Reading from north to south, we see that the first three curves may, when connpared 

 with those from several other cruises in figure 22, be considered as characteristic for the 

 Equatorial Countercurrent. The surface salinity is relatively low and, with increasing depth 

 down to a level of 50 to 100 meters, the temperature changes very markedly while there is re- 

 latively little change in salinity. The effect of this large temperature change on the vertical 

 distribution of density is well demonstrated in figures 8 to 11, where the values for sigma-t 

 increase from about 22. 5 g/1 to 25. 5 g/1 within a depth range of 10 to 25 meters. Below 300 

 nneters, the T-S relationship is characteristic of the Equatorial Pacific water (Sverdrup, et al. 

 1942, p. 707). Although cruise 15 did not include stations in the North Equatorial Current, 

 figure 23, giving the T-S relationship for various longitudes at 19 N. , illustrates the markedly 

 different characteristics of the adjacent waters to the north of the Countercurrent. 



The relatively low surface salinities in the more northerly station of cruise 15 (5°N. 

 to 9 N. ) reflect the high annual total precipitation in this region. Jacobs (1951, figure 41, p. 82) 

 shows that the annual total precipitation over the Pacific Ocean, 55 N. to 55 S. , averaged for 

 each 10 of latitude, reaches a maximum between the Equator and 10 N. 



For comparative purposes, a summary of the rainfall in the Line Islands, somewhat 

 to the west of the 140th meridian, is given in figure 24. The monthly mean rainfall is given for 

 four of the northern Line Islands (Palmyra, Washington, Fanning, and Christmas), for Maiden 

 Island in the soutljern Line Islands, and for Canton Island in the Phoenix group. The position of 

 each of these islands and the number of years of observations used for determining the means 

 are given in table 3 below. 



1/ The data for Palmyra Island were from unpublished 

 records provided by the U. S. Weather Bureau. 



2/ The data for Washington, Fanning, Christmas, and 

 Maiden Islands were taken from an unpublished re- 

 port prepared by C. E. Palmer (1953). 



3/ The data for Canton Island were from published 

 ~ records of the U, S. Weather Bureau (1954). 



Returning to Jacob's paper, his figures 43 and 44, page 85, show that on 140 W. , 

 between the Equator and 10°N. , precipitation exceeds evaporation during the spring (March- 

 May) and the summer (June-August). Hugh M. Smith cruise 15, May 28 to June 20, 1952, 

 bridges his classification for the two seasons. Our data for the years 1950-1953, and between 

 140 W. and I 80th nneridian, indicate that the latitudinal position for salinity minimum and the 

 maximum excess of precipitation over evaporation lies between 5 Jind 10 N. latitudes, rather 

 than centered on 5°N. latitude (see Jacob's figure 51 D, p. 95). However, the effect of the 

 horizontal flow (Equatorial Countercurrent and South Equatorial Current) on the surface sa- 

 linity is yet to be studied. These zonal currents may, and undoubtedly do, displace the areas of 

 maximum (or nninimum) salinity in the direction of the surface flow and away from areas of 

 maxinnum or minimim precipitation. 



