262 



WOOSTER AND REID 



[CHAP. 11 



condition should be considered a relic of previous upwelling, rather than 

 evidence of active upwelling at the time of observation. 



b. Salinity 



In all but one of the eastern boundary currents, salinity appears to decrease 

 with depth to minimum values at depths of several hundred to a thousand 

 meters. Thus, the effect of coastal upwelling is to decrease surface salinity. 



1000 



DISTANCE OFFSHORE (km) 



Fig. 7. Profiles across Peru Current at 14°S, July, 1952. (a), (c), (d) as in Fig. 6. (MS 

 data from Scripps Institution of Oceanography.) 



Only in the case of the California Current (Fig. 6b) does salinity generally in- 

 crease with depth nearshore, where upwelling then causes an increase of surface 

 salinity. Offshore there is a complicated interdigitation of salinity minima and 

 maxima, reasons for which have been presented by Reid, Roden and Wyllie 



(1958). 



c. Density 



The vertical density structure closely parallels that of temperature, with iso- 

 pycnals ascending toward the coast. Where the vertical density gradient is 



