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FISHERY BULLETIN: VOL. 72, NO. 4 

 80° 70° 



Figure 1. — Geopotential anomaly, in joules per kilogram (dynamic decimeters), at the sea surface relative to 500 db in February- 

 March 1967. EASTROPAC cruises Ar^go 11, David Starr Jordan 12, Rockaway 13, and Alaminos 14. The position of the intertropical 

 convergence zone at the eastern and western ends of the map is indicated by triangles. 



summer.) However, the coverage of the 

 southern-winter map (Figure 4) is limited to lat. 

 10°S, and this suggestion cannot be confirmed by 

 winter data. None of the drift charts examined 

 shows an eastward current near this latitude in 

 the eastern South Pacific, but their data are too 

 sparse to draw a definite conclusion. Because of its 

 low speed, the countercurrent, indicated by the 

 distribution of geopotential anomaly (Figures 1 

 and 7), may well be buried in the westward Ekman 

 drift due to the prevailing southeasterly trades 

 and may be observed only when the trade winds 

 are unusually weak. 



Peru Current 



In the region south of the equator and between 

 long. 90°W and the coast of South America, the 

 distribution of geopotential anomaly is irregular, 

 and its spatial variation is not large (Figures 1, 4, 

 and 7). This distribution suggests a dominance of 

 weak and broad flow with small-scale ir- 

 regularities such as eddies and countercurrents 

 (Wooster and Reid, 1963; Wyrtki, 1963). Partly 

 because of this fact and partly because of a rather 

 inadequate orientation of ship tracks in this area, 

 contouring is difficult; there are many other ways 



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