SECT. 3] 



EASTERN BOUNDARY CURRENTS 



263 



decreased near the coast by the descent of isopycnals below a hundred meters 

 or so, this structure is apparently associated with a poleward undercurrent 

 (see page 273). Comparison of the density structure in the Kuroshio and 

 California Currents (NORPAC Committee. 1960) shows the following 

 differences : 



1 . Greater width of the region with sloping isopycnals in the eastern bound- 

 ary currents. 



(c) (d) 



1000 



DISTANCE OFFSHORE (km) 



Fig. 8. Profiles across Peru Current at 33°S, May, 1958. (a)-(d) as in Fig. 6. (From data 

 of Ob Cruise 3, Institut Okeanologii ; MS data from I.G.Y. World Data Center A.) 



2. Greater slope of isopycnals in western boundary currents. 



3. Greater depth to which sloping isopycnals occur in the western boundary 

 currents. 



These differences in the density field are reflected in the character of the geo- 

 strophic flow in the two classes of currents. 



d. Oxygen 



In most parts of the ocean, dissolved oxygen decreases with depth from 

 values near saturation at the surface to relatively low values at an oxygen 



