C. Winter Water 



Winter Water, along with Antarctic Surface Water, composes the upper 

 water mass of the Ross Sea. As the designation implies, this water type 

 forms during the winter season, when surface cooling and sea ice formation 

 create a column of relatively homogeneous water near the freezing point. 

 Meteorological data indicate that during the winter such isothermal con- 

 ditions could easily form (U.S. Navy Weather Research, 1961). Winter 

 Water is described as having temperatures characteristically near the 

 freezing point with corresponding uniform salinities (Mosby, 1934). Thus, 

 Winter Water may be defined as water with temperatures ranging from -1,70°C 

 (28.94°F) to -1.90°C (28.58°F), salinities of 34.15 to 34.45%o , and sigma-t 

 values of 27.50 to 27.75 (U.S. Naval Oceanographic Office, 1965). 



Winter Water is found throughout the Ross Sea. In the western portion, 

 Winter Water is found as an intermediate layer between Antarctic Surface 

 Water and Shelf Water (Figs. 6, 7, 8, 9), and between Antarctic Surface 

 Water and Modified Circumpolar Water (Fig. 10). Most of the Winter Water 

 in the western Ross Sea is modified by intrusion of the circumpolar water 

 mass. Only in the extreme west and near the Ross Ice Shelf is -Winter 

 Water present without the presence of Modified Circumpolar Water (Fig. 16). 



In the eastern Ross Sea, Winter Water is present under much the same 

 conditions. During the austral summer, 1962, Winter Water was found in 

 the extreme southeast with no Modified Circumpolar Water intrusion (U.S. 

 Naval Oceanographic Office, 1965). During the austral summer, 1964, all 

 stations in the eastern Ross Sea. were observed to have Winter Water in 

 varying amounts , as an intermediate layer between Antarctic Surface Water 

 and Modified Circumpolar Water. 



From examination of data collected on previous DEEP FREEZE operations, 

 it was observed that Winter Water appears to exist in conjunction with 

 Modified Circumpolar Water throughout the Ross Sea, except in the extreme 

 southwest and near the Ross Ice Shelf. 



D, Antarctic Circumpolar Water 



Antarctic Circumpolar Water is a southward continuation of Antarctic 

 Deep Water. This water is characterized as having temperatures warmer than 

 +0.50°C (32.90°F) and salinities somewhat greater than 34.70 %o (U.S. 

 Naval Oceanographic Office, 1965). 



Originally found at depths of about 2,000 meters (6,562 feet) near the 

 Antarctic Convergence, this water rises to near the surface as it approaches 

 the Ross Sea, retaining its basic characteristics (U.S. Navy Hydrographic 

 Office, 1962). Some of this water moves into the Ross Sea, penetrating 

 to nearly every part of the area. The Antarctic Circumpolar Water, though 

 modified by mixing with the upper and shelf water masses in the Ross Sea, 

 is still recognizable by relatively high temperatures and low oxygen 



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