The north-south cross section in the western Ross Sea, south to Ross island, 

 shows a thin layer of modified Circumpolar Water mixed with Antarctic Surface 

 Water above and Shelf Water below (Fig. 23). Circumpolar Water influence has 

 a weak core at about 50 to TOO meters depth centered on Station B-03. Below this 

 level, a mixed layer of modified Circumpolar Water and Shelf Water lies over 

 Shelf Water along this entire cross section . A thin layer of Antarctic Surface Water 

 about 30 meters thick appears at the northern-most station, B-01 (Fig, 24) . A 

 slight temperature -oxygen indication of Circumpolar Water influence is centered 

 at 75 meters. Below about 100 to 120 meters, oxygen and temperature show what 

 may be effects of mixing of modified Circumpolar Water residuum with Shelf Water. 

 Moreover, based on salinity-temperature criteria, pure Shelf Water is present from 

 about 90 meters to bottom . 



Along the Victoria Land Coast, a layer of Antarctic Surface Water 50 to 120 

 meters thick lies over Shelf Water (Fig. 25). Station E-11 at the western end of 

 this series shows the seasonal effect of surface cooling (Fig. 26), extending down- 

 ward about 30 meters into Antarctic Surface Water. This water persists to about 

 50 meters and mixes with Shelf Water below this depth . Farther north along the 

 coast, modified Circumpolar Water extends westward but does not reach the coast 

 (Fig. 9). It modifies both the Antarctic Surface Water and the underlying Shelf 

 Water. At Station E-12 nearest shore, salinity and sigma-t values indicate the 

 presence of Antarctic Surface Water, and Shelf Water extends from about the 200- 

 meter level to bottom. 



The Circumpolar Water influence is recognizable off Cape Adore (Figs. 27 and 

 28). Southeast of Cape Hallett, the Circumpolar Water core lies at about lOOmeters, 

 and is mixed with Antarctic Surface Water above and Shelf Water below. Toward the 

 coast, modified Circumpolar Water influence on the Antarctic Surface Water is 

 evident based on the temperature and salinity data . 



C. Summary and Conclusions 



From the data presented, it is evident that warmer water from oceanic depths 

 moves in over the continental shelf and extends as a wide tongue into much of the 

 Ross Sea. The lateral and vertical extent of this warm-water penetration into the 

 Ross Sea during the Austral summer now has been generally described. The intru- 

 sive mass brings with it temperatures warm enough to influence significantly ice 

 conditions in summer. The water types of the Ross Sea have been defined further 

 and their structure, distribution, and limits have been discussed. 



It is anticipated that additional data may permit a more comprehensive in- 

 terpretation and analysis of Antarctic oceanography. 



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