200 meters in the Cape Colbeck area. Temperatures were about -1.75°C, and salinity 
values ranged from 34.00 to 34.40%. Oxygen content appeared quite uniform, ranging 
from 6.25 to 6.65 ml/1. 
Below the Antarctic Winter Water, a second transition layer extended to the 
Antarctic Deep Water. This was indicated by a steep positive gradient in the temper- 
ature profile and a steep negative gradient in the oxygen profile. The depth at which 
this transition layer was found varied considerably in the different areas. North of 
Amundsen Sea, about 70°S, this layer was between 100 and 200 meters; whereas, in 
the Cape Colbeck area, about 75°S, it was observed at greater depths, between 250 
and 450 meters. Between these two latitudes, it was located at intermediate depths. 
The temperature increase for all areas was approximately 2.5°C, from about -1.50 
to 1.00°C; the salinity increase was of the order of 0.5%,, from 34.20 to 34.65%; 
and the oxygen decrease was approximately 2 ml/I, from around 6.3 to 4.2 ml/1. 
Immediately below this transition layer were found maximum temperature, salinity, 
and minimum oxygen values. This Antarctic Deep Water is referred to in this report as 
Antarctic Circumpolar Water, with the area of maximum temperatures and minimum 
oxygen concentrations identifying its core. As shown by the t-s and vertical distribu- 
tion plots, maximum temperatures for the different areas vary from | to 2°C, generally 
being about 1.68°C at 400 meters in the Amundsen Sea area, 1.45°C at 600 meters 
in the Cape Colbeck Area, and about 1.10°C at 500 meters in the Bellingshausen Sea 
area. Maximum salinities, ranging between 34.70 and 34.759, were found somewhat 
deeper, in the vicinity of 800 meters. Minimum oxygen values were slightly greater 
than 4.00 ml/I at about the same depth as maximum temperatures. Between 500 meters 
and bottom, little change in observed physical and chemical properties existed on all 
the stations occupied. Representative station profiles in Figure 24 show that between 
500 and 3,000 meters temperature decrease did not exceed 1.2°C, salinity decrease 
was less than 0.1%,, and oxygen increase was less than 0.75 ml/I. 
Considering Antarctic Bottom Water to have temperature and salinity values less 
than 0.5°C and 34.7%,, respectively, Figure 24 does not indicate Bottom Water in 
these areas; however, these conditions were observed on some stations around 3,000 
meters, and below. 
F. Antarctic Convergence 
1. General 
The Antarctic Convergence is considered as the zone where the cold and 
more dense surface water to the Antarctic region sinks below the warmer and less 
dense surface water of the north. This zone is marked usually by a sharp north-south 
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