, PJ., et al., WP-098 ♦NEIMAN, PJ., et al., WP-099 ♦NEIMAN, PJ., et al., WP-100 NEIMAN, PJ., et al., WP-129 Nekrasov, I.V., et al., AR-112 Nekrasov, I.V., et al., AR-135 ♦Nelson, D.D., Jr., et al., AL-043 NELSON, D.W., et al., CM-014 ♦NELSON, D.W., et al., CM-038 Nelson. 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FS-031 ZWICKL, R.D., et al., SE-OOl ZWICKL, R.D., et al., SE-015 224 U.S. GOVERNMENT PRINTING OFFICE: 1992—674-065 PENN STATE UNIVERSITY LIBRARIES A000Q72fl32,U2