readings were taken at 750 m[i, 665 mji, 645 m^, 

 630 mji, and 550 nnp.. Either before or cifter the 

 sample readings, the transmittance in a reagent 

 blank (90-percent acetone) was read at the same 

 wave lengths. Following the method of Richards 

 and Thompson (1952), the concentrations of 

 chlorophyll a, b, and c were calculated from the 

 results in terms thought to be equivalent to 

 milligrams per cubic meter. 



Oceanographic Observations 



The temperature-depth profiles drawn 

 from BT observations along sections of the 

 cruise track, as numbered in figure 7, are 

 shown in figure 8. Because of the close spacing 

 of the observations, particularly during the 

 eastward passage, and the chosen distance scale 

 for the plots, it was frequently desirable to omit 

 data from every second lowering. 



Figure 7. --Positions of temperature- 

 depth sections shown in figure 8. 



The salinity of water samples returned 

 to the laboratory was determined by a modifica- 

 tion of the Mohr method. This modification, 

 resulting in a stoichiometric end point, involves 

 the use of an adsorption indicator , phenosafranin, 

 in the presence of starch as a protective colloid 

 (Van L,andingham 1957). 



Inorganic phosphate determinations were 

 made both aboard ship and ashore (frozen 

 samples), using a modification of the molybdenum 

 method with the Automatic Servo-Operated 

 Photometer (Snodgrass et al. 1954. A sup- 

 plementary reducing agent, hydrazine sulphate, 

 was used to stabilize the color complex. With 

 this technique, although maximum color develop- 

 ment takes longer, the color complex is stable 

 for at least 7 days. 



The procedures for the treatment of the 

 observed data leading to the final tabulations 

 and the preparation of the station curves and the 

 vertical sections essentially followed those 



described by Stroup (1954). The principal vari- 

 ations involve the use of the t h e r nn osteric 

 anomaly in lieu of sigma-t and a technique of 

 graphical integration to deternnine the dynamic 

 heights (Montgomery and Wooster 1954; Klein 1.'). 



In this report the presentation of the 

 oceanographic data differs somewhat from that 

 in previous POFI publications. Only the ob- 

 served station data are tabulated (table 7). In 

 lieu of the tabulations of interpolated data at 

 standard depths, the station curves are repro- 

 duced (fig. 9). The anomaly at the surface 

 relative to the 700-decibar level is entered on 

 each graph. The 700 -meter reference level was 

 used because several of the casts did not pene- 

 trate to 1,000 meters. From these curves the 

 reader can see the station-to-station interpola- 

 tion introducedby the analyst during the drawing 

 of the curves, and in this form we believe the 

 data are nnore suitable for diversified types of 

 analyses. 



The vertical sections for the thermosteric 

 anomaly, geopotential anomaly (0/700db, neg- 

 lecting pressure terms in the specific volume 

 anomaly), salinity, dissolved oxygen, and 

 inorganic phosphate, figures 10 to 23, were 

 constructed following the method proposed by 

 Montgonnery (1954) and extended by Stroup (1954). 

 In order that the details in the region of the 

 thernnocline could be shown with greater clarity, 

 the sections are drawn only to the 500-meter 

 level. Because of the failure of the ASOP and 

 an insufficient supply of containers for the 

 frozen inorganic phosphate samples, the section 

 along 120°W. longitude extends only from the 

 surface into the thermocline and there is no 

 comparable section for the 140°W. longitude 

 leg. 



PUBLICATION PLANS 



Our plans for analyzing and publishing 

 the results of POFI's participation in 

 EASTROPIC are as follows. A report, listing 

 40 species of sea birds and describing varia- 

 tions in their distribution and abundance in 

 relation to the current system, has been pub- 

 lished in The Condor (King and Pyle 1957). There 

 will be a brief report on the 4°F. front near 

 4''N. latitude, 120°W. longitude, with a descrip- 

 tion of the associated biological and physical 

 phenomena. This will be followed by a compre- 

 hensive paper treating all aspects of the cruise 

 and utilizing as applicable the published results 

 of the EASTROPIC cruises of other agencies. 



— "A new method for processing oceano- 

 graphic data, " unpublished manuscript by Hans 

 Klein, Scripps Institution of Oceanography. 



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