SECT. 3] 



a. Temperature 



EASTERN BOUNDARY CURRENTS 



261 



Although temperatures throughout the water column are higher in the 

 North Atlantic than elsewhere in the ocean (Reid, 1961a), the thermal 

 structure is similar on most of the profiles in that near-surface temperatures are 

 lower nearshore with shallow isotherms ascending toward the coast. The 



(o) (b) 



(c) (d) 



1000 



DISTANCE OFFSHORE (km) 



Fig. 6. Profiles across California Current at 32.5°N, September, 1955 (phosphate from 

 August-September, 1950). (a) Temperature, °C ; (b) salinity, % ; (c) dissolved oxygen, 

 ml/1. ; (d) inorganic phosphorus, [i.g-atoms/1. (After NORPAC Committee, 1960, and 

 Scripps Institution, 1960.) 



general coastwards rise of the thermocline is indicative of the distribution of 

 mass associated with the equatorward geostrophic circulation. In some cases 

 (Figs. 6a, 7a, 9a) the vertical thermal gradient decreases close to the boundary, 

 with the upper isotherms rising and the deeper isotherms sinking toward 

 shore. Where higher temperatures are thus found at depth nearshore, the 

 presence of a poleward undercurrent is indicated (see page 273). Hart and 

 Currie (1960) suggest that, when isotherms are observed to ascend toward the 

 coast but a strong vertical thermal gradient is still present close inshore, this 



