98 U-S. NATIONAL MUSEUM BULLETIN 291 



mass that retains its identity entirely around the continent. Close 

 to the continent the temperature and salinity are slightly lower, and 

 they increase with distance from the continent. The Antarctic Cir- 

 cumpolar Water has the same characteristics as the Lower Deep Wa- 

 ter that lies at about 2000 m in the subantarctic region. 



Antarctic Bottom Water is characterized by extremely low tem- 

 perature and relatively high salinity. This water mass is fonned by 

 the admixture of cold (-1.9° C), fairly low salinity (34.62%o) Ant- 

 arctic shelf water and warmer (0.5° C), more saline (34.68%o) Ant- 

 arctic Circumpolar Water that lies close to the continent. The resulting 

 Bottom Water has a temperature around 0° and a salinity around 

 34.66%o; it has a high density of sigma-t= 27.86. Antarctic Bottom 

 Water is formed primarily in the Weddell Sea and it spreads north- 

 ward and eastward into the Atlantic, Indian, and Pacific Oceans. 

 In the Atlantic it is detected as far as 40°N (Wiist, 1935), and in the 

 Indian Ocean it has been identified in the Bay of Bengal and the 

 Arabian Sea between 10°-20°N (Kort, 1962). 



Water Movements 



The circulation of water masses of the Antarctic Ocean is governed 

 by wind forces at the surface and by parameter gradients at all depths. 

 Two types of movement occur : latitudinal, mainly from west to east 

 in the whole circumpolar water mass, and meridional, equally from 

 north to south and from south to north (or northeast, southeast) in 

 stratified masses. 



A narrow band of easterly winds close to the continent induces sur- 

 face waters to move westward around most of the continent. This East 

 Wind Drift of the Antarctic Surface Water involves a relatively small 

 volume of water that moves at a slow velocity. The movement of the 

 mam mass of Antarctic waters is from west to east, driven by the 

 strong and nearly continuous west winds that blow in the region be- 

 tween 40° and 60°S. The surface movement is referred to as the West 

 Wind Drift and the entire eastward circulation is termed the Ant- 

 arctic Circumpolar Current. Coincident with the boundary between 

 the easterly and westerly wind belts is an area of divergence at 

 the sea surface at about 65°S. In the Southern Hemisphere, wind 

 drift deviates to the left of the direction of the wind so that easterly 

 winds produce a southerly component and westerly winds a northerly 

 comi^onent to the surface currents. The resulting divergence creates 

 an upwelling of "warm," high-salinity deep water toward the surface. 

 The northern portion mixes with Antarctic Surface Water and moves 

 to the north and east. The southern component mixes with the cold 

 waters adjacent to the continent and moves south and west. In winter 



