CHAPTER V 

 General Distribution of Salinity, Temperature, and Density 



Salinity of the Surface Layer 



Surface Salinity. In all oceans the surface salinity varies with 

 latitude in a similar manner. It is at a minimum near the Equator, 

 reaches a maximum in about latitudes 20°N and 20°S, and again decreases 

 toward high latitudes. 



Table 10 contains average values of the surface salinity, the evapora- 

 tion, and the precipitation, as well as the difference between the last 



Fig. 15. Left: Average values of surface salinity for all oceans, and the difference, 

 evaporation minus precipitation, plotted against latitude. Right: Corresponding 

 values of surface salinity, and the difference, evaporation minus precipitation, plotted 

 against each other (according to Wiist). 



quantities, for the three major oceans and for all combined, according to 

 Wiist. On the basis of these values, Wiist has shown that for each ocean 

 the deviation of the surface salinity from a standard value is directly 

 proportional to the difference between evaporation, E, and precipitation, 

 P. In fig. 15 are plotted the surface salinities for all oceans and the 

 difference £' — P (in centimeters per year), as functions of latitude, and 

 the corresponding values of salinity and the difference, E — P, are 

 plotted against each other. Omitting the values at 5°N because they 

 disagree with all others, the values fall nearly on a straight line leading to 

 the empirical relationship 



S = 34.60 + 0.0175(^ - P). 

 71 



(V, 1) 



