III. ROSS SEA AREA, OCEANOGRAPHY 



A. General 



The Ross Sea lies south of the Pacific Ocean between 160°E and 

 150°W, It is a large open body of water with depths generally less 

 than 400 fathoms and with free circiilation to the circumpolar ocean 

 waters to the north. 



To the south, the sea is bounded by the floating seaward margin 

 of the Ross Ice Shelf. ^lany glaciers and small ice shelves extend 

 along its margins, but in spite of this, a relatively large percentage 

 of land is exposed during the summer season. Sea ice forms during the 

 autumn and winter seasons, but usually breaks up sufficiently in late 

 summer to permit ship transit to all corners of the sea. A general 

 east to west set removes much of the ice and bergs, but some are confined 

 in a gyral in the northern portions of the sea. 



B, Physical Properties 



Fifteen oceanographic stations were taken across the convergence 

 and in the Ross Sea (Figs. 5, 6, and 7). Of these, GLACIER stations 

 3 thro\jgh 6 (Fig. 5) taken in November, provide the only usable section 

 for oceanographic description. The stations taken in McMurdo Sound 

 and Kainan Bay are similar to those discussed in the DEEP FREEZE I 

 report .■*^" 



1, Temperature 



The thermal structure of the Ross Sea in early November probably 

 represents a relatively unmodified winter condition. The surface area 

 of the section was covered with sea ice and surface temperatures held 

 close to -loQoC. The water in these moderately shallow depths is 

 essentially isothermal except at the northern station (GL-6) where 

 a warm tongue with maximum temperatures greater than 0.8°C at 200 

 to 250 meters intrudes (Fig. 8), This is the southern extent of the 

 main part of the Antarctic Circ\jmpolar Watero This water shows up 

 again at station GL-4, with a maximum temperature of -0,4°C at 200 

 meters. This is either a partially mixed-out discontinuous extension 

 of the Antarctic Circumpolar Water, or perhaps the southern arm of 

 a subsirrface gyral of this water in the Ross Sea, 



* H. 0. I633I-I, U. S. Navy Hydrographic Office Report on Operation 

 DEEP FREEZE I, Oct. 1956, U. S. Navy Hydrographic Office, Washington, 

 D. C. 



13 



