IV. VBICENNES BAY, OCEANOGRAPHY 



A, General 



Vincennes Bay lies betv;een the Budd and Knox coast at about 110°E. 

 The water of Vincennes Bay is comparatively shallow as far north as 

 about 65°S where the continental slope drops off rapidly into deep 

 water. Most of the bay is apparently shallower than 500 fathoms, 

 although very few sounding lines have been rvn to date. Vincennes 

 Bay normally appears to be ice free during the summer season, except 

 for some grounded bergs. During periods of northerly gales, it may 

 contain heavj ice pack as late as early February. This was the case 

 in late January 1957, but three weeks later the pack ice had largely 

 disintegrated or moved northward. 



The USS GLACIER was in Vincennes Bay from 25 January to 17 Febru- 

 ary 1957. During the period from 31 January to 17 February, a reconnais- 

 sance run was made north as far as about 65°S to observe ice conditions 

 and occupy oceanographic stations, 



B. Physical Properties 



Station GL-8 was taken off Clark Island (Windmill Islands) in 

 shallow water; stations GL-9, GL-10, and GL-11 were occupied one week 

 later in a line extending south from 65°20'S along 109°E (Fig. 5). 



1. Temperature 



Temperatures of these four stations off Vincennes Bay were 

 relatively cold at all depths of measurement (Fig. 9). A slight simmer 

 surface warming was most noticeable at the shallow station, GL-8, 

 probably resulting from coastal leads permitting greater insolation of 

 the water thus exposed. 



The small temperature inversion recorded at shallow depths on 

 stations GL-8 and GL-10 are probably due to pack ice belts recooling 

 surface water after initial warming by insolation. Vflien leads develop, 

 insolation warms the surface, causing a temperature inversion at 

 shallow depths. These inversions are often stable from a density 

 viewpoint because of the lowering of salinity at the surface. How- 

 ever, if refreezing occurs, the inversion may not be stable. 



An interesting illustration of this occurred during an ocean- 

 ographic station occupied during March 1956 (GL-12), discussed in the 

 DEEP FREEZE I report. This station was taken -under freezing conditions, 

 with ice crystals forming on the surface. This caused surface tempera- 

 tures to drop to below -2.0°C and the inversion was considered tempor- 

 ary and unstable. When compared to station GL-9 (Operation DEEP 

 FREEZE II), it is obvious that the water stabilized through vertical 

 mixing (Fig. 10). 



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