Robert L. Charnell - HL - Field Party Chief 



Barbara E. Boldt - HL 



David Y. Hashimoto - HL 



John L. Matthews - HL 



Lloyd T. Watarai - HL 



Vincent Hoeman - Smithsonian Institution 



Warren King - Smithsonian Institution 



OBSERVATIONS-'' 



Current 



Eight drift bottles, supplemented by plastic- 

 enclosed drift cards (Barkley, Ito, and Brown, 

 1964) during the first and last days of each 

 cruise, were released at each BT cast. Two 

 current stations were occupied each cruise; 

 both Ekman and Roberts current meters were 

 used. 



In addition to the regular Nansen and BT 

 casts shown in figure 1, BT casts were made 

 at 18.5-km. (10-nautical-mile) intervals for 

 studies of variability between stations 2 and 4, 

 17 and 19, and 23 and 25. Surface temperatures 

 and salinity samples were taken from an inside 

 pump system which has an intake at a depth 

 of 8 feet. A Hytech Model 9006 Salinity - 

 Temperature-Depth Measuring Systems/was 

 used during the cruises to collect additional 

 data at stations south of 14° N. These data are 

 not presented in this report. 



To supplement the physical oceanographic 

 data presented in this report, additional infor- 

 mation of the following types was obtained. 



Biological 



A 1/2-hour surface plankton tow was taken 

 daily at 2000 hours with a 1-m. net. Flyingfish 

 which stranded themselves on deck were col- 

 lected daily. Regular observations of fish 

 schools, sea mammals, and birds were supple- 

 mented by more detailed bird counts by ob- 

 servers from the Smithsonian Institution. 



Meteorological 



Rain measurements as well as standard 

 weather observations were taken four times 

 daily. Radiation from sun and sky was meas- 

 ured and recorded daily with kn Eppley pyra- 

 nometer. These observations were supple- 

 mented by daily color photographs of clouds. 

 Surface long wave radiation measurements 

 were taken on the night BT stations with the 

 Suomi-Kuhn net radiometer. 



— All data not presented in this report are on 

 file at the Bureau of Commercial Fisheries Bio- 

 logical Laboratory, Honolulu, Hawaii 96812 



2/ 



— Trade names referred to in this publication 



do not imply endorsement of commercial products. 



PREPARATION OF DATA 



standard oceanographic procedures were 

 employed in the preparation of the data for this 

 report. Salinity determinations were made on 

 the University of Washington salinity bridge 

 (Paquette, 1958). Duplicate determinations 

 were made with an induction salinometer. When 

 values differed more than 0.02 °/oo, the salinity 

 was redetermined on the U.W. salinity bridge, 

 and the mean of the salinity bridge determina- 

 tions was reported. Oxygen concentrations 

 were determined by the modified Winkler 

 method (Thompson and Robinson, 1939). Inor- 

 ganic PO^-P was determined by the procedure 

 of Robinson and Thompson (1948) as modified 

 at the University of Washington. All thermom- 

 eters had been calibrated at HL since April 

 1962. The reported temperatures are esti- 

 mated to be accurate to +0.02° C. Application 

 of corrections to protected and unprotected 

 thermometer readings and computations of 

 thermometric depths and L-Z values were 

 performed with an IBM 7040 digital computer at 

 the University of Hawaii Computing Center with 

 a program written at HL. Depths were deter- 

 mined by the use of values from the L-Z curve 

 for the actual depth. This procedure gave depth 

 estimated to be within +10 m. down to 1,000 m. 

 and within +1 percent below 1,000 m. 



Sigma-t, specific volume anomaly, and the 

 dynamic height were computed on the IBM 7040 

 computer by the program prepared at HL and 

 based on equations given by LaFond (1951). 

 The computer also was used to interpolate all 

 properties at standard depths by means of a 

 subroutine furnished by the University of Wash- 

 ington Oceanography Department and based on 

 the interpolation method outlined by Rattray 

 (1962). 



In the region of study, a sharp thermocline 

 generally separates a surface mixed layer from 

 the subsurface waters. Only infrequently do 

 Nansen casts adequately define this configura- 

 tion, with the result that the interpolation pro- 



