WATER MASSES AND CURRENTS OF THE OCEANS 207 



topography of the isobaric surfaces, this means that in Drake Passage 

 and the Scotia Sea the water does not flow parallel to the dynamic contour 

 lines but flows uphill. Within the Antarctic Ocean, this region is the 

 only one in which there is evidence of a marked discrepancy between the 

 lines of equal transport and the actual flow of water, and on the whole it 

 may be assumed that the transport lines give a fairly correct picture of 

 the character of the Circumpolar Current. 



A flow to the west near the Antarctic Continent is evident only 

 in the Weddell Sea area, where an extensive cyclonic motion occurs 

 to the south of the Circumpolar Current. The water masses that take 

 part in this cyclonic movement, however, are small compared to those of 

 the Circumpolar Current, and their velocities are small. 



Within the subantarctic region the current is also directed in general 

 from west to east, but only the southern portion of the waters close to the 

 Antarctic Convergence circulates around the Antarctic Continent and 

 forms part of the Circumpolar Current. In the Pacific Ocean the 

 northei'n portion belongs to the current system of that ocean. Thus, a 

 strict northern limit of the Antarctic Ocean cannot be established on 

 oceanographic principles, but a boundary region has to be considered 

 that, depending upon the point of view, may be assigned either to the 

 Antarctic Ocean or to the adjacent oceans. 



The total transport of the Antarctic Circumpolar Current must be 

 greater than is apparent from fig. 57, which shows only the transport 

 relative to the 3000-decibar surface. According to the figure the trans- 

 port through Drake Passage is about 90 million mVsec, whereas Clowes' 

 computations gave 110 millions above the 3500-decibar surface. It is 

 therefore probable that the absolute transport between the lines in fig. 57 

 is not 20 million, but at least 25 million m^. 



This discussion of the Circumpolar Current is based entirely on the 

 distribution of mass as derived from deep-sea oceanographic observations. 

 The surface currents have been determined independently by means of 

 ships' records and show that the flow of the surface water is governed 

 partly by the distribution of mass and partly by the effect of the prevail- 

 ing winds. Near the Antarctic Continent, easterly and southeasterly 

 winds blow away from the large land masses, but between latitudes 60° 

 and 40°S strong westerly winds prevail. Correspondingly one finds, as 

 seen on chart 4, westward surface currents prevailing near the border of 

 the Antarctic Continent and eastward surface currents at some distance 

 from the coast. In the Southern Hemisphere the wind drift deviates to 

 the left of the direction of the wind, and consequently the eastward sur- 

 face current shows a component toward the north. A divergence must be 

 present between the westward and the eastward surface currents, draw- 

 ing deep water toward the surface, and in the sections (fig. 58) this 

 divergence shows up close to the continent by the high temperature and 



