II. WcDDELL SEA ARSA, OCEANOGRAPHY 



A. General 



The perimeter of the Antarctic Continent is indented by two great 

 seas, the Ross and Wsddell. The Weddell Sea lies south of the western 

 South Atlantic, and differs principally from the Ross Sea in two ways; 

 (l) it has areas of great depths, and (2) it is bounded on the west 

 by the most northerly extension of Antarctic Land, the Palmer Peninsula. 



The southerly end of the Weddell Sea is covered with a great ice 

 shelf (Filchner Ice Shelf), and the actual shoreline beneath this ice 

 is unknowi at present. Various glaciers and ice shelves also extend 

 along the eastern and western sides of the sea, so that the percentage 

 of exposed or nearly exposed land at sea level is at a minimum. 



The sea itself is generally ice filled, even in summer months, 

 and the current pattern (clockwise, with water entering at the north- 

 east) plus the prevailing winds seem to pack the ice along the western 

 side. This wind and current action makes ship entry possible along the 

 eastern side, although changes in local winds may close leads tempor- 

 arily. Until Operation D£ZP FRZSZE II, no ship had ever penetrated to 

 the southwest corner of the sea. However, the U53 STATEN IdLANC, 

 followed by the cargo ship U53 aYAIwOT, was able to penetrate to within 

 about forty miles of the southwest comer d-oring the month of January. 

 This was accomplished despite severe setbacks by increased ice pressure 

 during periods of northerly winds. 



B, Physical Properties 



Twenty-six oceanographic stations were taken along the ship*"s track 

 (Fig. 2). Five stations were also taken off the west coast of Chile, 

 and although all station data are presented in Annex C, these latter 

 stations are out of the area and will not be discussed. 



1. Temperature 



During the December crossing cf Drake Passage, water temperature 

 north of the Antarctic Convergence decreased gradually wdth depth 

 (Fig. 3). South of the convergence, temperatures decreased wi.th depth, 

 except for a thin isothermal surface layer, with a minimum reached at 

 about 200 to 400 meters. Increases were noted as the warm, deep water 

 was encountered. F'urther south (Station 3. 1. -7) the summer warming 

 of the surface layers was proporticnately less as the edge of the ice 

 pack was approached. Here, the minimum temperat\ire remnant was found 

 at about ninety meters depth, with more gradual wanning below. Ob- 

 servations on these stations were not deep enough to encounter the 

 cold Antarctic Bottom /feter. 



