MID-PACIFIC OCEANOGRAPHY Part VI, Hawaiian Offshore Waters, December 1949- November 1951 SPECIAL SCIENTIFIC REPORT- FISHERIES No. 152 UNITED STATES DEPARTMENT OF THE INTERIOR FISH AND WILDLIFE SERVICE Explanatory Note The series embodies results of investigations, usually of restricted scope, intended to aid or direct management or utilization practices and as guides for administrative or legislative action. It is issued in limited quantities for the official use of Federal, State or cooperating Agencies and in processed form for econonny and to avoid delay in publication. United States Department of the Interior, Douglas McKay, Secretary Fish and Wildlife Service, John L. Farley, Director MID-PAGIFIC CCEAKOGRAPHY, PART VI HAWAIIAN OFFSHORE \VATERS D3CEM32R 19 49 -NOVEMBER 1951 By James W. McGary Oceanographer Pacific Oceanic Fishery Investigations Honolulu, T. H. Special Scientific Report: Fisheries No. 152 WASHINGTON: JUNE 1955 CONTENTS Procedures 1 Hu.gjh M. Smith cruise 1 8 General Mind pattern 9 Dynamic topography and geostrophic currents 9 Temperatures 9 3igoia-t 10 Salinity 10 Dissolved oxygen 10 Hufih M. Smith cruise 10 11 General wind pattern 11 Dynamic topography and geostrophic currents 11 Temperatures 12 Sigma-t 12 Salinj ty 13 Dissolved oxygen 13 Hugh M. Smith cruise 12 13 General wind pattern 13 Dynamic topography and geostrophic currents 13 GSK currents 14 Temperatures 14 Sigma-t 14 Salinity 15 Inorganic phosphate 15 Discussion 15 Acknowledgement s 18 Literature cited 19 List of figures 21 Figures 1-33 23 Remarks about the oceanographic data 56 Tabulated data, Hugh M. Smith cruise 1 57 Tabulated data, Hugh M. Smith cruise 10 75 Tabulated data, Hugh M. Smith cruise 12 IO9 This is the sixth of a series of descriptive reports on mid-Pacific oceanography by the Pacific Oceanic Fishery Investigations. The previous oceano- graphic reports presented and discussed data collected in the equatorial waters of the mid-Pacific. 1/ The present report covers the data collected during the first three of a seriea of six general oceanographic cruises of the research vessel Hugh M. 3ml th in the waters adjacent to the Hawaiian Islands. The periods covered by the oceanographic phases of the cruises were: cruise 1, December 13-21, 1949; cruise 10, July 19-31, 1951; and cruise 12, October 23 to November 2, 1951. The surveys of Hawaiian waters were initiated on the premise that the abundance and movements of the skipjack, Katsuwonus pelamis (Linnaeus), which forms the basis for the principal fishery of the islands, are controlled by events in the sea (Sette et al. 1954). The skipjack catches of the local fleet were used as a guide in planning the geographical and seasonal coverage of cruises 10 and 12. Cruise 10 was made when the fishery was at the summer peak, and cruise 12 was made during the middle of the fall decline. The observational programs of these cruises were designed to collect chemical, physical, and biological data which could be used to map the circulation pattern of the Island waters, i'roca the circulation pattern it was hoped to locate areas where enough vertical motion might occur to enrich the surface layers and in- crease biological activity, un each cruise observations of temperature and salinity suitable for computation of currents in the upper 1,000 m. were made as well as bathythermograph lowerings for details of the temperature structure in the upper 900 ft. (270 m. J . Other observations varied from cruise to cruise. Analyses for dissolved oxygen, which together with determinations of temperature and salinity help in tracing the circulation of different water masses and in their discussion, were made on cruises 1 and 10. Observations of inorganic phosphate, which is use- ful as an indicator of areas where turbulence and upwelling are sufficient to carry nutrients from the deep water to the euphotic zone, were made on cruise 12. Col- lections of zoGplankton, which serves to indicate areas of past enrichment, were made on cruises 10 and 12. A geomagnetic electrokinetograph (GSK) was used to make current measurements during cruise 12. Since the primary purpose of this report is to present the processed data in a form that is usable to POFI biologists and others interested in the hydrography of the area, the discussion of the results is purely descriptive. The major fea- tures of the circulation pattern and the results of the various observations-' are described separately for each cruise. In the final discussion the features re- current from cruise to cruise are explained in terms of the effect the island chain has on the general oceanic circulation in the area. These features are then exam- ined further for areas in which enrichment of the euphotic zone might occur. PR0CSDUR3S The vessel equipment, sampling methods, and most of the procedures used in processing the basic data have been described in the earlier reports by Cromwell (1951 and 1954), Austin (1954), and Stroup (1954). Minor changes which were made in the construction of cross sections, and procedures used in the construction of lateral (on sigma-t surfaces) and horizontal plots and in preparing types of data not used in the previous reports are described below. A slightly different procedure was used in the preparation of the salini- ty, dissolved oxygen, and inorganic phosphate profiles. In the previous reports, which were concerned primarily with meridional aspects, the principle of drawing 1/ Mid-Pacific Oceanography, Transequatorial Waters, Part I, Cromwell (1952); Part II, Cromwell (1954); Part III, Austin U954) ; Part IV, Stroup U954) ; Part V, Austin (1954). 2/ Except for zooplankton, which was the subject of a separate report by King and Hida (1954). sections so that there was consistency among the various fields was maintained as rigidly as possible iMontgomery 1954J . The station plots of each variable were drawn against temperature and their final shapes were determined by comparing them with the curves of the adjoining stations in the sections (Stroup 1954). In con- structing the profiles the isopleth intervals were read from these plots, but their final shape was determined by placing the profiles over the sigma-t surfaces and then, with careful consideration of observed values, fairing them in as nearly parallel to the sigma-t isopleths as practicable. In this report, however, all surrounding stations were considered in constructing each of the station curves, so greater consideration was given to the interpolated isopleth intervals. The values used in constructing the horizontal and lateral plots of dynamic topography, temperature, salinity, and sigma-t were interpolated from the individual station plots. Whenever it was possible, the spacing of the isolines on these plots was determined from the cross sections. The topography of the sigma-t surfaces was drawn on the assumption that the major components of the subsurface flow are isentropic lalong surfaces of equal potential densityj. The topography of four surfaces is shown for each cruise. The lowest valued surface varied from cruise to cruise and in each case was selected to depict the conditions at the lower limit of the quasi-homogeneous surface layer. The 24.0, 25.0, and 26.0 surfaces were selected as standard intervals to show the changes in topography and conditions between the surface and the intermediate water. When the variance of the salinity on these surfaces was great enough to be of value in tracing the circulation, the salinity contours were superimposed. Instead of using the dynamic height-^ cross sections to compute veloci- ties normal to the sections, as was done along the meridional sections described in the previous reports, dynamic height cross sections were used to construct plots of the geopotential topographyit/ for the 0- , 50-, 100- , 200- , and 300-declbar sur- faces. The spacing of the contours indicates the velocity relative to the 1,000- decibar surface. Only a single geostrophic velocity scale is shown for each of the hori- zontal plots of geopotential topography. The velocities were computed for 20 N. latitude using the tables and formula given in tl. 0. bl4 iLai'ond 1951J. This, taking into consideration the latitudinal difference, results in an apparent error of + 12 percent at the northern limits of the area (23 n.j and of -10 percent at the southern limit (18°N.). Considered alone, these appear to be errors of significant magnitude, however, if the indeterminable errors in direction and magnitude that could be caused by internal waves and topographical complications are also consid- ered, the mean velocity diagrams become more acceptable. Seiwell (1937) found that internal waves would cause fluctuations in dynamic height of I4 cm. per day. Defant (I95OJ found that apparent eddies appeared in the data for the coastal waters of California if allowances were not made for internal waves, in the waters treated in this study the proximity to land and the bottom topography would also cause de- viation of the actual currents from those indicated by the dynamic topography {Parr 1936J. In order to provide a general picture of the expected incident winds and currents for the cruise periods, monthly summaries of ships' reports of observed winds and currents have been prepared for the area east of (upstresun from) the U The dynamic height is used in oceanography to express the vertical dis- tance in gravitational potential between points in a selected isoDaric (pressure) surface and a reference surface where the pressure field and the gravitational field are assumed to coincide. It is usually expressed in dynamic meters, which represents the work performed when a unit mass is lifted approximately 1 m. (.98 m. at sea level) against the force of gravity. y The geopotential (dynamic) topography of the isobaric surfaces is simply a plot of the contours of equal dynamic height. The contours represent the lines along which a body can be moved without work being performed against the force of gravity. Hawaiian Islands. The wind data (table 1) were based on the U. 3. Kavy Hydro- graphic Office Pilot Charts (H. 0. 1401) and give the mean force and the percentage of the ships' wind observations that were reported for each cardinal and intercar- dinal point. The percentages were computed by averaging the values for the 5° squares between 15°N. and 25^. latitude at 150°W. to 155°V;'. longitude. Table 1. — Average force (Beaufort) of the wind and percentage of ship's observations reported from each of the cardinal and intercardinal points of the compass' in the area east of the Hav^aiian Islands. (H. 0. 1401) Direction January February March April May Ave. force Per- cent Ave. force Per- cent Ave. force Per- cent Ave. force Per- cent Ave. force Per- cent N NE E SE S SW W NV, Calm 3-4 4 3-4 3 3 3 4 4 5 29 42 8 4 2 4 4 2 4 4 3-4 3 3 3 4 3 4 40 34 9 6 3 2 2 <2 4 4 4 2-3 3 4 4-5 3 5 40 28 9 8 4 3 3 < 2 4-5 4 4 3 6 46 35 6 < 2 < 2 < 2 < 2 < 2 3 4 3-4 3 3 3 3 52 34 4 2 < 2 < 2 2 <2 Direction June July August September October Ave. Per- Ave. Per- Ave. Per- Ave. Per- Ave. Per- force cent force cent force cent force cent force cent N _ <2 3 2 4 4 3 2 4 3 NE 4 54 4 b4 4 56 3-4 56 4 47 £ 3 37 3 30 3 34 3-4 33 3-4 38 SS 3 4 3 2 3-4 5 3 3 4 6 S - <2 - <2 - <2 - <2 3 2 SW - <2 - <2 - <2 - < 2 <2 w - <2 - < 2 - <2 - <2 . <2 mi - <2 - < 2 - <2 - <2 _ <2 Calm - <2 - < 2 - <2 - < 2 - <2 Direction November December Annual average percent Ave. Per- Ave. Per- force cent force cent K 4 5 4-5 6 4 NE 4 47 4 40 48 E 3-4 29 3-4 30 34 SE 3 10 4 10 6 S 3 3 3 6 3 SW 3-4 2 2-3 2 < 2 W 2 2 <2 < 2 NW - <2 3 3 < 2 Calm - <2 <2 < 2 The monthly current data (table 2) were computed from the U. S. Navy Hydrographic Office Current Atlas of the Northeastern Pacific (H. 0. 570) in the same manner as the monthly wind data. The velocities are given in increments of 0.33 knots, which probably represents the limit of accuracy of the ships' observa- tions on which they are based. At the foot of each monthly column is a mean direc- tion for the month which has been taken from the current arrows given on the Pilot Charts (H. 0. 1401). Table 2. — Average velocity of the drift and the percentage of ship's ob- servation reported towards each of the cardinal and inter- cardinal points of the compass in the area east of the Hawaiian Islands computed from data given in the Atlas of Surface Currents of the Northeastern Pacific (H. 0. 570). Average drift was taken from H. 0. 1401 Direc- tion January February March April 1 Average Per- Average Per- Average Per- Average Per- velocity cent velocity cent velocity cent velocity cent N 0.34-0.66 10 0.34-0.66 11 0.34-0.66 13 0.00-0.66 11 NE 0.00-0.66 8 0.34-0.66 11 0.00-0.66 8 0.00-0.66 8 E 0.34-0.66 6 0.34-0.66 5 - <5 - <5 SS 0.00-0.66 7 0.34-0.66 7 - <5 - <5 s — <5 0.00-0.99 9 - <5 0.00-0.66 9 sw 0.34-0.66 12 0.00-0.66 18 0.34-0.66 15 0.34-0.66 8 w 0.34-0.66 28 0.34-0.66 21 0.34-0.66 33 0.34-0.66 38 NW 0.34-0.66 18 0.34-0.99 15 0.34-0.66 15 0.34-0.66 17 Nil - - <5 - 6 - <5 Ave.°T 310 305 30C 300 Direc- tion May June July August 1 Average Per- Average Per- Average Per- Average Per- velocity cent velocity cent velocity cent velocity cent N . <5 0.00-0.66 13 0.34-0.66 10 0.34-0.66 12 NE 0.34-0.66 5 0.34-0.66 9 0.34-0.66 5 - <5 B - <5 - < 5 - <5 - <5 SE - <5 - < 5 - <5 - "' ; S - <5 - < 5 - <5 - <5 SW 0.34-0.66 17 0.34-0.66 13 0.34-0.66 10 0.34-0.66 14 W 0.34-0.66 44 0.34-0.66 35 0.34-0.66 38 0.34-0.66 32 NW 0.34-0.99 13 0.34-0.66 19 0.34-0.66 20 0.34-0.66 20 Nil - 6 - 5 0.34-0.66 7 0.34-0.66 6 Ave.^T 280 295 295 295 Direc- tion September October November December Annual aver- age percent Average velocity Per- cent Average velocity Per- cent Average velocity Per- cent Average velocity Per- cent N NE E SE S SW W NW Nil 0.34-0.66 0.34-0.66 0.34-0.66 0.34-0.66 0.34-0.66 0.34-0.66 11 5 < 5 < 5 < 5 10 38 20 6 0.34-0.66 0.34-0.66 0.00-0.33 0.34-0.66 0.34-0.66 0.34-0.66 10 8 <5 8 <5 15 34 19 6 0.00-0.66 0.34-0.66 0.34-0.66 0.34-0.66 0.34-0.66 0.34-0.66 10 <5 6 <5 <5 21 32 12 9 0.00-0.66 0.34-0.66 0.34-0.66 0.34-0.99 0.00-0.66 7 <5 5 <5 <5 16 36 18 6 10 9 <5 <5 <5 14 34 17 6 Ave.°T 260 280 270 290 To show the short-period fluctuations in the currents incident to the islands that could have been expected if the effect of the wind were assumed to be Instantaneous, tables of daily wind and current (tables 3-5) were computed for the week preceding and for the period of the cruises. The choice of the 1-week period before the cruise was purely arbitrary, and the data are merely included as back- ground. The winds were computed from the pressure gradients indicated by the U. S. Weather Bureau Synoptic Weather Maps and in turn were used to compute the currents. A point at 20°N. latitude, 15i2i°W. longitude was selected as a standard reference because the majority of the winds were easterly. Inspection of the charts indi- cated that one value per day is sufficient to reflect the major changes in the pressure pattern, so only the 1200Z charts were used. Table 3. — Cruise 1, computed surface winds and currents at 20 N. and 155°W. Winds were computed from 12002, U. S. Weather Bureau Synoptic Charts by the method described in U. S. Navy Hydrographic Office Miscellaneous Publication 11,275. Currents were computed by Ekman's formulae Date Wind Dir.°T Wind velocity kt. Wind fetch miles Current Dir. °T Current velocity kt. Remarks 12-7-49 090 14 1200 315 .3 12-8-49 145 11 480 010 .2 Low centered at 23°N.- 169°W. 12-9-49 120 15 390 345 .3 Low centered at 24°N.- 164°W. 12-10-49 115 17 510 340 .4 Stationary front 20°N.- 160*^. to 17*°N.-165°W. 12-11-49 120 13 470 345 .3 12-12-49 105 13 650 330 .3 12-13-49 090 25 1450 315 .5 12-14-49 075 20 750 300 .4 12-15-49 120 11 560 345 .2 Low centered at 29°N.- 164°W. 12-16-49 120 18 600 345 .4 Low centered at 29°N.- 167°W. 12-17-49 120 15 500 345 .3 Shallow trough along 165°W. 12-18-49 110 9 900 335 .2 Shallow trough along 160^^;. 12-19-49 110 9 600 335 .2 Low forming over the islands. 12-20-49 12-21-49 - - - - - Trough over the islands well developed trade winds east of the is- lands. The wind velocities were obtained by first computing the geostrophic wind from the weather charts and then multiplying it by a reduction factor which took into account the curvature of the isobars (H. 0. Misc. Pub. 11,275). Most of the time the islands were under the influence of the Eastern North Pacific High, and, as indicated by the large fetches, the isobars had little curvature, so 0.67, the value for Isobars of small anti-cyclonic curvature, was used. During the periods when lows or troughs were over the islands 0.60, the factor for isobars of great cyclonic curvature, was used. Whenever possible, the reliability of these computed values was checked by comparing them v.ith ships' observations. With few exceptions, the difference was not more than one force of the Beaufort scale or one compass point, which are considered satisfactory checks. Table 4. --Cruise 10, computed surface winds and currents at 20 N. , 155°W. Winds were computed from the 12002, U. S. V/eather Bureau Synoptic Charts by the method described in the U. S. Kydrographic Office Miscellaneous Publication 11,275. Currents were computed by Ekraan's formulae Date Wind Dir.°T Wind velocity kt. Wind fetch miles Current Dir. °T Current velocity kt. Remarks 7-9-51 095 9 490 320 .2 7-10-51 080 13 960 315 .3 7-11-51 095 17 600 320 .4 7-12-51 090 13 810 315 .3 7-13-51 085 20 900 310 .4 7-14-51 080 13 1150 305 .3 7-15-51 110 10 1300 335 .2 7-16-51 075 13 150 300 .3 V.ave in isobars E. of the islands. 7-17-51 080 13 faOO 305 .3 7-18-51 100 14 600 325 .3 7-19-51 090 18 750 315 .4 7-20-51 120 13 300 345 .3 Wave in isobars W. of the islands. 7-21-51 090 15 1150 315 .3 7-22-51 105 17 1250 330 .4 7-23-51 105 15 750 330 .3 7-24-51 095 14 750 320 .3 7-25-51 095 14 650 320 .3 7-26-51 090 13 850 315 .3 7-27-51 090 14 1250 315 .3 7-28-51 080 13 1100 305 .3 7-29-51 090 13 1100 315 • 3 7-30-51 105 10 600 330 .2 7-31-51 100 13 550 325 .3 Table 5. — Cruise 12, computed surface winds and currents at 20^^., 155°W. Winds were computed from the 1200Z U. 3. Weather Bureau Synoptic Charts by the method described in the U. 3. Hydrographic Office Miscellaneous Publication 11,275. Currents were computed by Ekman's formulae Date Wind Dir.°T Wind velocity kt. Wind fetch miles Current Dir. °T Current velocity kt. Remarks 10-13-51 075 9 1050 300 .2 10-14-51 090 11 800 315 .2 10-15-51 095 14 600 320 .3 10-16-51 125 10 500 350 .2 10-17-51 115 10 500 340 .2 10-18-51 120 11 450 345 .2 10-19-51 100 14 500 325 .3 10-20-51 100 14 800 325 .3 10-21-51 090 11 750 315 .2 10-22-51 070 14 650 295 .3 10-23-51 080 14 750 305 .3 10-24-51 095 13 1250 320 .3 10-25-51 105 10 1100 330 .2 10-26-51 120 11 500 345 .2 10-27-51 130 8 600 355 .2 Low at 25°N,-157°W. 10-28-51 170 9 300 035 .2 Low at 26°N.-163°W. 10-29-51 150 13 500 015 .3 Low 'at 27°N.-lt>l°W. 10-30-51 150 9 50U 015 .2 Trough along 163°W. 10-31-51 - - - - - Small trough over the hawaiian Islands. 11-1-51 170 9 100 035 .2 Deep trough over the Hawaiian Islands. Front 30 miles north of Kauai. The fetch was computed and included as an index to the extent of the v.lnd field. It was the distance between 20°N. , 150°W. and the point where the curvature of the isobars increased until they made an angle greater than 30*^ with their direction at 20°N., 150°V.'. 6 The wind direction was obtained by applying the rule that outside the tropics in the Northern Hemisphere the wind over the ocean deviates 80 to the right of the pressure gradient. The ocean current velocities and directions were computed from the wind data using the empirical relationships derived by Ekman (Sverdrup et al. 1946, p. 494) and assuming that the wind forces acted instantaneously. The formula used to compute the velocities was V =0.0127 "Vain If where v m current velocity, W ■ wind velocity, and v « latitude. The direction was obtained by applying the rule that the current is directed 45° to the right of the wind in the Northern Hemisphere. During cruise 12 surface or near-surface current measurements were made with the von Arx (19$C) GEK. The current vectors were corrected for the error due to the difference in depth (droop) of the two electrodes. This correction con- sisted of a vector directed towards the magnetic Equator. The magnitude of this vector was dependent upon the ship's speed, the direction of the ship's motion, and the amount of droop, and was computed by means of formulae derived by John Knauss (personeil communication) .2/ HUGH M. SMITH CRUISE 1 Cruise 1 of the HuRh M. Smith was planned primarily as a shakedown cruise for the vessel, gear, and personnel. Therefore, the station pattern was designed to take advantage of the lee provided by the island of Hawaii. Figure 1 is a chart of the station positions. The solid lines indicate the lines along which cross sections of bathythermograph temperatures (°r) , sigma-t, salinity (°/oo) , and dy- namic topography (m. ) have been drawn. Stations 8A and 8B were occupied several days before adjoining stations in the regular series, so their data were not used in the analyses but are included in the tabulattd data. Since the discussion of the various fields of a water mass is more under- standable when the general character of the flow pattern has been established, the usual procedure of presenting the results of the cruises is reversed in this report. The winds and computed currents are discussed first. This is followed by the dy- namic topography and the geostrophic currents. Then the fields of temperature, density, salinity, and dissolved oxygen are presented in the order named. iJ The magnitude of the droop was calculated from observations made at the earth's magnetic equator on a later cruise. The formula used was "^c Hg d=t;h7s where D = droop S = distance between electrodes Vc = resultant signal vector ▼s = speed of the ship Hh = horizonted magnetic field component H3 = magnetic field component set on the GEK. Using the computed values of D, the magnitudes of the corrective vectors were then computed by the formula, D Hh - V = vt - vs— g- u where V = true current Vt = current calculated u = unit vector in the opposite direction of Hj^ in the Northern Hemisphere and the same direction in the southern. General Wind Pattern The wind pattern {table 3) over the Islands was influenced by two low pressure systems which developed in the area to the west. The first, December 7 to 10, did not pass over the islands. The second, which first appeared on the U. 3. Weather Bureau map of December 15, moved in over the islands and persisted until the end of the cruise. As a result of these lows, the winds were more southerly than normal for December (table IJ. When they are transformed into cur- rent direction by the 45° cum sole rule, the inferred currents are 10° to 80° to the right of the 290°T average indicated by the Pilot Chart. As mentioned above, during the process of checking the reliability of the winds computed from the synoptic charts (USUB) these winds were compared to the observed winds recorded in the bathythermograph logs. The results were rather startling and it at first appeared that the computed winds were unreliable. How- ever, because of excellent agreement between computed and observed winds in the upwind area and the fact that almost all of the BT observations were in the lee of Hawaii, it has been suggested that the variance was the result of the "barrier" effect of the high mountains of the island (Saul Price, U3WB, personal communica- tion). Data from this and subsequent cruises are now being analyzed to determine the nature of the effect. Dynamic Topography and Geostrophic Currents The dynamic heights are shown in figure 2 and the geopotential topography in figure 3- The dotted lines in the vicinity of station 1 represent extrapolated values necessary because of bottle failures below 600 m. at station 1 and are in- tended merely to indicate the direction of flow. The heights are based on the rather dubious assumption that the height of the 700-decibar (m.) surface at sta- tion 1 is the mean of the heights at stations 2 and 8. This method was used be- cause the extrapolated values of salinity and temperature at station 1 provided extremely large dynamic heights, indicating currents of up to 1.6 K:nots In the surface layers. The actual currents were probably somev.here between those indi- cated by the contour in the figures and those indicated by the extrapolated temper- atures and salinities. The geopotential topography shows an extremely well-developed cyclonic^/ eddy. At the surface it was centered at station 6, but it shifted towards the island with depth, being centered at station 7 below the lOO-decibar surface. The cross sections (fig. 2, panel B) show that it was still evident dovm to the 500- decibar surface at station 7. The most striking feature of the velocity field was the persistence of the surface velocities down to the 300-decibar surface in the southern part of the eddy. The velocities at the surface were almost uniform, except for slight maxima of about 0.8 knots (40 cm/sec) between stations 11 and 14. The velocities around the eddy decreased with depth, as expected, except in the vicinity of station 2, where velocities of 0.7 knot (35 cm/sec) were still indicated at the 300-decibar surface. Temperatures The temperature cross sections (fig. 4) were constructed from bathythermo- graph observations. The general distribution of temperature followed the pattern that was in- ferred from the geostrophic currents. I.e., the isotherms show doming in the center ^ In the northern hemisphere, flow which curves to the left (counterclock- wise), when facing downstream, is cyclonic, and flovj which curves to the right (clockwise) is anti-cyclonic (Holmboe et al. 1946, p. 191). A cyclonic eddy is characterized by a depression in the geopotential topography at its center, and an anti-cyclonic eddy by a doming. of the eddy (fig. 4, panels B and C). A strong northerly flow is indicated by the depth and sharpness of the thermocline along the southwest coast of Hawaii. The effects of diurnal heating were shown by the small pockets of warm water on the surface at stations 6, 10, and 14. In each case the BT lowerings were made during daylight and when the wind was Beaufort force 2 or less. In order to estimate the amplitude of internal waves that could be ex- pected in the area, the vessel was permitted to drift from 1930a December 12 to 1000& December 13 at approximately 19°41'i»-, 156°15'V«., while bathythermograph lowerings were made at half -hour intervals. As was expected (Sverdrup et al. 1946, p. 588), the results (fig. 5) show that the amplitude was greatest at the top of the thermocline and decreased rapidly with depth. The 75°F. isotherm, which was just below the thermocline, had a maximum change of depth of 115 feet, while the 60°F. isotherm had a change of only 80 feet. Although the data indicate the pre- sence of waves of several periods, the time covered by the observations was too brief to permit further analysis of the data. Sigma-t The distribution of sigma-t, as shown by the cross sections (fig. 6) and lateral surfaces (fig. 7) is consistent with the dynamic topography. The cyclonic nature of the eddy is shown by the doming of the isopleths in the vicinity of station 6. The topography of the 23.6, 24. 0, 25. 0, and 26.0 surfaces indicates that the source of most of the water in the eddy was from flow around the southern coast of Hawaii . Flow through Alenuihaha Channel is not indicated until the depth of the 25.0 and 26.0 surfaces is reached and then it is relatively weak. The 23.6 surface was selected for contouring because it was the greatest value that intersected the surface and therefore should illustrate the greatest depth from which nutrients could be brought to the surface by isentropic flow. However, since the difference in density is greater than the difference In temper- ature on the two sides of the eddy would indicate, it is probably Indicative of the degree of intrusion of less saline water that was being driven into the area around the southern tip of Hawaii by the southeasterly winds which predominated during the cruise period. Salinity The salinity cross sections (fig. 8), surface salinity (fig. 9), and plots of salinity on the sigma-t surfaces (fig. 7) show the degree of the intrusion of water from the southeast. The surface salinities show that water having a sa- linity of less than 35.0 °/oo had entered between stations 1 and 2 and had pene- trated three-quarters of the way around the eddy. Below the surface its progress is shown by the trough of low salinity on the 24. 0 sigma-t surface and by the tongue of low salinity water that had penetrated to station 9 on the 25.0 surface. Dissolved Oxygen The vertical distribution of dissolved oxygen (fig. 10) is very similar to that shown for 20°N. latitude in the Carnegie section (Sverdrup et al. 194t>, p. 710) except for the O2 maximum of greater than 5.0 ml/1. The Carnegie data show that this corresponds to the S °/oo maximum, and hence it can be attributed to con- tact with the atmosphere in the region northeast of the islands, where evaporation and cooling caused the surface waters to sink and spread out as an intermediate layer. In figure 10 it is present only as a small elongated cell at about 100 m, on an axis through stations 2 eind 15 and corresponds to the trough of low salinity which appeared on the 23.6 and 24. 0 slgma-t surfaces. 10 HUGH M. SMITH CRUISE 10 Cruise 10 of the Hufih U. Smith, July 19-31, 1951, was the first of a series of five cruises to investigate the general hydrographic conditions in the offshore waters of the Hawaiian Islands. Thirty-three stations were occupied at the positions shown in figure 11. Casts to 1,200 m. were made at all stations except 15, lb, 20, and 21, where casts were made to approximately 50 m. above the bottom. Stations 19 and 33 vvere occupied at approximately the same position. The data from the two were averaged in constructing the station plots, since both fitted into the time sequence when compared to adjacent stations. Stations 8A and 8 were also occupied at approximately the same position, but in this case the time Interval between 8 and all the surrounding stations was less than for 8A so only 8 was used. The solid lines on the station plot (fig. 11) indicate the lines along which profiles of dynamic height, temperature, sigma-t, salinity, and dissolved oxygen have been drawn. The order and method of presenting the data are the same as for cruise 1. General Wind Pattern The weather maps for the cruise period show the well-developed Eastern North Pacific High which is typical of summer conditions. However, comparison of the computed winds (table 4) with the average winds (table IJ shows that the forces were normal for July but that an abnormally large percentage of observed winds were from the east. The computed velocities vary from 9 to 20 knots, with 16 of the 23 values being within the 11-16 Jtnot range of the Beaufort 4 average for the month. Out of 23 observations, lb or 70 percent show east winds, although the normal for the month is only 30 percent. V»hen the wind directions were transformed into cur- rent direction by the 45° cum sole rule, they were 5° to 50° to the right of the 295°T mean for July (table 2). Dynamic Topography and Geostrophic Currents The dynamic height cross sections are shown in figure 12 and the dynamic topography of the upper 3OO decibars (m. ) in figure 13. Because of uncertainty as to the effect of land masses on the topography, no attempt was made to construct the topography Inshore of stations, except in areas where there were strong indica- tions that the flow should follow a definite pattern because of the physical con- figuration of the land masses and the circulation in the surrounding area. For example, the contours were drawn in the area south of Hawaii because the topography to the east and south indicates a strong flow parallel to the south coast of that island due to the divergent effect of the island barrier. In this and similar cases the contours are dotted. The topography shows that the circulation on the northeast or windward side and on the southwest or leeward side of the island chain is completely dif- ferent. On the windward side of the islands the circulation was quite confused (figs. 12 and I3). The flow was westerly all along the section from station 27 to station 30, with the highest velocities occurring between stations 27 and 28. The flow between stations 30 and 32 was easterly, but it turned again to the west north of station 32. In the area north of Oahu the flow was deflected northwest- ward along the islands. On the leeward side two large cyclonic eddies dominated the circulation pattern (figs. 12 and 13), one centered at station 23 and the other at station 10. The one west of Hawaii, centered at station 23, was much farther north than during cruise 1. The slopes of the surfaces in the eddy centered at station 10 were so great that it seems reasonable to assume that it was a case where external effects such as tides or internal waves were in phase witi; the effect of the horizontal motion. 11 Kauai Channel is the only channel for which there are sufficient data to attempt to contour the topography. The resulting flow pattern is very confused. The heights of the surfaces at station 8 indicate northerly or cloclcwise flow around the west coast of Gahu. On the Kauai side of the channel northerly flow is in- dicated by the 0-, 50-, and 100-decibar surfaces and westerly by the 200-declbar surface. Temperatures The temperature data are again based on the bathy thermograms. Figure 14 shows the temperature profiles for the five sections indicated on the track chart. Figure 15 is a plot of the depth of the 75°F. isotherm, which was drawn as an example of a rapid field method for obtaining the major features of the circulation pattern. ever most of the area the basic configurations of the temperature field followed the pattern expected from the geostrophic flow. For example, both the cross sections and the plot of the dep*-,h of the 75^. isotherm show a doming of the subsurface isotherms at stations 10 and 23. The temperature field in Kauai ChaLnel differed in some respects from that expected from the geostrophic currents. At station 3, where the isotherms dome, there was mixing, caused by divergence or wind stirring, strong enough to lower the surface temperature. The plot of the 75°F. isotherm indicates that it was part of a cold dome extending northeastward to the area between stations 6 and 7. The cyclonic circulation required to produce this condition agrees with the northerly geostrophic currents at the surface on the Gahu side of the channel but not with those on the Kauai side. As a result of summer heating, the temperature of the surface layers in the area west of Hawaii were at least 1° to 2°r. higher than those of cruise 1. The effects of local heating are shown in the cross sections by the small cells of water at the surface having a temperature higher than 79°F. 31gffla-t The effect of summer heating on the density is shown on the cross sec- tions by the lower density of the approximate boundary between the quasi-homogeneous surface layer and the well-defined density gradient. At the time of the winter cruise (cruise 1) the boundary was the 23.8 surface, but on this cruise it was only the 23.2 surface. In the surface layers (fig. 17), two features stand out in the complicated circulation pattern. The first is the band of surface water with sigma-t greater than 23.0 on the northeast side of the islands. It was not related to the current pattern but was a combination of the high salinity around station 31 and the low temperatures along the islands (bucket and reversing thermometer temperatures). The second was the low values, as low as 22. b5 which occurred over the surface of the eddy west of Hawaii. They were due to high surface temperatures which per- sisted in spite of the force 5 winds reported in the bathythermograph log. The horizontal plots of depth of sigma-t surfaces (fig. 18) have the topo- graphy indicated by the geostrophic currents. They are included only for the detail they add in the area north of the middle group of islands. The 25. 0 and 26.0 con- tours show that the incident currents separated north of Molokai, one branch turning northwest along the islands, and the other turning cyclonically away from the is- lands, thus completing the pattern shown by the geostrophic currents. 12 Salinity The salinity cross sections (fig. 19) show a maximum greater than 35 /oo just below the quasi-homogeneous surface layer at all stations except 22. However, the Hansen bottle spacing was such that this layer was missed in the sampling at a large number of stations, so it was largely constructed by reference to the T-3 diagrams of the adjoining stations. The thickness of the layer was greatest in the western section (fig. 19, panel A), where the > 35.0 °/oo band was 100 m. or more in thickness. The surface salinity (fig. 20) reflects the extent of the sub-surface maximum by sharp increases in the west and northwest sectors. Over the rest of the area it is almost uniform (34.6 - 34.7 °/oo), except for the area around the middle islands, where a cell of less than 34.6 °/oo occurred, and around stations 10 and 31, where it increased sharply. The minimum could only have been caused by runoff from the islands. The maxima were in areas of strong cyclonic motion and could have been caused by divergence. Dissolved Oxygen The vertical distribution of dissolved oxygen (fig. 21) was typical of the North Pacific at these latitudes. It had a maximuxa of more than 5.0 g/1 just below the level of the well-defined density gradient and a deep minimum of 0.6 - 1.0 ml/1 at the 500-800 m. level. The maximum is attributed to contact with the surface at the subtropical convergence during the period when evaporation increased the salinity. Although the minimum is frequently attributed to lack of replenish- ment by horizontal flow, its origin is not completely understood. HUGH M. oMITH CfiUISi:; 12 Cruise 12 of the Hufih M. Smith was made to observe the hydrographic condi- tions in the offshore waters of the Hawaiian Islands during the period when the local skipjack fishery was undergoing its fall decline. The station coverage (fig. 22) was similar to cruise 10, but a number of changes were made in the observational program. Dissolved oxygen analyses were omitted and inorganic phosphate analyses were included. The geomagnetic electrokinetograph, which had been installed just before this cruise, was used to make current observations at each station and mid- way between stations. The stations north of Hawaii, 31 to 32 of cruise 10 (fig. llh were omitted to permit further study of the eddj indicated in the vicinity of sta- tion 1 by the G£K data. The order and method of presenting the data are the same as for cruises 1 and 10. General Vjind Pattern The winds during the cruise period (table 5) were of about normal force for October, but they were more southeasterly than normal. From October 13 to 26 they were part of the circulation around the Eastern I»orth Pacific High, but a greater percentage than normal were from the east and southeast. Therefore, the currents inferred by the 45° cum sole rule are 15° to 55° to the right of the 280°T mean for October. A shift of the currents even further to the right may be in- ferred after October 27, when the wind shifted to the south as a low moved into the area from the west. Dynamic Topot-'.raj'hy and Geostrophic Currents The dynamic heights (fig. 23) showed less variation than those of cruise 10 and consequently the geostrophic currents (fig. 24) were shallower and weaker. Significant velocities of 10 cm/sec (0.2 kt.) or greater were limited to depths of 13 300 m. or less, and at that level velocities of this magnitude were found only between stations 29 and 30. In contrast, during; cruise 10 velocities of over 20 cm/sec (0.4 kt.) were found on the 300-decibar surface. On the windward side of the islands the dynamic topography contours are Incomplete because of the omission of the stations north of Hawaii. The flow normal to the section east of Hawaii was confused in the upper 150 m. by the east- erly flow indicated between stations 28 and 29. North of Oahu the flow was again northerly, indicating that the major portion of the flow was being deflected by the middle group of islands. To the leeward of the islands the most prominent features were again the two cyclonic eddies. The one west of Hawaii was larger in diameter, but did not have velocities as great as the corresponding eddy of cruise 10. The eddy south of Oahu was centered off station 1. It was also relatively weak, having a maximum velocity of only 30 cm/sec {0.6 kt.) as against the 72 cm/sec (1.4 kt.) maximum of cruise 10. In Kauai Channel northerly flow was indicated in the upper 100 m. It was again the result of the high values at station 8, which were indicative of a clock- wise flow around Oahu. GEK Currents The current vectors computed from GSK observations are shown in figure 25. They represent POFI's first attempt at direct current measurements in the Hawaiian area. The results are only partially satisfactory, if the surface geostrophic currents are used as the standard. They agree fairly well in direction and magni- tude in the offshore areas where the velocities were large, such as in the leeward eddies, but in the vicinity of station 8, just west of Cahu, the G3K currents were southerly and the geostrophic northerly. As mentioned above, the accuracy of the latter are also open to doubt in inshore areas, but it is doubtful if the error could be over 90°, as the GEK currents would indicate. The persistence of the eddy around station 1, shown by the "recheck" of the area, was the most interesting information provided by the G£K. In spite of time differences of up to 7 days and a shift of the incident winds from east to south, the observations made on the second coverage of the area (those marked "A" in fig. 25) agree almost perfectly with those made on the first. Temperatures Again the temperature field (figs. 26 and 27) was simply a reflection of the distribution of mass associated with the circulation pattern shown by the geo- strophic currents. Divergence and/or wind-mixing in the eddy west of Hawaii was shown by the 2°F. drop in surface temperature at its center. Sigma-t The sigma-t distribution (figs. 28 and 29) differs only slightly from that of cruise 10. On the windward side, east of stations 17 and 18, the 23.2 sigma-t surface is still the upper limit of the well-defined density gradient, but over the rest of the area it is the 23.0 surface. The difference was caused by slightly lower surface temperatures in the southeastern sector of the windward side. This difference could be attributed directly to mixing or "upwelling" only in the area around station 19, where' the 23. 0 sigma-t isopleth reached the surface and surface salinity was slightly greater than in the surrounding area. The horizontal plots of depth of sigma-t surfaces are again included for the information which the 25.0 and 26.0 surfaces add to the description of the cir- culation north of the middle group of islands. The cells of greater than 200 m. in 14 the 25.0 surface and of greater than 320 m. in the 26. G surface are indicative of anti-cyclonic flow due to the deflective effect of the islands. In both cases the centers of the cells were closer to the islands than during cruise 10. Salinity A cell of high-salinity water in the well-defined density gradient was again the most prominent feature of the salinity cross sections (fig. 30). The upper 35.0 °/oo isohaline, which approximated its upper limit over the entire area except east and south of Hawaii and at stations 2 and I4, coincided approximately with the 24.0 sigma-t surface. In the area east of Hawaii the salinity maximum was between 34.8 and 35.0 °/oo, indicating that water of lower salinity was moving into the area. The station plots indicate that it penetrated at least as far as station 26. The surface salinities (fig. 31) were 0.1 to 0.2 °/oo higher than on cruise 10 except in the channel between Maui and Lanai , where a small cell of low- salinity water again indicated runoff, and in the section east of Hawaii, where the pattern was as confused as, and probably the result of, the current pattern (fig. 24). At station 29 there was a cell of low-salinity water at the surface which be- cause of the easterly flow indicated by the geostrophic currents could be ascribed to the runoff from the windv/ard coast of Hawaii. At the adjoining station (28) the cell with salinity greater than 34.8 °/oo broke the surface. Considered in conjunc- tion with the dome in the 78.0°F. isotherm, this would indicate divergence in spite of the "high" in the dynamic topography. Inorganic Phosphate In the surface layers of the ocean there is a continual loss of the dis- solved nutrient salts from the euphotic^ b^'cause of the production of organic mate- rial and a general downward movement of the particulate matter thus formed. In the open ocean the only processes by which nutrients can be returned to the surface layers are vertical diffusion, convective overturn, and divergence (upwelling). To determine whether mixing or divergence of sufficient magnitude to cause enrichment of the surface layers was induced by the complex flow around the islands, inorganic phosphate analyses were made during cruise 12. Phosphate analyses were made be- cause they are more adaptable to shipboard work than those for nitrate, the other major dissolved nutrient salt. Only the cross sections of inorganic phosphate (fig. 32) are included, since they are adequate to depict the variations. The 0.6-(ig atoms/1 isopleth formed the upper boundary of the well-defined gradient. It was between the 24.8 and 25.2 sigma-t surfaces and at a depth of I50 ra. or greater, except at station 5, where it was at only 52 m. Although the 0.4-|jig atoms/1 surface has been drawn in, the distribution above the 0.6-^ig atoms/1 level was very irregular and bore little resemblance to the other features. This was probably because the lower limit of the accuracy of the method of analysis was being approached (v.ooster and Rakestraw 1951). DI3GUS3I0K The marked similarities of the circulation patterns of the three cruises have been pointed out repeatedly in the discussion of the results. These quasi- permanent features are more understandable if the nature of the island barrier aind the incident currents are explained and their interaction discussed piecemeal. The first impression given by the chart of the windward or high islands of the Hawaiian Archipelago is of a series of vertical obstacles lying in a south- east to northwest direction. However, when a cross section of the islands is con- structed (fig. 33), they are seen to resemble a solid barrier having four small 15 openings. Cnly two of these openings, Kauai Channel between Oahu and Kauai, and Alenuihaha Channel between Hawaii and Maui, extend belovv the 1,000-m. depth that has been assumed as the level of no motion in the computation of dynamic heights. The third, Kaiwi Channel between Molokai and Oahu, has a sill depth of only 614 m. (336 fathoms). The fourth, between Molokai and Maui, is almost negligible; it is split by Lanai Island and has a sill depth of only 80 m. (44 fathoms) and a width of only 8 miles. Sverdrup (1946, p. 723) states that "a clockwise rotating gyral is pre- sent in the eastern North Pacific with its center to the northeast of the Hawaiiein Islands. It is probable that the location of this gyral changes with the seasons and shifts from year to year, so that occasionally the gyral may lie entirely to the northeast of the Hawaiian Islands, whereas in other circumstances the Hawaiian Islands may lie inside the gyral." This implies that the flow incident to the is- lands is either toward the west or slightly northwest. It may be further assumed that it is continually fluctuating, since the Eastern North Pacific High, which provides the driving force, varies constantly in intensity and position. Further evidence of the seasonal variation in the incident currents and the variations in the incident currents which might be expected during a single month is shown by the charts of mean wind and mean currents (summarized in tables 1 and 2) for the area east of Hawaii. The average monthly current directions, which were taken from the Pilot Charts, illustrate the annual cycle. The most northerly average direction, 310°T, occurs in January, when the greatest percentage, 42 per- cent, of easterly winds was reported. The most westerly direction (260 T) occurs in September. This is also the period when the Eastern North Pacific High starts to decline in intensity, and this could account for the relatively weak flow of cruise 12. The greatest variation of both winds and currents occurs during the November to March period, when the Eastern North Pacific High is least developed. It is during this period that low pressure cells, such as those that were present during cruises 1 and 12, move into the island area bringing the "kona"2/ storms (Simpson 1952) . When the nature of the island profile and the westerly flow are consid- ered, the quasi-permanent features can be ascribed to (1) a stream flow impinging upon a lamina at a shallow angle, (2) flow around a single barrier (Long 1952), (3) a jet or wake stream discharged into a fluid at rest (Rossby 1936), or (4) a combination of (2) and (3). Although there was some flow through the channels, the middle group of islands (Cahu-Maui) seemed very much like a solid barrier, so that the circulation to the east resembled in many respects a "stream flow on a lamina" (Lamb 1932). In such a case, the flow is split by the barrier; the point of separation and the amount going in either direction are dependent upon the angle of impact. The in- cident flow of both cruises 10 and 12 was from an easterly direction, so that the major part of the flow was deflected to the right or northwest and only a small part to the left or southeast. The easterly flow southeast of station 32 during cruise 10 was the result of the segment of the incident current that was deflected to the left. The angle of deflection or degree of anti-cyclonic motion imparted' to the segment of the incident current that was deflected to the right controlled the flow through Kauai Channel during cruises 10 and 12. During cruise 12, when the geo- strophic currents north of Oahu had a strong northerly component, the flow was northerly through the channel. During cruise 10, when the angle of deflection was small at the surface and decreased still further with depth, the flow was across the channel above the 200-decibar surface, where a slight westerly flow was in- dicated. 2/ Kona. a Polynesian adjective meaning "leeward," is used locally to describe periods during which the usually persistent tradewinds are replaced by southerly winds and rain squalls. Each year the drier leeward sides of the Hawaiian Islands receive more than half of their rainfall from two or three of these storms. 16 In the lee of the islands there was a striking resemblance between many of the features of the flow pattern and the "east wind case" described by Long (1952) in his discussion of the results of model studies of flow past a barrier in a rotating spherical shell. This was particularly noticeable in the results of cruise 1, which had the stations most closely spaced and a series close inshore. Cn the equatorward side Lon^; found that the fluid in the immediate vicinity of the barrier curved northward along the obstacle for about a quadrant (90°) while the bulk of the fluid continued in a general westerly direction. This phenomenon could account for the strong northerly flow along Hawaii during cruise 1 and the greater dynamic height at station 8 during both cruises IC and 12. ^ong the boundary between the bulk of the fluid that was continuing westward and the wake of the barrier he found a series of horizontal clockwise eddies having their axes directed easterly. Ke attached no significance to their direction and doubted that they could exist in a stratified fluid such as the ocean. However, it is felt that the persistence of the easterly flow down to the 300-decibar surface on cruise 1 is a manifestation of this phenomenon. On the poleward side he found that the flow separated from the barrier and moved zonally to form a series of cyclonic eddies. This would suggest that the eddies found in the survey area are merely the first of a series that occur down- stream from the islands. However, it must be remembered that only part of the In- cident flow passes through the channels, so that a complete analogy to the single barrier case is not valid. It has been demonstrated that a similar series of eddies v;ould result from the flow through the channels. Rossby (1936) showed in his Vvake Jtresun Theory that as a jet or wake, which has been discharged into a fluid at rest, ^^asses down- stream it acts as a series of sinks with respect to the surrounding fluid. Large quantities of fluid are removed from the surroundings, and this removal is associ- ated with the creation of a countercurrent along the left side. The mass transport increases duvjnstream, but is intermittently reduced through the discharge of eddies along the boundary of the currents. On the right side a compensation is set up which decreases in intensity and becomes negligible. Thus, the eddy west of Kawaii can be attributed to the flow through Alenuihaha Channel and the one west of Oahu to the flovv tl_rough Kauai Channel, ^^gain aiinur discrepancies between the selected model and prototype are evident. In the first case it has already been shovvn that durir.g cruise 1 part of the flow was the result of the clock-wise flow around the island of Kavjaii. In the second case the magnitude and strength of the eddy, par- ticularly during cruise 10, seemed iLirger than could be expected from such a limited source as Kaiwi Channel. The variations in strength, magnitude, and position of the eddies during the three cruises reflect the varying direction and strength of the incident cur- rents which were inferred from the monthly wind and current data. However, the stability of the eddy south of Oahu, as shown by GiUi observations made as much as 1 week apart and after a 90° shift in the incident winds, indicates that these changes must occur very gradually. When the sigma-t cress sections are compared to the inorganic phosphate cross sections of cruise 12 (fig. 32) to determine whether enrichment of the sur- face layers by lateral mixing (along sigma-t surfaces) occurred in the eddies or in any other areas, the results are insignificant compared to those reported for equatorial waters by Cromwell (1951) and Austin (1954). The greatest depth from which nutrients could have reached the surface by lateral mixing during any of the cruises was about 100 m., i.e., at stations 12 and I4 during cruise 1 (fig. 6, panels C and D) or at stations 1 and 25 during cruise 10 (fig. 16, panels A and D) . Such mixing could not have produced much enrichment, because the phosphate-rich layer was below 150-200 m. during cruise 12. The great depth of the phosphate-poor layer in the Hawaiian Island area can be explained by the circulation which produced the high-salinity water that lies at its lower limit. This layer is the result of subsidence and spreading out of water which has had its density increased by evaporation and cooling as it moved 17 around the Northeast Pacific Gyral. Sverdrui; (:.946, fig. 209A) , indicated that the source of this water is at about 40'-^., 140°W. This results in a sub-surface re- circulation over the area of water that is already low in inorganic phosphate. The acceleration of the natural tendency for organic phosphate to settle out as partic- ulate matter by the downward motion in the area of subsidence would also contribute to the barrenness of the recirculating water. The only perceptible evidence that enough mixing to enrich the surface layers is induced by the impingement of the west to northwesterly currents on the islands was shown in the analyses of zooplankton abundance by King and Hida (1954). They found that although the abundance of zooplankton was almost uniform throughout the region, the upstream area to the south and east of the island of Hawaii yielded, on the average, the lowest volumes (cruises 10 and 12, stations 26 to 30). A com- parison of the plots of the abundance of zooplankton (King and Hida 1954, fig. 10) with the lateral plots of geostrophic currents for cruises 10 and 12 (figs. 13 and 24) indicates that there were slight maxima at, or near, the cyclonic eddies in the lee of the islands during both cruises and at station 3I during cruise 10. However, two other maxima occurred that could not be attributed to, nor remotely connected with, any unusual hydrographic features, the first at station 5 during cruise 10 and the second at station 6 during cruise 12. The first was particularly interest- ing since it was 21 ml/l,000m3 higher than or 1.5 times that of any other station, and it occurred at the same station as the inexplicable high inorganic phosphate content in the upper 100 m. during cruise 12. The writer believes that the occurrence of the zooplankton maxima at or near the centers of the cyclonic eddies and the frequent occurrence of high salin- ities and low temperatures at their centers are the result of divergent motion which causes some enrichment of the surface water. The slightness of the maxima and the number of exceptions to the increase of salinity and decrease of tempera- ture at the centers indicate that vertical motion is small and intermittent at best. Acknowledgements The data embodied in this report represent the combined efforts of a large number of the staff of tOU. Hov«ever, special acknowledgement should be made to M. B. Schaefer, cruise 1 field party chief, J. '£. King, cruise 10 field party chief, H. J. Mann, cruise 12 field party chief, and to Mary Lynne Godfrey, who pro- cessed or supervised the processing of most of the data. T. 3. Austin and G. R. Seckel made helpful suggestions and assisted generously in the preparation of the final report. The figures were drawn by Tamotsu Nakata. 18 Literature Cited AUSTIN, THCM/lS S. 1954. Uid-Facific oceanography III, transequatorial waters, August-October 1951. U. 6. Fish and t.ildlife Service, Spec. Sci. Rep.: Fish. No. I3I, 51 p., 13 figs. CRCMWELL, TOV.TJSEND 1951. Mid-Pacific oceanography, January-March I95O. U. S. Fish and Wildlife Service, Spec. Sci. Rep.: Fish. No. 54, 76 p., 17 figs. 1954. Mid-Facific oceanography II, transequatorial waters, June-August 1950, January-Karch 1951. U. S. Fish and Wildlife Service, Spec. Sci. Rep.: Fish. No. 131, 180 p., 32 figs. DEFANT, ALBERT 1950. Reality and illusion in oceanographic surveys. Jour, of Mar. Res., vol. IX, No. 2, pp. 120-138, 10 figs. HCLMBCE, JORGEH, W. GU3TIN, and G. E. FORoYTHE 1945. Dynamic meteorology. 378 p., New York: John Wiley and Sons, Inc. KING, JOSEPH E., and T. S. KIDA 1954, Variation in zooplankton abundance in Hawaiian waters, 1950-52. U. S. Fish and Wildlife Service, Spec. Sci. Rep.: Fish. No. 118, 66 p., 16 figs. LA FOND, EUGENE C. 1951. Processing oceanographic data. U. S. Kavy Hydrographic Office Publica- tion No. 614, 114 P- LAMB, HORACE 1932. Hydrodynamics. 6th ed., New York, Cambridge University Press, 729 p. LONG, ROBERT R. 1952. The flow of a fluid past a barrier in a rotating spherical shell. Jour, of Meteorology, vol. 9, No. 3, pp. 187-199, 18 figs. MCNTGCtSRY, R. B. 1954. Analysis of a Hu.aih M. Smith oceanographic section from Honolulu south- ward across the Equator. Jour, of Mar. Res., vol. I3, No. 1, pp. 67- 75, 6 figs. PARR, A. E. 1936. On the relationship between dynamic topography and direction of current under the influence of external (climatic) factors. Journal du Conseil, vol. XI, No. 3, pp. 299-313, 3 figs. R03SBY, C. G. 1936. Dynamics of steady ocean currents In the light of experimental fluid mechanics. Papers in Physical Oceanography and Meteorology, vol. V, No. 1, 43 p. , 26 figs. 19 SEI\^KLL, H. R. 1937» Short period vertical oscillations in the western basin of the North Atlantic. Papers in Physical Oceanography and Meteorology, vol. 5, No. 2, 44 p. , 9 figs. 3STTB, C. E., and STAFF OF POFI 1954. Progress in Pacific Oceanic Fishery Investigations 1950-53. U. S. Fish and Vi'ildlife Service, Spec. Sci. Rep.: Fish. No. Ufa, 75 p., 29 figs. SIMPSON, R. H. 1952. Evolution of the Kona storm, a subtropical cyclone. Jour, of Meteor- ology, vol. 9, No. 1, pp. 24-35, 25 figs. STRCUP, E. D. 1954. Mid-Pacific oceanography IV, transequatorial waters, January -March 1952. U. S. Fish and Uildlife Service, Spec. Sci. Rep.: Fish. No. I35, 52 p., 18 figs. SVSRDRUP, H. U., M. V.'. JOHNSON, and R. K. FLmnNG 1942. The oceans, their physics, chemistry, and general biology. New York, Prentice-Hall, Inc., 1087 p. U. S. NAVY HYDROGRAPHIC OFFICE , V/ind, waves, and swell, principles of forecasting. Miscellaneous pub- lication 11275, 61 p., 12 figs. 1946. Current atlas of the northeast Pacific. H. C. No. 540, 12 charts. VON ARX, WILLIAM 3. 1950. An electromagnetic method for measuring the velocities of ocean cur- rents from a ship under way. Papers in Physical Oceanography and Meteorology, vol. XI, No. 3> 62 p., 17 figs. WOOSTER, WARREN S., and N. 'ii. RAKESTRArt 1951. The estimation of dissolved phosphate in sea water. Jour, of Mar. Res., vol. X, No. 1, pp. 91-100, 5 figs. 20 riGUiSS Frontispiece: The Windward or High Islands of the Hawaiian Archipelago. Hufih M. Smith Cruise 1 1. Station positions. 2. Profiles of isobaric surfaces relative to the 1,000 decibar surface. 3. Geopotential topography of 0, 50, 100, 200, and 300 decibar surface. k. Temperature profiles. 5. Variation in depth of the 75°, 70°, 65°, and 60°F. isotherms with time. 6. 3igma-t profiles. ?. Topography of the 23.6, 24.0, 25.0, and 26.0 sigma-t surfaces and salinity on these surfaces. 8. Salinity profiles. 9. Salinity at the sea surface. 10. Dissolved oxygen profiles. Hugh M. Smith Cruise 10 11. Station positions. 12. Profiles of the isobaric surfaces relative to the 1,000 decibar surface. 13. Geopotential topography of the 0, 50, 100, 200, and 300 decibar surfaces. 14. Temperature profiles. 15. Topography of the 75°?. isotherm. 16. Sigma-t profiles. 17. Sigma-t at the sea surface. 18. Topography of the 23.2, 24. 0, 25. 0, and 2fa.O sigma-t surfaces. 19. Salinity profiles. 20. Salinity at the sea surface. 21. Dissolved oxygen profiles. Hugh M. Smith Cruise 12 22. Station positions. 23. Profiles of the isobaric surfaces relative to the 1,000 decibar surface. 24. Geopotential topography of the 0, 50, 100, and 200 decibar surfaces. 25. Current vectors computed from GEK measurements. 21 26. Temperature profiles. 27. Topography of the 75°F. isotherm. 28. Sigma-t profiles. 29. Topography of the 23.2, 24.0, 25.0, and 26.0 sigma-t surfaces. 30. Salinity profiles. 31. Salinity at the sea surface. 32. Inorganic phosphate profiles. Miscellaneous 33 • Profile of the Hav.aiian Islands, Kauai to Hawaii. 22 Fig. 1 H. M. Smith cruise 1, December 13-21, 1949, station positions. Solid lines indicate lines along which profiles of dynamic heights (dyn. M), temperature (°F), sigma-t, salinity (°/oo), and dissolved oxygen (ml/1) have been drawn. 23 o < 2.0 1-8 1,6 1.4 1.2 1.0 .8 .6 .4 .2 0 Fig. 2... the 1, 9-12. 1 - ODB^^^^^ - 50-^.,^^_^_^^ - IOO--..,.^__^___^ - 150 _____ 200 •——___ 1 1 ' """^^ - — - vin.. — 400 500 — ___ TOO — 1 ~ 13 14 15 16 1 1 ODB — _ 50- - 100 - ■ — 200 - 300 • — 400 . 500 ■ 7nn . 1 1 (C) •H. M. Smith cruise 2 000 db surface and D. Stations 11-16. (D) Profiles of isobaric surfaces relative to A. Stations 1-4, B. Stations 5-8, C. Stations 24 155° III Ill I KNOTS 0 I 2 I I I I I I I I I I I I I I I I I M I I CM SEC. 0 50 100 M. Smith cruise 1. pography (dyn. M) relative to the 1,000 db. surface, contour inter- val 0.02 dyn. M. Arrows indicate direction of flow. A. 0 db. , B. 50 db. , C. 100 db. , D. 200 db. , and E. 300 db. surfaces. 25 O 0 -I -I 78 76 4 3 2 1 i 1 1 1 liJ a. LlJ o 5 6 7 8 1 1 1 - ■ 13 14 15 16 _ 'y 1 -^ - Fig. 4. -H. M. Smith cruise 1. Surface and vertical temperature pro- files. Upper panels - surface temperatures (°F) from "bucket" ther- mometer reading at eachbathythermograph lowering. Lower panels - temperature profile based on bathythernnograph lowerings, isotherm interval 1°F, depth of lowering shown by small horizontal dashed line. A. Stations 1-3, B. Stations 5-8, C. Stations 9-12, and D. Stations 13-16. 26 o DEPTH (FEET) ui ^ o o o o SURFACE TEMP °F n — I — r _L J 1 L Fig. 5. --H. M. Smith cruise 1. Upper panel - variation of the surface temperature with time, Lower~panei - variation in depth of isotherms with time from bathythermograph lowerings made December 13, 1949 while drifting from 19°41'N.. 156°15'W. to 19°43'N.. 156°20'W. 27 Fig. 6. — H. M. Smith cruise 1. Profiles of sigma-t, isopleth interval 0.2. A. Stations 1-4, B. Stations 5-8, C. Stations 9-12, and D. Sta- tions 13-16. 28 155° Fig. 7. — H. M. Smith cruise 1. Solid lines, topography of 23. 6, 24.0, 25.0, and 26.0 sigma-t surfaces, contour interval 20 M. Dotted lines, salinity on the sigma-t surfaces, isohaline interval 0.1 °/oo. A. 23.6, B. 24.0, C. 25.0, and D. 26.0 signna-t surfaces. 29 0 100 4 3 2 1 — • • 1 ! 34.61 ^ 34348~ 200 300 400 350-^, 34.8 / (23-46 V (E 1— ^ /' ^344"" • 04.6 ^ LlJ X 1- Q • <34 2 • • 500 p.nn 34.2 -^__ • V. Fig. 8, — JH. M. Smith cruise 1, Profiles of salinity in°/oo, isohaline interval O.T^/oo. A. Stations 1-4, B. Stations 5-8, C. Stations 9- 12, and D. Stations 13-16. 30 Fig. 9.--H. M. Smith cruise 1. Sxir- face salinity in *'/oo, is ohaline in- terval 0.2 o/oo. 31 100 — 200 a: UJ 5 300 Q. Q 400 500 600 100 - ~ 200 I- UJ CL UJ Q 300 - 400 500 - 600 G° • • • • ^50 • 4.5 ^"^^ -^ • • 40* 3 5* — -^ - _ • ^^ ^ " — — 30^/ ^^-T~^ ^^^^7^— • 2^^/ /--^ \^^^ — 20'-^ / \v.^^^^ \'b'^ ^10^ \ • (C) Fig. 10. --H. M. Smith cruise 1, Profiles of dissolved oxygen in ml/1, isopleth interval 0.5 ml/1. A. Stations 1-4, B, Stations 5-8, C. Sta- tions 9-12, and D. Stations 11-16. 32 23° 22° 21' 20° IS- IS" 160° 159° t5 • 3 158° t6 10 157° 156° 18 • 17 I9t33 155° 425 • 32 • 26 31 154° 30 ..29 28 27 23° 22° 21' 20° 19= 18' 160° 159° 158° 157° 156° 155° 154° Fig. 11. --H. M. Smith cruise 10, July 19-31, 1951, station positions. Solid lines indicate lines along which profiles of dynamic heights (dyn. M), BT temperatures {°F), sigma-t, salinity (°/oo), and dissolved oxygen (ml/1) have been drawn. 33 Fig. 12.--2i._M- Smith cruise 10, Profiles of the isobaric surfaces relative to the 1,000 db. surface. A. Stations 1-5, B. Stations 6- 10, C. Stations 11-18, D. Stations 22 - 25, and E. Stations 27 - 30, 34 • - H. M. Smith cruise 10. Topography (dyn. M) relative to the 1,000 db. surface, contour in- terval 0. 04 dyn. M. Arrows in- dicate direction of flow. A. 0 db. , B. 50 db., C. 100 db., D. 200 db. , and E, 300 db. surfaces. 35 2 3 4 5 10 9 8 7 6 1 1 1 1 - "^ UJu. Oo CrtH 1 1 12 13 14 15 16 17 18 80 - I --" 1 1 1 1 1 /8 25 24 23 22 21 20 19 1 1 1 1 1 1 1 _ / "^"^ 27 28 29 30 80 78 - 1 1 1 CL Q Fig. 14. — H. M. Smith cruise 10. Surface temperature and vertical temperature profiles. Upper pan- el - surface temperature in °F from "bucket" thermometer readings at each bathythermograph lowering. Lower panel - tenaperature pro- files based on the bathythermo- graph lowerings, isotherm interval 1°F, depth of lowering shown by small horizontal dashed line. A. Stations 1-5, B. Stations 6-10, C. Stations 11-18, D. Stations 19-25, and E. Stations 27-30. 36 160' 154° Fig, l^.--ii. M. Smith cruise 10. Topography in feet of the 75°F isotherm, contour interval 50 feet. 37 10 9 8 7 6 '• J-^-- ^^"--^ * 100 ■^^^ '^iii'-aa ^^5 Ii:;;;:;;;^-24 w 200 - •^^^ . r25- UJ >^26- LlJ • ^"-^ 5 300 I 1- \^__ CL Q 400 X; 500 - • . fion ^^^ 27 Fig. 16.--_H._M. Smith cruise 10. Profiles of sigma-t, isopleth in- terval 0.2. A. Stations 1-5, B. Stations 6-10, C. Stations 11-18, D. Stations 25 - 26, and E. Sta- tions 27-30. (E) 38 160' Fig. 17. --_H. M. Smith cruise 10. Surface sigma-t, isopleth inter- val 0.2. 39 160° 159° 158° 157° 156° 155° 154 159° 158° 157° 156° 155° 154° 23' -22" . -^^^ -200 "-, ,^/,40^ L/" 180 -20C 20° 21' 280 300 280/ / / . 260^„„ -, , ^ y ^80 —280 .^260 240 Fig. 18.--H. M, Smith cruise 10, Topography in meters of 23. 2, 24.0, 25.0, and 26,0 sigma-t surfaces. Contour interval 20.0 meters. A. 23.2, B. 24.0, C. 25,0, and D. 26, 0 sigma-t surfaces. AO 100 ^ 200 h UJ 300 - 0. Ul Q 400 500 - 600 * i\ ; . <34 6" \ ' * ==346 ~~~-34a_ ^350 >35.0 .\^_^ '^350_ =348 "~~^344 \C"~----- ■"- , ^^^^^^ .^^ ^.34 2- ^ <34,2 ) j . \^^342 <34 2 \ >342 \ 344 x,^ Fig. 19. --_H; M_- Smith cruiae 10. Profiles of salinity in °/oo, iso- haline interval 0.2 °/oo. A. Sta- tions 1-5, B. Stations 6-10, C. Stations 11-18, D. Stations 19-25, and E. Stations 27-30. (E) a 160° 34 7 159° 158° 157 Fig, 20.-- H. M, /'/, ^?^- ' ; (^349 ^ 348 — J47 23° 22° 21° 20° 19° 18° 156° 155° 154° Smith cruise 10. Surface salinity in °/oo, isohaline interval 0. 1 /oo. 42 t/5 X (- Q. UJ Q 0 1 2 3 4 5 • • ino - — -"^ >5.0 -—•50 ^50 - "^"^ 200 ~ • \ '45 ~ 300 \ \.- — ^ • 400 \ :^ ^._^ ^•40 >35 " 500 \ \ -^'^ ^30 .25 — 20 ^ 1 5 ~ 10 9 8 7 6 (A) 24 23 22 21 20 19 X t- Q. LU Q 200 300 - 400 500 600 s X I- Q. LU Q 100 200 300 - 400 500 600 Fig. 21. — H. _M. Smith cruise 10. Profiles of dissolved oxygen in m/l, isopleth interval 0.5 ml/1. A. Stations 1-5, B. Stations 6-10, C. Stations 11-18, D. Stations 19- 25, and E. Stations 27-30. 43 Fig. 22.-- H,JM, Smith cruise 12, October 23 to November 2, 1951, station positions. Solid lines indicate lines along which profiles of dynamic heights (dyn. M), BT temperatures (°F) , sigma-t, salinity ( /oo), and inorgajiic phosphate (p.g at/1) have been drawn. 44 C/) ir LiJ I- iij o Q 2,0 18 1.6 14 12 10 8 6 4 ,2 0 700- 200- 300 — 400 — 500 — 700 (A) 20 11 12 13 14 15 16 17 18 0-— 18 - ^^ - if) (E 1 6 14 - ^ -- ^ ■ 50 -• 100 — ■ H LlJ 5 o 12 10 .^ I50-— 200-— 2 < >- 8 6 - -^ ■ 1 1 1 8 8 8 to ^ in Q 4 - 700' ■ 2 — • Fig. 23.--J4. M. Smith cruise 12. Profiles of isobaric surfaces re- lative to the 1,000 db. surface. A. Stations 1-5, B. Stations 6-10, C. Stations 11-18, D. Stations 22- 25, and E. Stations 27-30. 45 z ° I I I I I I I I I I I I I KNOTS 0 I 2 III I I I I I CM. SEC. 0 50 100 Fig. 24, --H. M. Smith cruise 12. Topography (dyn. M) relative to the 1,000 db. surface, contour interval 0.04 dyn. M. Arrows indicate direction of flow. A. 0 db. , B. 50 db., C. 100 db. , and D. 200 db. surfaces. 46 160 23° 22° 20° - 18° 160° Fig. 25. --H. M. Smith cruise 12. Current vectors computed from GEK measurements, veloc- ities in cnn/sec. "a" indicates observations made during the recheck of the area south of Oahu at the end of the cruise. 47 vJ o en 1 2 3 4 5 80 ' — i-'^ ^- ■ \ 1 1 - 78 - - 10 9 8 7 6 Ld Q- Q H 11 12 13 14 15 16 17 18 80 78 1 1 1 1 1 1 1 1 Q. Q 25 24 23 22 21 20 19 - "^ y N 1 1 -- 1 — - 27 28 29 30 80 1 1 ' ' - 78 - " "^-- — - I I- Q. U Q Fig. 26. --H. M. Smith cruise 12. Sur- face and vertical temperature pro- files. Upper panels - surface temper- ature (°F) from "bucket" thermometer readings at each bathythernnograph lowering. Lower panel - temperature profiles based on bathythermograph lowerings, isotherm interval 1°F, depth of lowering shown by small ho- rizontal dashed line. A. Stations 1-5, B. Stations 6-10, C. Stations 10-18, D. Stations 19-25, and E. Stations 27- 30. 48 160 Fig. 27. — H. M. Smith cruise 12. Topography in feet of the 75,0°F isotherm, contour interval 50 feet. 49 10 9 8 100 200 UJ h- UJ S 300 I t- U- iij o 400 600 ^^°~^==- U^ ^- - 24^^g ■j;::::;^-- J . — ■ — 2__— — - ""^ 25-c::::;33 26— — " — " — . --,.,^^_ • 27>~^ N 100 200 £. 300 - X I- CL UJ Q 400 500 - 600 X H Q 100 200 300 400 500 - 600 Fig. 28. -- H. M. Smith cruise 12. Profiles of sigma-t, isopleth in- terval 0.2. A. Stations 1-5, B. Stations 6-10, C. Stations 11-18, D. Stations 19- 25, and E. Stations 27-30. 50 180 180 ISO 180- 160 '.180 -180'' ,180 .180 23' 22° - 21' 20' 19' 18' -I r . ^300 -260 Fig. 29.-- H. M. Smith cruise 12. Topography in meters of the 23.2, 24.0, 25.0, and 26. 0 sigma-t surfaces. Contour interval 20 meters. A. 23.2, B. 24.0, C. 25.0, and D. 26.0 surfaces. 51 10 UJ 400 a • • • * — 350 >350 ^350 . . ^— — ' — ^ — ^ :::^^^ —34 4 \. --_34 2 - < 34 2 • - ~ 342^' ^ N • ^^ • - (B) 24 23 22 21 20 19 1/5 iij 200 300 - tu 400 500 600 100 — 200 - (/) a: 2 I I- Q. LlI Q 300 400 - 500 - 600 Fig. 30. --H. M. Smith cruise 12. Profiles of salinity in °/oo, iao- haline interval 0.2 °/oo. A. Sta- tions 1-5, B. Stations 6-10, C. Stations 11-18, D. Stations 19- 25, and E. Stations 27-30. 52 23° 160° 159° 158° 157° 156° 155° 18° 154° Fig. 31, --H. M_. Smith cruise 12. Surface salinity in °/oo, isoha- line interval 0. 10 °/oo. 53 — 200 - a: Q- UJ a 300 400 - 500 600 I I- CL UJ Q — 200 -r 300 400 500 600 Fig, 32. --Ji. M. Smith cruise 12. Profiles of inorganic phosphate in (ig at/1, isopleth interval 0.2 jig at /I. A. Stations 1-5, B, Stations 6-10, C. Stations 11-18, D. Sta- tions 19-25, and E. Stations 27-30, 54 3000 I60°W 158° 157° LONGITUDE 5000 Fig. 33. --Cross section of the Windward or High Islands of the Hawaiian Archipelago. 55 Remarks about the oceanographlc data Weather was recorded according to the ww code as it appears in The U.S. Weather Bureau Circular M, Instructions to Marine Meteorological Observers. Wind velocity was measured using an anemometer located 30 m. above the sea surface. In the tabulated data, the horizontal line(3) between depths separates the two or more casts necessary during the particular station. Whenever there is no doubt concerning data being in error (Nansen bottle pretrip, bottle leakage, etc.), these data are not carried in the tabulations and a footnote is appended. If values are doubtful, but there is no positive evidence of an error, the data are carried with appropriate footnotes. When the interpolated and calculated values are shown for greater depths than the observed values, they were obtained by extrapolation using the data from adjoining stations as a guide. 56 STATION 1 M/V Hugh M. Smith: Cruise 1, 18"50'N., 155 49'W., Decem- ber 17, 1949. Messenger time: 2313 OCT. Weather: scattered clouds, cirrus. Wind: 100°, 4 kt. Sea: 3-5 ft. Wire angle: 42°. Depth of water: 1400 f. OBSERVED DEPTH T S o-t oz PO4-P (m) (°C) (O/oo) (ml/1) (NLg at/1) 00 34.42 4.84 18 24.42 34.42 23.10 4.80 36 24.52 34.70 23.26 4.82 70 24.41 34.79 23.38 4.84 133 19.70 34.89 24.77 4.84 193 16.20 34.55 25.37 4.01 253 12.09 34.18 25.96 3.88 374 08.73 34.14 26.51 2.40 497 06.75 34.11 26.77 1.57 623 05.94 34.20 26.95 0.86 INTERPOLATED AND CALCULATED DEPTH T S o-t AD ADIOOO- AD (m) (°C) ("/oo) (dyn. m) (dyn. m) 00 24.51 34.42 23.05 0.000 1.899 10 24.43 34.42 23.08 0.048 1.851 20 24.45 34.42 23.09 0.096 1.803 30 24.50 34.58 23.20 0.144 1.755 50 24.46 34.74 23.33 0.236 1.663 75 24.42 34.80 23.38 0.350 1.549 100 24.12 34.86 23.52 0.462 1.436 150 18.95 34.82 24.91 0.651 1.248 200 16.05 34.53 25.40 0.796 1.104 250 12.42 34.20 25.91 0.916 0.982 300 10.49 34.16 26.23 1.013 0.881 400 08.24 34.13 26.57 1.18 3 0.710 500 06.70 34.11 26.78 1.334 0.565 600 06.03 34.13 26.92 1.463 0.436 700 05.69 34.24 27.01 1.581 0.318 800 05.41 34.30 27.09 1.693 0.206 1000 05.03 34.40 27.22 l.»99 0.000 57 STATION 2 M/V Hugh M. Smith: Cruise 1, 18°32'N. , 156°15'W., Decem- ber 18, 1949. Messenger time: 0438 GCT, Weather: scattered clouds, cirrus. Wind: 130°, 4 kt. Sea: 3-5 ft. Wire angle: 45°. Depth of water: 2500 f. OBSERVED DEPTH T S W ber 19, 1949. Messenger time: 2016 GCT. clouds, form not recorded. Wind: 310 , 1 kt Wire angle: 15°. Depth of water: 1500 f. Decem- Weather: scattered Sea: N. , 157 06'W, , Decem- ber 21, 1949, Messenger time: 0555 GCT. Weather: scattered clouds, cumulus. Wind: 320 , 2 kt. Sea: < 1 ft. Wire angle: no observation. Depth of water: 2500 f. OBSERVED DEPTH T S N. , 159°14'W.. July 22, 1951. Messenger time: 0211 GCT. Weather: not recorded. Wind: 020° 14 kt. Sea: not recorded. Wire angle: 00 . Depth of water: 2500 f. OBSERVED DEPTH T S «rt 02 PO4-P (m) (*»C) r/oo) (ml/1) (W at/1) 04 2b. bO 34,77 22.69 4.75 20 26.48 34.78 22.74 4.75 40 26.49 34.77 22.73 4.75 80 23.60 35.01 23.79 5.16 155 19,76 35.06 24.89 4.56 300 10.74 34.18 26.20 4.26 438 07,02 34.01 26.66 2.64 585 05.64 34,23 27.01 1.09 725 05.00 34,34 27.18 0.95 874 04.4 0 34.42 27.30 1.06 1163 03.61 1/ 1454 02.96 34."5l 27.52 1.69 1753 02.42 34.57 27.61 1.96 INTERPOLATED AND CALCULATED DEPTH T S C) (*»/oo) (ml/l) (W at/1) 00 26.20 34.63 22.70 4.83 10 26.26 34.60 22.67 4.79 20 26.24 34.60 22.63 4.79 42 25.90 34.75 22.90 4.92 81 24.22 34.92 23.54 5.18 151 20.02 35.00 24.78 4.86 210 14.66 34.42 25.62 4.17 269 10.36 34.17 26.26 3.42 330 08.78 34.19 26.54 2.43 387 07.88 34.23 26.71 2.02 503 06.42 34,37 27.02 2.29 617 05.72 34.35 27.10 0.86 775 05.08 34.44 27.25 1/ INTERPOLATED AND CALCULATED DEPTH T S »-t AD ADIOOO- AD (m) (°C) (°/oo) (dyn. m) (dyn. m) 00 26.24 34.63 22.70 0.000 1.777 10 26.26 34.60 22.67 0.052 1.725 20 26.24 34.60 22.67 0.104 1.673 30 26.16 34.63 22.72 0.155 1.622 50 25. SO 34.77 22.94 0.256 1.521 75 24.47 34.90 23.44 0.374 1.403 100 23.16 34.98 23.89 0.481 1.296 150 20.40 35.01 24. 6S 0.665 1.112 200 15.71 34.55 25.4? 0.S13 0.964 250 11.30 34.19 26.11 0.926 0.851 300 09.42 34.17 26.42 1.017 0.760 400 07.71 34.24 26.74 1.170 0.607 500 06.48 34.36 27.00 1.295 0.482 600 05.81 34.34 27.07 1.405 0.372 700 05.34 34.39 27.17 1.508 0.269 800 05.00 34.45 27.26 1.603 0.174 1000 04.50 34.49 27.34 1.777 0.000 IJ Sample spoiled. 84 STATION 10 M/V Hugh M. Smith; Cruise 10, 20°17'N., 158"*21'W., July 24, 1951. Messenger time: 1733 GCT. Weather: not recorded. Wind: 060°, 12 kt. Sea: not recorded. Wire angle: 42°. Depth of water: 2520 f. OBSERVED DEPTH (m) T {°C) S (O/oo) "■t Oz (ml/l) PO4-P (M at/l) 00 26.30 34.88 22.88 5.03 07 26.26 34.92 22.91 4.81 21 26.28 34.92 22.90 4.85 41 24.10 34.97 23.61 5.16 79 20.50 35.01 24.65 4.97 156 14.84 34.48 25.63 4.15 233 10.64 34.16 26.21 4.12 307 08.65 34.14 26.52 2.62 383 07.28 34.17 26.75 2.09 '*5't 06.55 34.22 26. «9 1.18 608 05.56 34.39 27.15 1.19 lib 04.94 34.41 27.24 1.01 962 04.21 34.44 27.34 1.22 INTERPOLATED AND CALCULATED DEPTH T S "t AD ADIOOO- AD (m) (*'C) (°/oo) (dyn. m) (dyn. m) 00 26.26 34.88 22.88 0.000 1.586 10 26.26 34.92 22.91 0.050 1.536 20 26.28 34.92 22.90 0.099 1.487 30 26.28 34.93 22.91 0.149 1.437 50 22.56 35.01 24.08 0.237 1.349 75 20.79 35.02 24.58 0.328 1.258 100 19.01 34.93 24.98 0.408 1.178 150 15.30 34.54 25.57 0.545 1.041 200 12.07 34.23 25.99 0.658 0.928 250 10.03 34.16 26.31 0.754 0.832 300 08.80 34.15 26.50 0.838 0.748 400 07.08 34.19 26.79 0.984 0.602 500 06.26 34.26 26.95 1.110 0.476 600 05.63 34.39 27.13 1.219 0.367 700 05.20 34.40 27.19 1.317 0.269 800 04.84 34.41 27.24 1.411 0.175 1000 04.14 34.44 27.34 1.586 0.000 85 STATION 1 1 M/V Hugh M. Smith: Cruise 10, 18°45'N. , 157°30'W., July 25, 1951. Messenger time: 0646 GCT. Weather: 01, cloud cover- age not recorded. Wind: 070 , 16 kt. Sea: 1-3 ft. Wire angle: 32°. Depth of water: 2425 f. OBSERVED DEPTH (m) T («C) S (°/oo) ^"--^ - Average value used in constructing temperature-.alxnity curve. 2/ Value did not fit the temperature-salinity curve. 93 STATION 19 M/V Hugh M. Smith: Cruise 10, 21°51'N., 156°45'W. , July 27, 1951. Messenger time: 0308 GCT. Weather: 01, cloud cover- age 8. Wind: 090°, 18 kt. Sea: 3-5 ft. Wire angle: 25°. Depth of water: 2750 f. OBSERVED DEPTH T S o-t oz PO4-P (m) (°C) (O/oo) (ml /I) (W at/1) 01 25.60 34.66 23.00 4.90 09 25.59 34.63 22.74 4.85 27 25.54 34.60 22.70 4,87 53 24.86 34.62 22.76 5,08 106 22. 6S 35.09 23.32 5.14 206 17.72 34.39 24.63 4.80 304 11.76 34.10 25.96 3.60 396 08.82 34.05 27.08 3.55 496 06.68 34.04 27.56 2.23 590 05.63 34.14 27,32 1.25 736 04,35 34.34 27.45 1.34 983 03.77 34.42 27.54 1.39 1182 03.34 1/ INTERPOLATED AND CALCULATED DEPTH T S o-t AD AD 1000- AD (m) (°C) ("/oo) (dyn. m) (dyn. m) 00 25.57 34.66 22.93 0.000 1.891 10 25.59 34.63 22.90 0.050 1.841 20 25.57 34.61 22.39 0.099 1.792 30 25.54 34.60 22,89 0.149 1.742 50 25.54 34.62 22,91 0,249 1.642 75 24.10 34.78 23,46 0.367 1.524 100 23.00 35.07 24,00 0,472 1.419 150 19.60 35.12 24,97 0,647 1.244 200 17.96 34.87 25,20 0,794 1.097 250 15.40 34.46 25,48 0,929 0.962 300 11.90 34.11 25,93 1,047 0.844 400 08.72 34.05 26,43 1,238 0.653 500 06.60 34,04 26,73 1,391 0.5 00 600 05.55 34.15 26,95 1.519 0.372 700 04.80 34.28 27,14 1.628 0.263 800 04.29 34.35 27,26 1.723 0.168 1000 03.72 34.43 27,35 1.891 0.000 }_l Value did not fit the temperature-salinity curve. 94 STATION 20 o M/V Hugh M. Smith; Cruise 10, 21 lO'N.. 156 35'W., July 27, 1951. Messenger time: 0938 GCT. Weather: 01, cloud cover- age not recorded. Wind: 060 , 3 kt. Sea: 1-3 ft. Wire angle: not recorded. Depth of water 256 f. OBSERVED DEPTH (m) T CO S C/oo) o-t oz (ml/l) PO4-P {^g at/1) 00 10 24 49 99 197 295 344 25.20 25.20 25.20 25.06 23.28 19.54 11.10 09.77 34.78 34.76 34.77 34.78 35.03 35.09 34.11 34.14 23.14 23.12 23.13 23.18 23.90 24.97 26.08 26.34 4.87 4.88 4.88 4.88 5.12 4.63 4.30 3.38 INTERPOLATED AND CALCULATED DEPTH T S o-t AD AD 1000-AD (m) (**C) ("/oo) (dyn. m) (dyn. m) 00 25.19 34.78 10 25.20 34.76 20 25.20 34.76 30 25.19 34.77 50 25.05 34.78 75 24.22 34.66 100 23.27 35.03 150 21.38 35.20 200 19.40 35.07 250 14.55 34.37 300 11.02 34.11 95 STATION 21 M/V Hugh M. Smith: Cruise 10, 20"50'N., 156 45'W.. July 27. 1951. Messenger time: 1340 GCT. Weather: 01, cloud cover- age not recorded. Wind: 060 6 kt. Sea: < 1 ft. Wire angle: 00" Depth of water: 27 f. DEPTH (m) (°C) OBSERVED S r/oo) N. , 156°39'W., July 27, 1951. Messenger time: 1837 GCT. Weather: 01, cloud cover- age 2. Wind: 060°, 24 kt. Sea: 3-5 ft. Wire angle: 38°. Depth of water: 1200 f. OBSERVED DEPTH T S C) (°/oo) (ml/1) (M *t/l) 00 25.50 34.68 22.96 4.90 10 25.53 34.65 22.94 4.92 30 25.46 34.64 22.95 4.90 59 24.92 34.64 23.12 5.07 116 21.66 34.96 24.30 5.01 233 12.44 34.24 25.94 4.26 346 09.04 34.23 26.53 2.39 455 06.36 34.08 26.80 1.89 568 05.42 34.22 27.03 0.70 678 05.00 34.38 27.21 0.85 903 04.38 34.49 27.36 1.04 1122 03.74 34.52 27.45 1.33 1337 03.27 34.52 27.50 1.44 INTERPOLATED AND CALCULATED DEPTH T S C) (••/oo) (ml /I) (m* *t/l) 00 26.70 34.88 22.75 0.28 09 26.61 34.88 22.77 0.30 27 26.57 34.87 22.78 0.33 52 26.40 34.87 22.83 0.26 100 23.60 34.92 23.72 0.39 192 13.80 34.91 25.02 0.64 281 11.52 34.20 26.08 1.52 , 281 1.571/ 368 08.792/ 34.14 26.50 2.25 368 08.852/ 34.14 26.49 458 07.36 34.20 26.76 2.83 545 06.02 34.23 26.96 3.15 722 04.96 34.42 27.24 3.39 904 04.38 34.47 27.35 3.27 1097 03.84 34.47 27.40 3.40 1097 3.34i/ INTERPOLATED AND CALCULATED DEPTH T S 't AD ADIOOO-AD (m) (°C) (°/oo) (dyn. m) (dyn. m) 00 26.68 34.88 22.75 0.000 1.875 10 26.61 34.88 22.77 0.051 1.824 20 26.59 34.88 22.77 0.102 1.773 30 26.56 34.37 22.78 0.153 1.722 50 26.41 34.87 22.02 0.254 1.621 75 26.00 34.86 22.94 0.380 1.495 100 23.60 34.92 23.71 0.494 1.381 150 21.15 35.03 24.49 0.687 1.188 200 18.19 34.85 25.12 0.848 1.027 250 14.73 34.47 25.64 0.931 0.894 300 10.65 34.17 26.21 1.039 0.786 400 08.24 34.14 26.58 1.260 0.615 500 06.69 34.22 26.36 1.399 0.476 600 05.56 34.29 27.06 1.516 0.359 700 05.06 34.40 27.21 1.617 0.258 800 04.69 34.45 27.29 1.708 0.167 1000 04.09 34.47 27.37 1.875 0.000 U Values do not agree within 0.02 p.g at/1 tolerance. Average value used in constructing phosphate- temperature curve. ".' Thermometers did not agree within 0.02 C toleramce. Average value used in constructing temperature-depth curve. 117 M/V HuQ Smith: Cruise Messenger time: 0254 GCT STATION 10 12, 20°18'N., Weather: 02, 158°22' W. October 27, 1951. cloud coverage 7. Wind: 180 11 kt. Sea: 1-3 ft. Wire angle: 31 . Depth of water: 2520 f. OBSERVED DEPTH T S o-t O2 PO4-P (m) (°C) (°/oo) (ml/1) (jig at/1) CC 26.ro 3 4 . C 6 22.69 0.34 09 26.75 34.86 22.71 0.31 09 0.381/ 25 26.70 34.86 22.73 0.40 0.33i' 25 49 26.3 8 34.82 22.80 0.36 9e 23.45 34.87 23.73 0.33 92 0.4li/ 192 18.65 34.91 25.06 0.65 281 12.01 34.25 26.02 1.44 2S1 1.49i/ 35C 0S.9l2/ 34.13 26.47 2.10 36? o:.98Z/ 34.13 26.46 458 07.45 34.18 26.73 2.77 546 05.24 34.25 26.95 3.16 729 05.01 34.42 27.24 3.29 915 04.34 34.46 27.34 3.19 1105 03.74 34.43 27.3" 3.24 INTERPOLATED AND CALCULATED DEPTH T S o-t AD AD 1000- AD (m) (°C) (°/oo) (dyn. m) (dyn. m) CO 26.83 34.86 22.68 0.000 1.873 10 26.74 34.86 22.71 0.052 1.821 20 26.71 34.86 22.72 0.103 1.770 30 26.68 34.86 22.73 0.154 1.719 50 26.35 34.82 22.80 0.257 1.616 75 24.99 34.83 23.23 0.379 1.494 100 23.38 34.58 23.75 0.489 1.384 150 21.08 35.03 24.51 0.681 1.192 200 18.00 34.84 25.16 0.840 1.033 250 14.10 34.42 25.73 0.970 0.903 300 11.00 34.19 26.16 1.077 0.796 400 08.39 34.14 26.56 1.251 0.622 500 06.82 34.21 26.84 1.393 0.4"0 600 05.83 34.32 27.05 1.512 0.361 700 05.19 34.40 27.19 1.614 0.259 800 04.67 34.46 27.30 1.705 0.168 1000 04.12 34.46 27.36 1.873 0.000 —' Values do not agree within 0.02 fig at/1 tolerance. Average value used in constructing phosphate- temperature curve. £/ Thermometers did not agree within 0.02°C tolerance. Average value used in constructing temperature-depth curve. 118 STATION 1 1 M/V Hugh M. Smith; Cruise 12. 18°47'N. . 157°27'W.. Octo- ber 27, 1951. Messenger time: 1724 OCT. Weather: 00, cloud coverage 6. Wind: 160°, 19 kt. Sea: 5-8 ft. Wire angle: 00°. Depth of water: 2450 f. OBSERVED DEPTH T S o-t oz PO4-P (m) CC) (*>/oo) (ml /I) (W at/1) 00 26.50 34.79 22.74 0.18 10 26.49 34.78 22.74 0.27 30 26.26 34.83 22.84 0.21 59 26.06 34.79 22.88 0.34 119 22.74 35.00 24.03 0.30 237 14.22 34.36 25.66 1.04 353 08.89 34.19 26.52 2.22 466 07.75 34.30 26.78 2.71 583 06.68 34.35 26.97 2.98 695 05.78 34.37 27.10 3.14 924 04.61 34.42 27.28 3.12 1142 03.92 34.50 27.42 3.04 1352 03.28 34.52 27.50 3.02 INTERPOLATED AND CALCULATED DEPTH T S /oo) /oo) (ml/1) (^g at/1) 00 26.50 34.75 22.71 0.33 09 26.48 34.75 22.72 0.34 27 26.50 34.83 22.77 0.35 55 25. S6 34.82 22.96 0.32 108 22.95 35.06 24.02 0.34 211 IS. 76 34.89 25.02 0.50 313 10.41 34.15 26.24 1.82 406 08.54 34.21 26.60 2.45 506 07.06 34.24 26.83 2.94 601 06. OS 34.32 27.03 3.13 800 05.05 34.40 27.22 3.13 1002 04.16 34.45 27.36 3.06 1207 03.62 34.43 27.39 3.06 INTERPOLATED AND CALCULATED DEPTH T S