d. Dissolved Oxygen 
On the west-east profiles, oxygen minimum values were found at the 
bottom on the sections over the continental shelf. The oxygen minimum layer within 
the Circumpolar Water was located between 500 and 600 meters, just above the depth 
of the salinity maximum and at about the same depth as the temperature maximum. 
The north-south profiles show an oxygen minimum layer of less than 4.50 ml/I ina 
broad zone generally between 400 and 1,200 meters, extending from the north to the 
continental shelf. This pattern of oxygen distribution provides supporting evidence 
for the circulation derived by dynamic topography. 
3. Dynamic Topographies 
In order to draw dynamic height charts (Figs. 9 and 10) of the Eastern Ross 
Sea area and include data for the majority of stations, it was necessary to select a 
reference level of 200 decibars. This is not a level of no motion, nor is it a level 
of oxygen minimum, but it does permit an estimation of circulation in the area. Prior 
to selecting the 200 decibar level as the reference level, other levels (500, 1000, and 
1500 decibars) were used as a reference level. In each case, the same general circu- 
lation pattern was apparent; that is, a seaward flow to the east of Edward VII Peninsula, 
a shoreward flow to the west of Edward VII Peninsula, and a west-to-east flow about 
150 miles north of the shoreline. Maximum current speeds were found at the surface 
which decreased in intensity with depth. 
On the west side of the area, a large clockwise circulation is apparent, which 
probably was induced by combined effects of the eastward flowing Circumpolar Water 
and the prevailing winds. This current pattern reached to station 7, approximately 
165 miles seaward, from the edge of the Ross Ice Shelf and Cape Colbeck and decreased 
in magnitude with increasing depth. At the 150-decibar level, it extended about 100 
miles from the Ross Ice Shelf. Current speeds ranged from 0.3 knot at the surface to 
0.1 knot at the 150-decibar surface; not only did the speed decrease to 0.1 knot at 
this level, but a weak counterclockwise component appeared at the northwest corner 
of the area. 
To the west of Guest Island, a seaward flow is found at all levels with speeds 
also ranging from 0.3 knot at the surface to 0.1 knot near the bottom. Two components 
of this flow were noted from the O- to 50-decibar levels; an eastern component forming 
a weak clockwise circulation and a western component forming a major counterclockwise 
current around Cape Colbeck. From the 100- to 150-decibar levels, the apparent flow 
was to the west as a counterclockwise current. The clockwise circulation weakened 
and disappeared at these levels. 
