450 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1963 



Figure 1. — Map of the Southern Ocean. (After G. A. Knox, 1960, Proc. Roy. Soc. 



Ser. B., vol. 152.) 



moving northward into the subtropical regions. There are two 

 regions in which the northward movement is strongly noted, one 

 being where the South Island of New Zealand lies athwart the north- 

 ern portion of the West Wind Drift, and the other, the tip of South 

 America. In both cases major currents are deflected northward by 

 these projections. 



To the south, adjacent to the Antarctic Continent, there is a west- 

 ward-flowing current, feeble in comparison to the West Wind Drift, 

 but nonetheless important in the distribution of the near-ice animals, 

 for it circulates slowly in a counterclockwise direction, opposite to 

 the stronger West Wind Drift. The East Wind Drift is not com- 

 pletely circumpolar, for in the region of the Scotia Arc it is broken 

 and there is not a completely circumpolar near-shore current. 



Temperature gradients between the Antarctic waters and the warmer 

 waters of the Tropics are not even, but are rather concentrated at two 

 zones which surround the Antarctic Continent. These zones of high 

 temperature gradient are known as convergences; the inner one is 

 the Antarctic Convergence and the outer is the Subtropical Conver- 



