Ice in the Sea 

 Table 99 



261 



groups, sometimes associated with icebergs which were formerly frozen into them. 

 South of 64° S. begins the continuous drift ice which is held together by the westward 

 directed currents which tend to the south due to the influence of the Coriolis force. 

 Icebergs are more frequent here and have the table-form characteristic of the Antarctic. 

 The ice masses are driven together partly by the wind, but the ice pressure is not as 

 strong here as in the Arctic, The belt of drift ice extends to the edge of the continental 

 shelf. 



In the shelf zone over the shallow waters the ice is a mixture of floating ice floes and 

 icebergs which form here and accumulate. The whole mass is held together by the 

 larger icebergs stranded in shallow water. Superficially the shelf ice appears as a 

 flattened, smooth, rounded ice-surface because of the frequent snow storms, but if 

 the upper parts of the ice is broken off by the wind, the solid ice layers stand out more 

 clearly; these have been termed blue ice by Drygalski on account of their colour. This 

 permanent region of shelf ice between the drift ice and the coast completely surrounds 

 the coast and obhterates the actual coast-line. This is the main cause of the uncertain 

 charting of the Antarctic continent. 



There are only a few approximate estimates of the budget of ice transport of the 

 total polar regions. Krummel (1907, p. 515) gave the following approximate summary 

 for the Northern Hemisphere: between Spitzbergen and Greenland the main carrier 

 of outflowing sea ice is the East Greenland Current. It has a width of about 500 km, 

 and according to Makaroff" in summer and winter about 76% of its surface is covered 

 with ice floes and pack ice. Taking the mean velocity of the current as about 10 

 nautical miles a day and the average thickness of the ice as 5 m then the annual 

 volume of ice carried out from the central Polar Basin by the East Greenland Current 

 will be 12,700 km^. This is about one-third of the total pack ice and polar ice in 

 the entire North Polar Basin. Another stream of ice floes comes from Baffin Bay. 

 This has a width of 200 km when leaving Davis Strait and on the same basis as before 

 will carry somewhat more than 5000 km=^ a year. If, furthermore, the drift ice entering 

 the Barents Sea is estimated as 2000 km^, there must be a total annual flow of about 

 20,000 km^ of ice to be melted in the northern part of the North Atlantic each year. 



{b) Seasonal Displacements of the Ice Limits 



The inner part of the North Polar Basin is covered by polar ice throughout the year 

 and changes appear only at the edges in the outer ice zone, especially near land areas. 



