OCEANOGRAPHIC OBSERVATIONS ON THE 

 "E. W. SCRIPPS" CRUISES OF 1938 



INTRODUCTION 

 THE CRUISES OF 1938 



By 



H.U. SVERDRUP 



The new vessel of the Scripps Institution of 

 Oceanography, the "E. W. Scripps," was placed in 

 coEinission at the end of December, 1937, after 

 having been- remodeled and equipped for oceano- 

 graphic work. A description of the vessel is in- 

 cluded in this report, giving its dimensions and 

 its facilities for oceanographic vrork. 



In 1937 a cooperation had been established 

 with Dr. F. P. Shepard who, through a grant from 

 the Geological Society of America, v;as to have 

 the vessel at his disposal for investigation in 

 submarine geology every second month of 1938, be- 

 ginning in January. Thus the Scripps Institu- 

 tion would have the vessel available for its 

 particular purposes only during every ot.her month 

 of the year. The most advantageous plan there- 

 fore seemed to be to continue the type of survey 

 which had been conducted in 1937 in cooperation 

 with the California Division of Fish and Game 

 making use of the patrol vessel, the "Bluefin." 



Figure 1 shows the area off the coast of 

 soutliern California which was studied in 1937 

 and 1938. On the chart are indicated the loca- 

 tions of the stations which were to be occupied 

 in 1938, with the station numbers. Owing to 

 weather conditions not all the stations were oc- 

 cupied on certain cruises. Also, the exact lo- 

 cations vary slightly from those shown in this 

 chart, but in the maps showing the results of 

 the different cruises the actual positions are 

 indicated by dots. 



The work was planned to comprise observations 

 of temperature, salinity, and oxygen within the 

 layers where significant differences could be ex- 

 pected, determinations of phosphate phosphorus 

 if possible, and collection of phytoplankton at 

 seven different levels at and below the surface. 

 Except on Cruise I vertical net hauls for zoo- 

 plankton between 200 meters and the surface were 

 part of the routine program. 



The "Bluefin" cruises-"- had shown that great 

 contrasts in the hydrographic conditions exist 

 off the coast of southern California and had in- 

 dicated that marked changes in the character of 



H. U. Sverdrup and R. H. Fleming, "The Waters 

 off the Coast of Southern California, March to 

 July, 1937." Bull. Scripps Inst. OceanoK . 

 (19ifl), vol. U, no. 10, pp. 261-378. 



the currents took place during the early part of 

 the year. The "Bluefin" cruises had also shown 

 that significant differences in the character of 

 the waters occurred mainly above a depth of 500 

 meters, for which reason the hydrographic work 

 of the "E. W. Scripps" was limited to this depth. 

 Observations for temperature and water samples 

 were collected between the surface and a depth 

 great enough to insure that the deepest samples 

 were from a depth somewhat greater than 500 met- 

 ers, except on Cruise I when most stations were 

 worked to a depth of 1000 meters and one to a 

 depth of 3900 meters. Water samples vrere ob- 

 tained by Nansen reversing water bottles. Tem- 

 peratures were measured by means of standard re- 

 versing thermometers, using unprotected thermome- 

 ters on every third water bottle in order to de- 

 termine the depth at which the bottles reversed. 

 The salinity was determined by chloride titration, 

 three or more titrations being made on each sam- 

 ple if the difference between the first two ti- 

 trations exceeded 0.04 °/oo in salinity. The 

 oxygen content was determined on board by means 

 of the Winkler method. On the first three cruises 

 phosphate was determined by the method of Deniges, 

 using 1 ml. of acid-molybdate reagent to 100 ml. 

 of sea-water sample and direct visual comparison. 

 Results were calculated using the salt-error fac- 

 tor of 1.12 reported by Cooper^ for these condi- 

 tions. 



Table 1 shows the dates of the different 

 cruises, the number of stations occupied on each 

 cruise, the number of temperature, salinity, oxy- 

 gen, and phosphorus-content determinations, the 

 number of samples for study of phytoplankton, and 

 the number of vertical net hauls for zooplankton. 



On the cruises the stations were occupied in 

 ntimerical order with the following exceptions: 

 On Cruise III stations 31-15 were first occupied, 

 then station 13, and finally stations 1-12. On 

 Cruises IV and V station 13 was first occupied 

 and the other stations in numerical order, and on 

 Cruise VI the sequence was stations 13, 1-12, 23- 

 15, and 24-31. Cruises I, II, and V could not 

 be completed, owing to storms. Generally a some- 

 what rough sea was encountered to the north of 



' Jour. Mar. Biol. Assoc , 23 (1938): 171-78. 



[1] 



