II. ROSS SEA ABEA, OCEANOGR/LPHr 



A. General 



The Ross Sea is fonned by a deep linpression into the Antarctic 

 Continent between 160° W, and 160° E, The eastern side is fonned 

 by the Edward VII Peninsula with Cape Colbeck at its most northern 

 tip, to the west it is boimded by Victoria Land which terminates to 

 the north at Cape Adare. The Ross Sea is approxitnately 500 miles 

 broad and some 700 miles deepj the southern half of the sea is com- 

 pletely filled by shelf ice, the famous Ross Shelf Ice forming the 

 Ross Ice Barrier which extends for I4.OO miles along its northern edge. 

 The Ross Ice Barrier extends from McMurdo Sound and Ross Island east- 

 ward to Okuma Bay and Edward VII Peninsula and continues as the ice 

 shelf along the peninsula around Cape Colbeck, 



During the x*inter months (June through August), the Ross Sea 

 freezes over but as spring and summer approach, southerly winds and 

 currents break up the fast ice and push it to the north. During the 

 .summer months (December through February), there is always a wide 

 belt of ice-free water extending from the shelf ice face northward 

 about one hundred miles to the edge of the pack. The pack extends 

 northward to just south of Scott Island and is variable in its extent 

 and consistency from one season to another. In some rare summer 

 seasons, ships have not encountered any pack ice along the 180° raeri- 

 dianj at other times pack ice presents a formidable barrier across the 

 entrance to the southern part of the Antarctic seas. By January, in 

 typical seasons, the Icepack is broken, rotten, and easily traversed 

 by modern, powerful ships. The open water along the face of the Ross 

 Ice Shelf commonly continues northward along Edward VII Peninsula as 

 far as Cape Colbeck, In some seasons a lead of open water extends 

 eastward from Cape Colbeck for a considerable distance along the 

 coast of Marie Byrd Land, 



The Ross Sea averages 500 to 1,000 meters in depth and its waters 

 are cut off from the open ocean by the Pennell Bank, which is con- 

 siderably less than 500 meters deep and effectually retains bottom 

 water to the south, Ifence there is no cold bottom current running 

 out of the Ross Sea such as we have in the Weddell Sea, Outside of 

 the Ross Sea to the north, the general surface current trend is from 

 west to east, A westerly setting current runs along the ice she3jffface 

 and out along the coast of Victoria Land and around Cape Adare. This 

 current has a drift amounting to as much as 3 knots along the Ross Ice 

 Shelf, In general, the Antarctic surface water is cold to a depth of 

 100 to 250 meters and lies on top of a warmer, more saline layer. Near 

 the ice in the summer months considerable variation in salinity and 

 temperature occurs, which is caused by melting ice. 



