SECT. 3] 



EASTERN BOUNDARY CURRENTS 



275 



slow, and transport significantly less water than the western boundary currents. 

 In several important respects, however, they differ from the equatorward 

 currents. 



Since they flow toward higher latitudes, their surface waters are relatively 

 warm. The isopycnals and other isopleths tend downward toward the coast 

 (Figs. 16 and 17). so that, in accordance with the geostrophic approximation, 



1000 



DISTANCE OFFSHORE (km) 



Fig. 16. Profiles across Alaska Current at 53.5°N, July-August, 1957. (a)-(d) as in Fig. 

 (After Pacific Oceanographic Group, 1957.) 



the sea surface stands highest next to the coast. As shown by negative values of 

 the offshore Ekman transport (see page 268) in these regions, the surface drift 

 is convergent with the coast, so that light surface waters pile up at the bound- 

 ary. Coastal upwelling is not possible in such circumstances, and coastal 

 surface waters do not show the influence of this upward vertical motion. The 

 distributions of properties (Figs. 16 and 17) suggest that poleward flow extends 

 to depths greater than 1000 m in accordance with the conclusion of Bennett 

 (1959) that, in the Gulf of Alaska, northward flow extends to at least 2000 m. 



