NOAA TM ERL BOMAP- 6 A UNITED STATES DEPARTMENT OF puucavion fi ~NQAA Technical Memorandum ERL BOMAP- 6 U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration Environmental Research Laboratories Ship’s Influence on Surface and Rawinsonde Temperatures During BOMEX WARREN M. WISNER | EC | ©/ WS Nag The BOMAP Office ROCKVILLE, MD. June 1971 NOAA TECHNICAL MEMORANDA Environmental Research Laboratories, BOMAP Series The Barbados Oceanographic and Meteorological Analysis Project (BOMAP) was established in the Research Laboratories of the Environmental Science Services Administration (ESSA), now NOAA, to coordinate the reduction of data collected during the Barbados Oceanographic and Meteorological Experiment (BOMEX), May, June, July 1969; to analyze these data, particularly those pertaining to the Sea-Air Interaction Program (the BOMEX Core Experiment) ; and to provide a central contact point for BOMEX information exchange and publication of BOMEX results. NOAA Technical Memoranda in the Environmental Research Laboratories BOMAP series document the methods, procedures, and techniques used to collect, analyze, and evaluate BOMEX data and facilitate the rapid dissemination of information that is preliminary in nature and subject to formal publication elsewhere at a later date. ERLTM-BOMAP 1 was published in the former series of ESSA Technical Memoranda, ESSA Research Laboratories. Beginning with ERL BOMAP-2, these publications are now part of the series of NOAA Technical Memoranda, Environmental Research Laboratories (ERL). Publications listed below are available from the National Technical In- formation Service, U.S. Department of Commerce, Sills Bldg., 5285 Port Royal Road, Springfield, Va. 22151. Price: $3.00 paper cover; $0.95 microfiche. Order by accession number shown in parenthesis at end of each entry. ESSA Technical Memoranda ERLTM-BOMAP 1 High-Level Cloud Photography Inventory, BOMEX Period IV, July 11-28, 1969. Vance A. Myers, September 1970. (PB-194 661) NOAA Technical Memoranda ERL BOMAP-2 A Statistical Data Plan for BOMEX. Theodore W. Horner, December 1970. (COM-71-00 188) ERL BOMAP-3 Mass, Momentum, and Energy Budget Equations for BOMAP Compu- tations. Eugene M. Rasmusson, January 1971. (COM-71-00 195) ERL BOMAP-4 High-Level Cloud Photography Inventory, BOMEX Period II, May 24-June 10, 1969. Vance A. Myers, March 1971. (COM-71- 00 574) ERL BOMAP-5 Preliminary Velocity Divergence Computations for BOMEX Volume Based on Aircraft Winds. Robert W. Reeves, April 1971. NN A A 0 0301 0040972 8 U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration Environmental Research Laboratories NOAA Technical Memorandum ERL BOMAP-6 SHIP'S INFLUENCE ON SURFACE AND RAWINSONDE TEMPERATURES DURING BOMEX Warren M. Wisner ATMOS, ; po S rie The BOMAP Office Rockville, Md. June 1971 UDGe Solo oOY col SON 724 sole S022 ool 08 e722 BOMEX ''1969.06.19-07.02" Seles) Meteorology 1550 Wind effects 501.724 Temperature observations 1007 122 Weather-observing ships .508.822 Radiosondes (263) Tropical Atlantic BOMEX BOMEX "1969.06.19-07.02" June 19-July 2, 1969 aba FOREWORD . ABSTRACT . 1. INTRODUCTION 2. INSTRUMENTATION J eOELEGEION OF DATA: 4. THEORY . 5. RESULTS 5.1 USC&GSS Oceanographer . .2 USC&GSS Ratnier . 5.3 USC§&GSS Mt. Mitchell 5.4 USC§&GSS Discoverer 5.5 USCGC Rockaway 6. CONCLUSIONS 7. ACKNOWLEDGMENTS 8. REFERENCES . TABLES . FIGURES CONTENTS abil Page FOREWORD This memorandum provides users of the BOMEX Temporary Data Archive some idea as to the problems associated with the surface temperature observations made during the Barbados Oceanographic and Meteorological Experiment (BOMEX). Published pending completion of final data reduction and more comprehensive crosscalibration studies, it may be used as a point of departure in designing further studies to arrive at selection and correction criteria for surface temperature data. liv SHIP'S INFLUENCE ON SURFACE AND RAWINSONDE TEMPERATURES DURING BOMEX Warren M. Wisner National Weather Service Climatologist for Missouri Columbia, Missouri 65201 Abstract. The Barbados Oceanographic and Meteorological Experiment (BOMEX), conducted in the summer of 1969, pro- vided an opportunity to examine the representativeness of data on sea-air interaction processes obtained from a variety of sensors. This paper presents a comparative analysis of observations made from conventional facilities located amidships on five fixed ships with data obtained from instruments mounted on a boom extending forward from the bow of each ship. Results based on temperature re- cordings indicate that the boom measurements probably are more reliable when the relative wind blows off the sea past the boom and then over the ship. When the wind off the sea blows over the ship and then over the boom, however, ship's influence is such that the boom and shipboard instrumenta- tion provide equally reliable measurements. 1. INTRODUCTION The Barbados Oceanographic and Meteorological Experiment (BOMEX) was de- signed for study of the joint behavior and interaction between the atmosphere and the ocean in tropical and subtropical waters through detailed observations in the upper1,000 mof the ocean and an atmospheric layer more than 6 km thick. The experiment was conducted in the western Atlantic, east of the is- land of Barbados, from May 3 to July 28, 1969. During the first three obser- vation periods - May 3 to May 15, May 24 to June 10, and June 19 to July 2 - observations were made within a 500-km by 500-km area, with five ships occupy- ing fixed positions at the four corners and in the center of the square (see fig. 1). During Period IV - July 11 to July 28 - the array was extended south- ward for investigation of tropical convective systems (see fig. 2). The five fixed ships used as observation platforms were the U.S. Coast and Geodetic Survey! ships Oceanographer, Rainier, Mt. Mitchell, and Discoverer and the U.S. Coast Guard cutter Rockaway. The mooring systems designed to maintain the ships at their designated locations failed -- the Mt. Mitchell's and Ratnier's at the very beginning of Period I, the Rockaway's early in Period II, and the Oceanographer's and Discoverer's later during the same period. After mooring failure, the ships used various modes of steaming and drifting in an attempt to remain as close as possible to their assigned positions. . TNow the National Ocean Survey. More than 2,500 rawinsondes were released during BOMEX from the five ships, with surface temperature, humidity, and wind being measured both manually by observers aboard ship and electronically by sensors mounted on a boom extending from the bow of each ship. This memorandum presents a pre- liminary comparison of the first 200 m of the rawinsonde temperature data with the manually observed and electronically recorded surface temperature data to determine (1) whether the ships' effects might have contaminated the lower levels of the rawinsonde data and (2) if contamination is evident, whether use of the electronically measured surface temperature data would tend to reduce or eliminate the contamination. As analyses in the Barbados Oceanographic and Meteorological Analysis Project (BOMAP) progress, it is anticipated that updated comparisons will be made and published. This first comparison, then, serves only to highlight some of the problems and to fur- nish some guidance to users of BOMEX data. 2. INSTRUMENTATION As noted in the Introduction, each ship was equipped with a boom surface instrumentation system and a rawinsonde tracking system. The boom extended outward about 10 m above the ocean surface and about 30° off the port bow (fig. 3). Sensors mounted on the boom measured dry- and wet-bulb tempera- tures, humidity, wind speed and direction, and other parameters. Each meas- urement, including that of barometric pressure and the ship's gyrocompass (true heading), were recorded every 30 sec on one channel of an analog tape by a signal conditioning and recording device (SCARD). The data analyzed here represent samples from BOMEX Period III (June 19 through July 2). During this period, rawinsondes were released approximately every 90 min (except at 0130 GMT) from the four U.S. Coast and Geodetic Sur- vey ships and every 3 hours from the U.S. Coast Guard cutter Rockaway, posi- tioned in the center of the BOMEX square. Each rawinsonde flight train con- sisted of two specially modified instruments carried aloft by the same balloon. The instruments were of standard Weather Bureau“ type, but modified so that one measured temperature only while the other measured humidity only. The temperature and humidity signals arriving at two separate receivers aboard each ship were recorded on analog tape by SCARD. At the time of each release, an observer visually obtained and manually recorded standard meteorological data from shipboard instruments. These data included dry- and wet-bulb temperatures, and wind speed and direction. 3. SELECTION OF DATA Ten-minute averages of the boom temperatures were chosen for compari- son with the temperatures recorded manually with a sling psychrometer on board each ship. The 10-min boom values with a listed time of 06:05:15 represent the averages of all 30-sec values recorded between 05:55:16 and 06:05:15. This average was selected for comparison with shipboard obser- vations between 0555 and 0605 GMT. The number of 30-sec samples in the 10- min averages used in this study varied from 10 to 21. aNoW the National Weather Service. To determine whether the effect of the ship environment was noticeable, the first 240 m of a set of rawinsonde flights for each ship were analyzed. The set consisted of 5-sec averages of temperature and humidity - derived from the SCARD analog recording sampled at the rate of 10 times per second - plotted against height. If the flight contained noise or bad references in the first 200 m it was not used. Several flights showed a strong lapse rate of from 3°C to 6°C per 100 m in the lowest 50 to 100 m, followed by a decrease to about 1°C per 100 m, which usually remained relatively uniform to the 200-m level. Therefore, the temperature value selected for comparison was the first value above this change in lapse rate. When such a change was not apparent, a temperature value near the 50-m level was selected, and the data were then extrapolated to deck height (9 m above the ocean surface) based on a lapse rate of 0.9°C per 100 m as determined for a homogeneous layer over the Caribbean Sea by Malkus (1958). To reduce the bias that would be introduced by using observations record- ed at different times by the temperature and humidity sensors, the value from one sensor was discarded when the corresponding value from the other was missing. 4. THEORY The superadiabatic lapse rate evident in the analyzed rawinsonde data (fig. 4) apparently was missing in soundings analyzed by other investigators of tropical phenomena. Brocks (Roll, 1965) showed that the superadiabatic layer just above the sea surface rarely extends above 23 m, and Malkus (1958) has given evidence that the layer above the superadiabatic is generally homo- geneous where the temperature profile roughly is characterized by an adiabatic lapse rate. The superadiabatic lapse rates in the analyzed BOMEX rawinsonde data may be artificial. The reason for such spurious rates may lie, for ex- ample, in that the ship heated its immediate environment or possibly in that rawinsonde instruments had been placed on the deck in sunlight and inadver- tently had been allowed to ''bake" before being released. Future comparison of these rawinsonde data with data obtained from dropsondes and from the boundary layer instrument package (BLIP) flown from the Oceanographer and Mt. Mitchell may help clarify this problem. If a ship were a contaminator of the environment in which temperature was measured on board, a wind across the ship toward the boom might spread contamination into the vicinity of the boom. The data were therefore grouped according to wind directions (fig. 5). For each scheduled rawinsonde release time, the differences between the shipboard and boom temperatures were then averaged and the release times subdivided into groups having similar differ- ences. For simplicity, and in order to keep the sample size of the groups large enough for significant results, the data from each ship were divided into two groups. The hypothesis that each of these data samples are representative mea- surements of the same environment could be tested statistically in various ways. For this study, the variance-ratio or F test, the Student's t test, and the Kolmogorov-Smirnov test were chosen. As the boom, shipboard, and rawinsonde temperatures were recorded by in- dependent systems, the data samples were assumed to be independent, although they may be correlated. It was further initially assumed that the data were drawn from normally distributed populations. Plots of sample data from the Oceanographer seem to support this assumption (fig. 6). The F test was applied to the null hypothesis that the sample variances in question are equally good estimates of the same population, i.e., that they are not significantly dif- ferent. The F statistic for sample variances can be calculated from ao (n] s)2/ (nj- 1) (ny s9°/ (np- 1) Ory if ny — Ny, F=s)°/s,? ; where 51° and $7/ are the sample estimates of the population variances for the two groups, and ny are the number of independent elements in the sam- ples, and nj-1 ee ng-1 ace the degrees of freedom. In working with time- sequenced temperature observations, one cannot assume these observations to be independent of each other. Brooks and Carruthers (1953) calculated this dependency or persistence by using an autocorrelation function, i.e., any correlation within a series in which the correlated values are a constant time interval apart. Almazan (1970) suggests the use of the sample autocor- relation function R(k), where k is the lag, to obtain an estimate of the number of independent observations in a sample N. This can be found by deter- mining the lag k where R(k) = 0; thus, Number of independent observations n = z The sample autocorrelation function is given by n- k oN R(k) = J (zi) . (2 (4+k)) K=011.2 ies) 2.5 Mi (1) where M is the maximum lag, and z; and Z(i+k) are the raw sample data points after normalizing by where S, is the sample standard deviation. For example, when the sample autocorrelation function goes to zero by the third lag, the ratio of N/2 or N/3 can be used as the number of indepen- dent observations n. The function R(k) is calculated under the assumption that all the elements in the-sample were selected at equally spaced time in- tervals, but some of the scheduled BOMEX rawinsondes were aborted, and the sample data used in this study are therefore not uniformly spaced in time. Because the author was unable to find a discussion in the literature dealing with autocorrelations and missing data, an experiment was designed to test whether the missing data would materially affect the autocorrelation function. First a series of random numbers were generated, and then a new series with a known persistence was developed by using a three-term running sum as follows: X(N) = y(N) + y(N+1) + y(N+2), N= 1,...,101, where y is the generated random series. The autocorrelation function of X was then calculated. To simulate the missing data, the uniform random number generator was used to generate a random number R:. When this number was less than 0.204, the corresponding number X; was eliminated from X. In this manner 18 observations were removed, and the hew X' series contained values that were no longer uniformly spaced. Values of z' equal to zero were then used to re- place the deleted data. The autocorrelation function for X' was calculated by use of equation (1) and the 1/(n-k) term was reduced by one each time one of the missing observations appeared in the cross product of ((2j) (Zj+k)). Figure 7 shows that the lag at which R(k) goes to zero is not materially changed when 20 percent of the data are missing. Chiu (1960) indicates that the shape of the spectra of temperatures and winds at a point are not changed materially when 10 percent of upper air data are replaced with a '"'best guess" by a researcher working from an analyzed chart. The null hypothesis was tested in all cases at the a = 0.05 level of Significance. As these were checks of equality, the two-tailed tests were used. Tabled values for the t and F distributions given by Yamane (1967) were applied in calculating critical values. When the null hypothesis is not rejected by the F test, i.e., the samples are from populations with similar variances, the null hypothesis that the sample means of the two samples are equally good estimates of the same popu- lation mean (or mean of the environment) can be tested by use of the Student's t distribution: (x, - Wy) - (2 - U2) nynz (ny+n2-2) t = a] — V nisi? + n282° mye 2 with n,} + no - 2 representing effective degrees of freedom. These n's are the adjusted lag coefficient values obtained from Nj/k and Nz/k. Since, according to the null hypothesis, yw, = U2, the equation becomes Xy - X2 t = ny + N92 V nysj? = nyS9° nynz (ny+nz-2) Because of the uncertainty concerning the validity of the assumptions made earlier with regard to the characteristics of the sample distributions, the nonparametric Kolmogorov-Smirnov (K-S) two-sample test (Siegel, 1956) was used to retest the null hypothesis that these data samples are measure- ments of the same environment. This test, which would be a much stronger one if the assumptions of independence and normality were not entirely valid, is based on the assumption that the cumulative frequency distributions of both samples will agree closely if both are from the same population, because the samples should show only random deviations from the population distribution. Wide differences in the sample cumulative frequency distributions, on the other hand, would suggest that the samples came from different populations and the null hypothesis would be rejected. For the K-S test, each sample is grouped into the same set of intervals (S(x)) and the maximum difference D between like intervals is the value tested: D = Maximum S(x)] - S(x) 5 The critical value of D, D., is the value that must be equaled or exceeded in order for the null hypothesis to be rejected. According to Smirnov (Siegel, 1956), De is calculated from Ny No Do = 1.36 ———— for a = 0.05. ee 2 Because this test requires that arbitrary intervals be established, and because too few intervals will tend to mask the maximum difference, the minimum number of intervals that would show the maximum differences in like intervals was determined. The best interval length was determined by study of intervals of 0.1°C, 0.2°C, 0.25°C, and 0.5°C based on sample boom and shipboard data, and the 0.2°C interval length was chosen as the most effi- cient for use in this study. 5. RESULTS 5.1 USC&GSS Oceanographer On the Oceanographer the shipboard observations were made aft of the exhaust stacks near the rawinsonde inflation shelter 220 ft from the bow where the boom was located. Figure 8 shows the average differences between the shipboard and boom temperatures at scheduled rawinsonde release times. When the wind was not blowing across or along the ship toward the boom, the shipboard temperatures were warmer than the boom temperatures between 1300 and 0300 GMT, and the boom temperatures generally were warmer but occasionally very slightly cooler than the temperatures observed on board the ship between 0430 and 1200 GMT. Therefore, these data were divided into 0400-1259 and 1300-0359 GMT subgroups. After similar analysis of cases when the wind was blowing across or along the ship toward the boom, the data were divided into 1000-2159 and 2200-0959 GMT subgroups. Table 1 shows the sample means and variances for the distributions of the observed temperatures used in each comparison. In both cases, the ship- board temperature averages warmer than the boom and rawinsonde values in the group that represent primarily daytime observations and cooler in the night- time group. The maximum difference is in the 1300-0359 GMT group, where the shipboard temperature averages 0.37°C warmer than the boom and 0.29°C warmer than the rawinsonde temperatures. When the wind is blowing across the ship toward the boom, the boom temperatures apparently tend to be more stable at night, as shown by the smaller standard deviation, Figure 9 was used to determine the lag coefficients that were applied to each sample to obtain the independent sample size and effective degrees of freedom. Results of the parametric F, Student's t, and the nonparametric K-S test are shown in table 2. When the wind is blowing across the ship toward the boom, the hypothesis that the boom, shipboard, and rawinsonde sensors are measuring the same environment is not rejected, and it would be difficult to say whether the boom or shipboard data would be better to use for comparison with the rawinsondes. When the wind is not blowing across the ship toward the boom, however, the hypothesis that the shipboard and boom sensors and the shipboard and rawinsonde sensors are measuring the same environment is rejected both by the Student's t test and the K-S test for the period 1300 to 0359 GMT. The temperature differences referred to earlier are significant. Comparison of the boom and rawinsonde data, however, does not reject the hypothesis according to the results of the tests discussed here. In summary, the boom data are probably the better measurement of the temperature environment being sampled by the rawinsonde during the day, par- ticularly when the wind is not blowing across the ship toward the boom. The 0400-1259 GMT subgroup, as in the case when the wind is blowing across the ship toward the boom, shows that the hypothesis is not rejected. Which ambient temperatures would be better to use with the rawinsondes is open to question; the ship's warmth appears to add 0.1°C to 0.2°C to the air passing over the ship. From table 2, the following assumptions can be made: (1) The boom temperature is the better one to use with the rawinsondes when the wind does not blow across the ship toward the boom. (2) The ship's and boom's temperatures are the same in the periods 1000-2159 and 2200-0959 GMT when the wind blows from the ship toward the boom but are not the same in the periods 1300-0359 and 0400-1259 GMT when the wind does not blow across the ship toward the boom. Figure 10 shows the cumulative probability curves for the shipboard-boom shipboard-rawinsonde, and boom-rawinsonde (°C) temperature comparisons for the 1300-0359 GMT subgroup of data for the case when the wind is not blowing across the ship toward the boom. The K-S maximum D value and the calculated D. values are indicated, based on data obtained between June 19 and July 2, 1969. 5.2 USC&GSS Ratnter On the Ratnter, the shipboard observations were made forward of the mid- section of the ship, either on the windward side of the pilot house or on the flying bridge above it about 72 ft from the bow of the ship. Because of the slope of the ship's deck, the pilot house was approximately the same height above the sea surface as the boom; the flying bridge was about 8 ft higher. The nighttime differences between the shipboard and boom temperatures shown in figure 11 were unexpected. When the wind is not across the ship to- ward the boom, the shipboard temperature averages almost 0.4°C cooler during the hours of darkness, while during daylight hours the two temperature aver- ages are almost identical. Therefore, the data obtained when the wind was not blowing across the ship toward the boom were subdivided into 1100-1959 and 2000-1059 GMI subgroups. When the wind blew across the ship toward the boom, the shipboard temperature generally was between 0.2°C and 0.5°C cooler than the boom temperature for the entire 24 hours. Because these data did not readily lend themselves to subdivision, they were retained as a single group. Table 3 shows the sample means and variances for the distributions of the observed temperatures used in each comparison. At night, and during the day when the wind blew across the ship toward the boom, the shipboard temper- atures also were colder than the adjusted rawinsonde temperatures. The reason for this is not immediately apparent, but probably lies in the effect of the ship on the environment. Another interesting feature is the higher variance of the rawinsonde temperature during the day than at night, which could have been caused by the scattered cloudiness and the daytime conditions that are typical over this area of the Atlantic Ocean. Figure 12 was used to obtain the lag coefficients for determining the independent sample size from which the critical values for the parametric Statistical tests were extracted. Results of the parametric and nonparametric tests applied to these data are shown in table 4. The first point of interest is the different types of decisions provided by these tests. The boom and rawinsonde data were plotted for the comparisons and, as figure 13 illustrates, the data are apparently not normally distributed. Thus, for the Ratnter, the emphasis should be placed on the K-S test results. The shipboard-boom comparisons for the 2000- 1059 GMT subgroup and the shipboard-rawinsonde comparisons for the 2000-1059 and 1100-1959 GMI subgroups show that this test rejects the null hypothesis (see table 4). The usefulness of the K-S test is pointed up by the fact that for the 1100-1959 GMT subgroup this test rejects the hypothesis for the ship- board-rawinsonde comparison but does not do so for the boom-rawinsonde com- parison, although table 3 shows the differences between the sample means to be almost identical (shipboard-rawinsonde being 0.15 and boom-rawinsonde 0.14). Figure 14 indicates slight but important differences in the comparisons for the 1100-1959 GMI subgroup. Thus, based on the K-S test, it appears that, when the wind is not blowing across the ship toward the boom, the boom data are the better measurement of the environment being sampled by the rawinsondes. When the wind does blow toward the boom, this test does not reject the hypo- thesis that the sensors are measuring the same environment. Therefore, it seems to matter little whether the boom or the shipboard data are used with the rawinsondes, although the boom does appear, on the average, to provide nighttime temperatures 0.1°C to 0.2°C higher than those measured on board the ship. 8 Figure 15 shows the cumulative probability curves for the shipboard, boom, and rawinsonde temperatures for the 2000-1059 GMT subgroup for the Ratnter. The maximum D value and the calculated D,. value are indicated, based on data obtained between June 19 and July 2. 5.3 USC§&GSS Mt. Mitchell The size of the Mt. Mitchell is the same as that of the Ratnter and the location of the ship observations relative to the boom as described in the preceding section also apply to the Mt. Mitchell. Because of this similarity, one would expect that the temperatures measured aboard the two ships would agree closely. However, the Mt. Mitchell shipboard temperatures show an un- usual diurnal variation (fig. 16). For example, for the data when the wind is blowing from the ship toward the boom (see table 5), which are divided into daytime and nighttime subgroups beginning at sunrise and sunset respec- tively, the average daytime shipboard temperature may be equal to the night- time average, while the daytime boom temperatures average 0.7°C warmer, and the adjusted rawinsonde temperatures average 0.5°C warmer. Also, of the 53 shipboard temperatures obtained when the wind was from the ship toward the boom, 20 fall between 27.20 and 27.39 (fig. 17), while no more than 10 boom temperatures fall into any single 0.2°C increment. If this peculiarity in the shipboard temperature cannot be explained logically, the possibility of using the boom values exclusively should be considered seriously. The fact that the ship's temperature modifies the air temperature passing over it and Maintains that control is one explanation. Even in this case, admittedly, the boom temperatures would better represent the environment. Figure 18 shows the lag coefficients used to derive the independent sample. Table 6, showing the results of the parametric and nonparemetric tests, indicates that the K-S test rejects the null hypothesis for the shipboard- boom comparison only for the 1100-2159 GMT subgroup. In all other comparisons, the hypothesis is not rejected, and therefore it would probably be better to use the boom data with the rawinsondes for all time periods. 5.4 USC§&GSS Discoverer On the Discoverer, the shipboard observations were made aft of the exhaust stacks near the rawinsonde inflation shelter about 220 ft from the bow of the ship and about the same distance above the ocean surface as the boom - conditions similar to those on the Oceanographer. Figure 19 shows the average differences between the shipboard and boom temperatures at rawin- sonde release times. As is evident from this figure, the shipboard tempera- ture is higher than the boom temperature for each hour in both groups and considerably higher during the night, except for the 0600 GMT release time when the wind was blowing across the ship toward the boom. These higher shipboard temperatures were probably caused by the exhaust gases from the ship that contaminated the shipboard observations; possibly these emissions were at a minimum at 0600 GMT. After analysis, the data for the period when the wind was blowing across the ship toward the boom were divided into 1400- 1959 and 2000-1359 GMT subgroups, and the other data into 2200-1259 and 1300- 2159 GMI subgroups. Figure 20 was used to obtain the lag coefficients for determining the independent sample number. The sample means and variances for the distribution of observed tempera- tures used in each comparison are given in table 7. The daytime shipboard and boom temperatures show very small variances, an indication of reasonably uniform conditions. The rawinsonde adjusted temperatures average almost 0.35°C cooler than the shipboard temperatures and only slightly cooler than the boom values. However, because of the large variation in the rawinsonde tempera» tures most of the F tests applied to daytime data reject the hypothesis that the shipboard-rawinsonde and boom-rawinsonde sensors were measuring the same environment (see table 8). The distribution of the rawinsonde temperatures is not normal, and the emphasis in this discussion is therefore placed on the K-S test, which rejects the null hypothesis for the shipboard-boom comparisons when the wind is not blowing from the ship toward the boom and for the 2000- 1359 GMI comparison when the wind is blowing from the ship toward the boom. Figure 21 presents in graphical form the results of the K-S test. This test also rejects the null hypothesis for the shipboard-rawinsonde 2200-1259 GMT subgroup when the wind is not blowing from the ship towards the boom, and both shipboard-rawinsonde groups when the wind is blowing from the ship toward the boom. Therefore, it appears that the boom measurements are the most represen- tative of the environment sampled by the rawinsondes, except for the 1300-2159 GMT subgroup with the wind not blowing across the ship toward the boom. When applied to this group, the K-S test does not reject the hypothesis that the shipboard-rawinsonde sensors are measuring the same environment, and hence it is of little consequence which data are used with the rawinsonde measurements. 5.5 USCGC Rockaway The Coast Guard cutter Rockaway has a much lower profile than the four Coast and Geodetic Survey ships. Because its main deck is only 19 ft above the ocean surface, the boom was mounted on a platform 4 ft above the main deck, placing it approximately at the same height as the area from which shipboard observations were made. This area was located aft of the exhaust stacks near the rawinsonde shelter some 280 ft from the ship's bow. Figure 22, showing the average differences between the shipboard and boom temperatures, indicates that the shipboard temperatures were generally warmer when the wind was not blowing across the ship toward the boom and cooler when the wind was blowing across the ship toward the boom. The reason for this is probably twofold: the addition of heated exhaust gases into (a) the observer's environment on the ship and (b) the boom environment. The data for the period when the wind was not blowing across the ship toward the boom were subdivided into 0800-2159 and 2200-0759 GMT subgroups; the other data, because they repre- sent only a few observations, were not subdivided. 10 Although the absolute differences are small, table 9 indicates a diurnal variation of 0.5°C in the shipboard temperature when the wind is not from the ship toward the boom, while the boom temperatures vary by about half that amount, which agrees closely with the diurnal variation in the rawinsonde temperatures. As is evident from table 10, the K-S test does not reject the null hypo- thesis in any of the comparisons, but the results of the parametric Student's t test disagrees with the K-S test results in two of the comparisons. Although statistically either choice would be acceptable, it probably would be prefer- able to use the boom data with the rawinsonde data when the wind is not blowing across the ship toward the boom and shipboard data when the wind is across the ship toward the boom. Figure 23 shows the autocorrelation functions for the boom, shipboard, and rawinsonde temperatures for the Rockaway. As this figure indicates, the autocorrelation function goes to zero after the second lag for the daytime data and after the fourth lag for the nighttime data. Here, as for the other ships, division of the number of observations N by 2 or 3 will provide an esti- mate of n, the number of independent samples to be used in making the various tests applied here. 6. CONCLUSIONS It has been established, primarily by use of the Kolmogorov-Smirnov nonparametric test, that for the majority of the cases examined here the manually recorded shipboard temperatures were not from the same environment as the electronically measured boom temperatures. The reason for this does not lie in the sensors, but primarily in the ship's influence on the environ- ment as indicated by the fact that the rawinsonde and boom instruments appar- ently were measuring the same environment. The difference between these measurements and the manually recorded shipboard temperatures showed a Sig- nificant dependence on wind direction relative to the ship-boom axis. This study, then, shows that if only one set of BOMEX temperature data is to be used with the rawinsonde measurements, that set should be from the boom observations. If it proves possible to choose data for each rawinsonde, a procedure similar to that presented in this paper could be used to make the proper choice. Use of the boom data alone would probably lead to biased results, as this study indicates that a ship does influence its temperature environment to a considerable extent, which in turn implies that the boom instrumentation is similarly affected. Future studies should consider redesign of the boom or replacement of the boom instrumentation by other sensors unless the boom can be oriented into the wind at all times. The temperature of the air over the ship is influenced at all hours, in- cluding nighttime. The ship's observed air temperatures are from 0.1°C to 0.2°C colder than those from the boom instruments. A possible, and plausible, explanation lies in the thermal capacity of the ship, with its superstructure and deck. The differences in the nighttime cooling - ship's temperature being lower than the boom temperature - are caused by the fact that the radiational cooling over the ship's structure produces a lower temperature than at the boom, which is located over the open sea, primarily because of the difference in Hat the thermal capacity between ship and sea. The sea is a large thermal reser- voir, while the ship with its lower thermal capacity will have a lower temper- ature than the temperature over the ocean, as will the air immediately adjacent to and above the ship. 7. ACKNOWLEDGMENTS The author is most grateful to Harold L. Crutcher and James A. Almazan for their careful review of the manuscript. 8. REFERENCES Almazan, James A., "The Spectrum of Atmospheric Turbulence for Horizontal Velocity Components in the Surface Bouncary Layer of a Sea Breeze Cir- culation," Report No. 22, Atmospheric Science Group, The University of Texas, Austin, Tex., 1970. Brooks, C.E.P., and Carruthers, N., Handbook of Statistical Methods in Meteorology, Her Majesty's Stationery Office, London, 1953. Chiu, Wan-Cheng, "The Wind and Temperature Spectra of the Upper Troposphere and Lower Stratosphere Over North America," Journal of Meteorology Vol. 17, No. 1, 1960; pp. 65-77. Malkus, J.S., "On the Structure of the Trade Wind Moist Layer,'' Papers in Physical Oceanography and Meteorology, Woods Hole Oceanographic Insti- tutions Vole is; No. 12, 1958: Roll, H.U., Physics of the Marine Atmosphere, Academic Press, New York, 1965, pp. 227-304. Siegel, Sidney, Nonparametric Statistics for the Behavioral Sciences, McGraw-Hill, New York, 1956. Yamane, Toro, Statistics, An Introductory Analysis, Harper and Row, New York, 1967. NY a 9T 61 8T Se SUOT}EA -Iasqo ‘ON 92°0 GSA Ov'o z7v'0 89°0 £S°0 Gz <0 6£°0 uoTJETASp prepueys £T°0 (0) ae) 9T°0 8T°0 9v°0 87°0 OT'O 9T°0 soueTIPA VOCIG me ULI 0c 2£é 30 Ze $9596) 309592 VOECLE vI°lL2 ueoW "UTMEY woog “UTMeY woog “uIMeYy woog “UTMeY woog SPUOSUTMEL “SA WOOg OT 61 8T Se SsuoT}eA -Z1asqo ‘ON 9° °0 V5, (0) Or’o Sv'0 89°0 ES) (6) Gz 0 ZSa0 uoTjeLlAop piepueys IL (0) WEE (0 9T°0 02°0 97 °0 Ze .0 (0) a) ¢o°0 ooueTIe/\ v6°9Z WE CY OEaLS vy Lz Se ES Be VETLGe oS ELC ure “UTMeY drys “UTMeY drys “UTMEY dtys “UTMEY drys epuosuTMeL "SA pLeOqaTYs 02 SC (KE vy SUOTIPA -1asqo ‘ON uOTIETAOP US co "0 ¢v°O sv'o 0s°0 SSa0 cv" 0 8S5°0 piepueis (0) ae) OT"O 61° 0 0c*0 SZ7°0 0c "0 8T°0 vc"O aoueTIEA 02596 89°97 OT 22 Ov’ LZ 65°92 ES39¢ OL LG wee VelG ue wood drys woog drys woog drys woog dtys wooq *SA pieoqatyus IND 6960-0022 IND 6ST72-O000T IND 6SZ7T-00t0 IND 6S20-00¢T wooq pxzemoj dtys sso1oe put wooq pzemoj dtys ssozlo9e OU PUTM 6961 ‘Zz ATNe-6T oune¢ ‘ITI potteg xgWod ‘Leydersouess9 sso89sn ‘suostieduod opuosutmer -wooq pue ‘apuosutmei-pizeoqdtys ‘wooq-pzeoqdtys Io} sxZojyowered uotjejtndod fo sajewtisy ‘fT oTqeL 13 *stsoyiyoddy [Inu oy Fo uotzoelaer sottduy , T8v°0 bs (0) Tvv'0 8ST°O £Sv°O (GAG AY Sora £v'°o 3892 S-y Oe o Lael COG 98°0- OCs 87° 0- MO Ga E> = 3592 2 OC's ve°l 61 °c MLL COU hey 1 [Moy 1 (Esl ys902 J SPUuUOSUTMEL *SA WOOYg I8v°0 88T°0 Tvv'o OLS 0 oSi%80 He © Gee) xTLZ¢°O 34892 S-% LOS GS Sits Tes SOG SIS HE 90RGs S905 LOG se NS Ona) OYA 35 Clea 82°C EN S6°2 ve°l T6'1 xITf°S 3892 d epuosutmert *SA pxreoqdtys Orr" 0 O0OT’O S8c "0 002°0 Ov’ 0 156 WY 06c°O =x 600°0 3892 S-¥ HORS le O a COG SS vAQ) (a5 SvaOm GORG 29E °° qse} 4 EGMC Gol LEE 80°T GEG ve°1 S0°Z 06°T 3897 4 wooq ‘SA pazeoqdtys on[Tea on[eA On[TBA on[eA on[Tea on[ea On[BA ON[TeA yes poet yes peiet [eo poret [eo peret -T3TIQ © -no TRO =f} 109—- tae -TiTIQ 0 -noTe) -T1TIQ 0 -noTe) IWS 6960-007 © IND 6ST72-O00T IND 6ScT-000 IND 6S£0-O00ET woog ptemoz drys ssozoe put wooq piemoi dtys ssozoe OU PUTM 696T ‘7 AIne-61T eunr “TTT potiedg xgwog ‘1eydersourss9 Sss930SN ‘Seanjeroduisa, opuosutTmMer pue ‘uwooq ‘preoqdtys suowe AjT[Tenba Fo stsoyzoddAy [T[Nu oy} But}se} TOF 35903 (S-y) AOUITUS-AOIOZOWTOY pue £389} 3 S,jUapnys £359} FY LO OT}JEL-9DULTIPA FO SONTEA TeOTATIO pue psaze[NoTe) ‘7 9TqGeL 14 EEE Soe 0 87°0 68°27 “UTMeY 6v°0 vz°0 BOELE woog 61 wesw IND 6927-0000 wooq ptemoq dtys ssoioe put 9530 Graal) S60 LC “UTMEY 92°0 £0°0 S0° 82 woog IES 1S 20, 1S 0) IND 6S6T-O0TT wooq piemoj dtys ssoise you put Ivo E10 OLREG “UTMeY Le-0 ae) WES The woog cS cv 0 IND 6S0T-0002 OpuoSUTMEL SUOTIEA -I19sqo ‘ON uoTeTASp piepueys dOUPTIE/ uray @puosuTmMeLl *SA WoOog SUOTJEA -I9SqO ‘ON uote TAep piepueys aoueTIeA uray “SA pieoqg SUOT}EA -IaSqoO ‘ON uote lAep piepueis QoOURTIEA ueoW wooqg ‘SA pieoq TUS Tus ——— a a a rs a ee a Os 6961 ‘2 AIN£-6T euNL ‘TIT potted XAWOd ‘ZeTUTeY Ss929SN ‘suostzeduos opuosutmex “woog pue ‘epuosutMet-pieoqdtys ‘wooq-pzeoqdtys tof sxZoyowexed uotierndod Fo saiewtisg “¢ oTqeL 15 stsoyzoddy [nu sy} Fo uotqzoeler sottduy , Ippo 8ST°O HO £6 09°0 Slee co. Tvv'o TELE (0 HO Gx GSaale LYS Se IL O[Tv’o SLC 0 COMCa #53 | Ga S0°72 80°T on[BA On[eA yes peel -T3TIQ 0 -ndTeD IND 6S£7-0000 wooq piemoy drys sso1se put Svc *0 00°C c8't Svcs "0 00°72 3 7 1E Sé270 00°¢ Sys | On[eA qeo -T3TI9 GF, (0) v7°T x80°9 x7Sb "0 SG als PAG 0 6c 0 9¢°0 Svat ONnTeA peret -no[e9 IND 6S6T-O0TT wooq piemoz drys ssotoe OU PUTM EIGaO) 66°T 6SaL LIC 10 66°T- 6Siel 0vz°0 86°T- OSE on[eAa qeo -T3119 vsT‘0 Te oH Soa 810 sat aie «19°T goead #595 °0 sesh ree aT 'P- ps2e72 Lia Tecan apuosutmer “sa pxreoqdtys «900 °0 aoaane oie ooo. kegs +68 °T peered wooq “SA pizeoqdtys on[TeA pore -no[Te) IND 6S0T-0002 6961 ‘Zz AIne-61 euner ‘TII potted XqWwod ‘LeTuTeY Ss980SN ‘seinjeredue, opuosutmer pue ‘uooq ‘pxreoqdtys suowe AjtTenbo Fo stsoyodAt{ [Inu 9y} 3uTAS9z IOF S90} (S-y) AOUTTUS-AOLOZOWTOY pue 1S59}3 1 s,}UepNIS £359} ¥y IO OT}JEI-J9dIUCTILA JO SONTLA [eITITID pue ps.el[NdT[e) “yp 9TdeL 16 SG 8T ST ie SUOTIEA -Iasqo ‘ON Iv'0 CzA0 Lv’°0 vv'o T9s0 v9°0 8v'°0 8r°0 uoT je TASp paiepueis LT°0 IT‘0 CO 61° 0 LS 0 Tv’0 GAD 5e (0) SOUPTIEA SVYLE “VL? 68° LZ ST" 82 CIBRLC MeLSwES VAS] LG GVELC uray *UTMEY woog *uUTMeY woog *“UIMeY woog *UTMeY woog opuosutTmMel *SA WoOog 61 ve ik GC SUOTIEA -I1asqo ‘ON Lv’0 8V°0 £v°0 6r'0 6S°0 OSi#0 8rv°0 8r°0 uoTIeTASp piepueis (GEAD £7°0O 61 °0 v2°0 So0 SZ°0 ZEL0 56 10) SOUP TIEA ESALG mes GaleC Tv Le SG 7Lc OLa iC mee Vane USELG MO GAL ueoyW “UTMEY drys “UTMeY drys “UTMeY drys “UTMEY drys opuosuTMeI “sq pxreOqaTys [ee O£ Le ce SUOTIBA -Iasqo ‘ON TS 30 TS°0 Son0 LS 0 09°0 Gs @ cv'O vv'o uoT}e TASp piepueis 97°0 9Z7°0 0s "0 Sen 0) 9¢°0 EAD, 81°00 6T°0 sour TIeA £0 82 GG. £2 SS Cum CMC ROLE SGPEC 62° L7 CGMLEG ueoW woog dtys woog drys wo og drys woog dtys wooq *sA pxreoqdtys IND 6STZ-O0TT IND 6901-0022 IND 6981-0020 IWS 6990-006T wooq piemo} drys ssoioe put wooqg piemoj dtys ssozoe OU PUTM 6961 ‘2 AIN(-6T OUuNL ‘TIT potted XAWO@ ‘TIPUDITW “IW SSOBOSN ‘suostzedwos apuosutmer -woog pue ‘opuosuTmei-pxeoqdtys ‘wooq-pieoqdtys ZIoJ sxojzowered uotjerndod Fo sajeutasqg “s 9eTqeL Ly *stsoyyodky Ttnu oy Fo uotzelexr sattdwy , £sv'O 682 °0 T0v 0 vLt°O L6v'°0 £9¢ 0 Oz ‘0 cvt’o 3892 S-» S0°2 ye = I 80°C- eOm SG oe OF Ol Ga T8°0- 35937 3 See Ue 1 8's Sie vy? 60°T HG COM 3897 d OpuosuTMeL *SA WOOg Ivv'0 Tcv'o £62 °0 SzI"0 0cv'0 T8z°0 OTr’0 LCG 10 3892 S-¥ Z0°?C- *CV o- LO Ca Sila le COGS 80°C- CON? TOON Ge 389} 3 86°T 90°T LO. 9CaL CSmG Ov't SI) a Ost 3892 d apuosutmez ‘SA paxeoqdtus 0zv 0 *ITZS°0 Tse °0 00T*O 0cr'"O 987 °0 Ove *O 0Sz°0 3893 S- vO°C- *V0°S- 50) Cs T8°0- 60°C- VO Gm LOSGs OSs 3593 2 SGaG 20-0 Livre 60°T (AIG Gi Il 61°C 9071 3892 J wooq *SA pxzeoqgdtys on[ea on[ea on[ea an[ea on[TeA ontea onTea on[ea ies power yes peel Te) peer, qeo powet -T3TIQ —--NaTeO -T2TIQ -noTeO -T}TIQ = -NoTe)D -T3TIQ — -No TBD IND 6STZ-O0TT IND 6501-0002 © IND 6S8T-0020 IND 6990-006T woog piemoj drys ssoioe putm wooq premoz dtys ssoise jou PputM me 6961 ‘2 Atn¢-6T eune “ITI potted XAWOd ‘TIAPYUDITIW “IW SSO8OSN ‘Seinqzerodwaz epuosutTmer pue ‘wooq ‘pireoqdtys Suowe AiITenbea Fo stsayyodAy [Nu ay} Butis9} IOF 34897 (S-y) AOUITUS-AOLOZOW TOY pue ‘1Ss932 2 s,qUapnys £359} 4 LO OT}JeI-VOUPTILA FO SONTeA [VITITID pue pazernotej “9 9T qe 18 OT ss’*0 EZ°0 of "0 80°0 89° LZ S8° LZ “UTMeY woog VI (E50, Sibaa) 92 0 £0°0 TS°Ze 98°42 “UTMEY drys cl 82°0 Zea0 80°0 £0°0 S8LLG 88 aLe woog dtys LIND 6S6T-O00VT is 6r'0 9b°0 ~Z°0 ZZ°0 ZO°LZ = v6" 9Z *UTMeY woog Ov zS°0 Sv'0 £Z70 0z°0 OO"Z2 9F°LZ “UT MeY dtys 1S 9S°0 ZS=0 TS'0 Zo°0 98°9Z 92°LZ woog drys IND 6S2T-000Z woog piemojz dtys ssoloe putM rT 0L°0 2°0 6v'0 ~=—- S00 So 1z Shor “UTMBeY woog 61 s9'0~— ‘TS 0 Or'0 ~—OT*0 09°LZ bl LZ ‘urmey = dys 61 6Z7°0 = 8£"0 g0'0 ~— v0 66°LZ -99°LZ woog drys LIND 6ST7-O00ST S/a0 5570 VEGIG “UTMEY TZ°0 0s*0 17h BYE “UTMeY 0s*0 SZ°0 ESeIG woog GC Ov" 0 He 68°92 woog vc 09°0 9¢°0 LREEC dtys 1S $9°0 cv'O SEaLe dtys IWS 6S2T-00772 woog ptemoj dtys ssoioe yOu PuTM apuos OPUOSUTMEL wooq SUOTIPA -19sqo ‘ON uoTje TAep prepueis SoUeTIPA uve UTMeI “SA WOOg SUOTIEA ~Iasqo *ON uoT}e TAP prepueis ooUueTIEA ueoW “sa pxeoqdtys SUOTIEA -ZIesqo “ON uOTIETASp piepueis OOUR TIA ue OW “SA preoqdtys 696T ‘Z AINeC-6I ounr SIT] potieg XAWOd ‘1eLeAODSTG SSDXN9SN ‘suostseduiods epuosuTMeL -wooqg pue ‘opuosutmei-pzeoqdtys ‘wooq-pieoqdtys 1oy sxzojowered uotzetndod Fo soejewtIsSy “L 9TqeL is) *stsoyzoddy [T[Inu 9y} Fo uotjoefex sottdwy 809°0 00s*0 9T¢°0 Soro OZ (G5 00°C- 69°0- LOG *CG°E SLL Cle vIs’o x£79°0 vor ’o #SZLv°0 90°Z #i5 °C 66°T #02°° Bbc OLE 69°T Soe Sss0 PH ape 7 (0) 697 °0 x01TS‘°O LOC 2530 66°T Simos 69°Z *8L°7C O9FT vo't an[ea on[ea on[ea ON[eA [eo peel qeo poeiet -TytIQ -noTe) = - TATA —-moTe9 IWS 6S61-O0VT wooq piemoz dtys sso1oe putM IND 6S£T-0007 vts’od stie= 80°C Ivv'0 OMG Lelpac Tvv'o ZOMG Lie? on[ea [eo -T3149 6c '°0 OT*T- x89 OT 89 °0 S8°0 xDI'D *97S 0 x0 °C LOOT On[eA poiet -noTe) IND 6STC-O0ET OTr’o ANA SOG hs 10, T0°¢ 86°T Svs *0 00°C 78° T OnTeA [eo -T3TID 607 °0 £8°0 (BT 55 *fVS "0 HOE AS Ov'l *LL9°0O UGS Sho) 7 an[eA poret no[Te9 IWD 6S7T-007Z wooq plemoj dtys ssoxroe you puTM 3892 S-y 3802 qs93 A QpuosuTMeI “SA WOOg 3802 S-¥ 7891 4 3891 J apuosutmel ‘SA pzeoqdtys 3897 S-y 3897 } 3892 J wooq ‘SA pieoqdtys 6961 ‘z Atne-6T eunr ‘TIT Potted X¥WOd ‘LeTeAODSTG SSN8NSN ‘seinqetedue} epuosutTmeL pue “Wood ‘paeoqdtys Suowe AyT[Tenbe Fo stsayzodky T[Nu dy But ise IOF 3892 (S-y) AOUITUS-AOLOZOUTOY pue ‘S02 3 Ss,jUepnys ‘3597 Y LO OTJEL-9dULTILA FO SONTeA TBOTITID pue poyetndTe) “sg 9TqeL 20 9¢°0 wor —- 0 145 3.0 45 60 7.5 9.0 105 LAG (HRS. } —- © © &@ an @ wu @o woo AUTOCORRELATION o _ © (— a — or —] & GW PP [—] an ao Se aecry ( ane | Sarre em (paReearen my [orseraae 0 #15 #30 45 60 7.5 90 105 LAG (HRS.} Figure 9. Autocorrelation funettons for boom, rawinsonde, and shtpboard daytime and nighttime temperatures for the Oceanographer, BOMEX Pertod III, June 19 - July 2, 1969. oi _ SHIPBOARD VS. BOOM | fy emcee =e! a = MAX + SHIPBOARD ae oee D p---- | | MAX D=0.4091 wee prov? CRITICAL D=0.2900 CUMULATIVE PROBABILITY 26.0 26.2 26.4 26.6 26.8 27.0 27.2 27.4 27.6 27.8 28.0 28.2 28.4 28.6 f ] SHIPBOARD VS. RAWINSONDE [a Soest = re cee. | St a eee ys hee = 6 RAWINSONDE—>| 4 | swpeoaao ee * 2 eee ne = 4 See ee 0 8 Geeta | ie MAX D=0.3714 32 | fe CRITICAL D=0.3251 1 para ae a 2 6.0 26.2 26.4 26.6 26.8 27.0 27.2 27.4 27.6 27.8 28.0 282 28.4 28.6 = BOOM VS. RAWINSONDE — wnee nn nen nen n enn eeeene MAX D=0.1429 CRITICAL D=0.3251 6.0 26.2 26.4 26.6 26.8 27.0 27.2 27.4 27.6 27.8 28.0 282 28.4 28.6 TEMPERATURE (°C) CUMULATIVE PROBABILITY re Ce ee ee Figure 10. Cumulative probability curves for shtpboard-boom, shtpboard- rawinsonde, and boom-rawinsonde comparisons for 1300-0359 GMT subgroup for the Oceanographer when the wind ts not across the ship toward the boom. The Kolmogorov-Smirnov maxtmum D and the calculated D, value are indicated. BOMEX Period III, June 19 - July 2, 1969. 32 WIND NOT ACROSS THE SHIP TOWARD THE BOOM DIFFERENCE (°C) | -.4 WIND ACROSS THE SHIP TOWARD THE BOOM 21 00 03 06 09s 12 15 18 SCHEDULED RAWINSONDE RELEASE TIME (GMT) Figure 11. Average differences between shipboard and boom temperatures at rawinsonde release times for the Ratnter, BOMEX Period III, June 19 - July 2, 1969. Posttive values indicate that the shipboard temperature is higher. 558 A BOOM O RAWINSONDE x SHIPBOARD = — < = es [—] eo [—] _— = 0 = = =3 -.4 a 0 15 30 45 60 7.5 9.0 105 LAG (HRS. 1.0 9 : NIGHT J 6 5 r 4 So 4 i = 3 = 2 [—] Ss 4 — = <« ee ee ee | aor wr = oO 0 15 3.0 45 60 75 9.0 10.5 LAG (HRS.) Figure 12. Autocorrelatton functions for boom, rawinsonde, and shtpboard daytime and ntghttime temperatures for the Ratnter, BOMEX Pertod III, June 19 - July 2, 1969. 34 FREQUENCY ]|]H 9 wo Fan ws oo BOOM 1100-2059 GMT SUBGROUP RAWINSONDE 2000-1059 GMT SUBGROUP BOOM 0000-2359 GMT SUBGROUP (B) (C} 26.6 27.0 27.4 27.8 28.2 28.6 27.027.227.4 27.8 28.2 286 29.0 27.4 27.8 28.2 28.6 TEMPERATURE (°C) Figure 13. Plots of sample temperature data from the Rainter, BOMEX Pertod III, June 19 - July 2, 1969. (A) Adjusted to deck hetght; (B) wind across ship toward boom; (C) wind not across ship toward boom (not shown for 2100-1059 GMT subgroup). — MAX D CRITICAL D =e SHIP-RAWIN, 0.4516 0.3454 al ROOM-RAWIN. 0.3226 0.3454 --f-- SHIPBOARD RAWINSONDE—>,_ CUMULATIVE PROBABILTY UNS w kami woos o 26.4 26.6 26.8 27.0 27.2 27.4 27.6 27.8 28.0 28.2 28.4 28.6 TEMPERATURE (°C) Figure 14. Cumulative probability curves for shtpboard, boom, and rawinsonde temperatures for 1100-1959 GMI subgroup for the Rainier. The Kolmogorov-Smirnov D and the calculated Dg value are indicated. BOMEX Pertod III, June 19 - July 2, 1969. B55 SHIPBOARD VS. BOOM aa CRITICAL D=0.2404 D a, Al. MAX D=0.4063 | Al 6.0 26.2 26.4 26.6 26.8 27.0 27.2 27.4 27.6 27.8 28.0 28.2 28.4 28.6 CUMULATIVE PROBABILITY ‘ SHIPBOARD VS. RAWINSONDE Pe asi ee = 8 SHIPBOARD ——— a * ee =. [ = 6 Se re w 5 f ~— RAWINSONDE = 4 MAX "7777" Ss 3 ie! =) ate MAX D=0.3654 ; poof if CRITICAL D=0.2667 0 = -.1 -.2 -.3 -.4 -.5 0 15 3.0 45 60 7.5 9.0 10.5 i LAG (HRS. | 9 3 NIGHT J 6 ee a5 = 4 = 3 = 2 o Si —_— =e 0 #15 30 45 60 75 90 10.5 LAG (HRS.) Figure 23. Autocorrelation funettons for boom, rawtnsonde, and shtpboard daytime and ntghttime temperatures for the Rockaway, BOMEX Pertod III, June 19 - July 2, 1969. 44