100 U.S. NATIONAL MUSEUM BULLETIN 291 



Divergence has already been discussed. The movements of water as- 

 sociated with the Antarctic Convergence are even more significant and 

 far reaching. The dynamics of the Antarctic Convergence are not fully 

 understood. Deacon (1937) considered that the Antarctic Convergence 

 is caused primarily by the deep water circulation. He reasoned that the 

 cold Antarctic Surface Water is prevented from sinking in the ant- 

 arctic region by the underlying warmer but higlily saline, more dense 

 Deep Water. But once the Antarctic Surface Water passes the region 

 where the Deep AVater climbs steeply toward the surface above the 

 Antarctic Bottom Water, the surface water is no longer held up and it 

 sinks below the warm, less dense Subantarctic Surface Water. Another 

 view is taken by Sverdrup (1934) ; he suggested that the convergence is 

 caused by the different types of circulation in the surface layers of the 

 antarctic and subantarctic regions. The themiohaline circulation of the 

 subantarctic region forces the warm, light surface waters to the south ; 

 the wind-driven circulation of the antarctic region drives the cold, 

 dense surface waters to tlie north. When these waters meet, the more 

 dense mass submerges. 



Wyrtki (1960) concluded that in regions of strong westerlies a zone 

 of convergence develops to the north of the axis of maximum wind 

 force and a zone of divergence develops to the south of the axis. As the 

 axis shifts north and south so do the convergence and divergence zones. 

 The degree of convergence and divergence vaiies with the strength 

 of the wind. Wexler (1959) similarly reasoned that the convergence 

 is caused by meteorological factors. Whatever the underlying cause 

 is, the result is the same. 



The water that sinks at the convergence all around the Southern 

 Ocean is characterized by a temperature of 2.2° C and a salinity of 

 33.80%o. As it sinks it very rapidly becomes mixed with water from 

 above, the Subantarctic Surface Water, and from below, the Deep 

 Water. The resulting water mass is the Antarctic Intermediate Water 

 that spreads northward throughout the southern portions of the three 

 oceans. In the Atlantic, where no equatorial water mass exists, the 

 Antarctic Intermediate Water spreads to 20° N whereas in the Pacific 

 and Indian Oceans it reaches only to about 10°S. The Antarctic Inter- 

 mediate Water is characterized as a salinity-minimum core that lies 

 between 800-1200 m between sigma-t surfaces of 27.20 and 27.40; 

 temperatures range between 3°-7° C. 



The circulation of the deep waters of the Southern Ocean is linked 

 with the occurrence of the Deep Water masses from the Atlantic, In- 

 dian, and Pacific Oceans. In the South Atlantic the Deep Water is 

 characterized as a core of high-salinity water flowing southward that 

 is sandwiched between the north-flowing Antarctic Intermediate 



