Ice in the Sea 



267 



July. At the end of October, and during the first half of November, ice formation 

 begins again along the northern coast. Conditions here are quite different from those 

 along the east coast of North America and Greenland since the ice masses in these 

 adjacent seas of eastern Asia are always of local origin, and are not reinforced by 

 Arctic pack ice and icebergs as in the East Greenland and Labrador Currents. 



Knowledge of the annual variations of the ice coverage in the ocean surrounding 

 the Antarctic is still very poor. The ice limits in each month have only been known with 

 some accuracy since the intensification of whaling. The pack ice limits in the Ant- 

 arctic between 40° W. and 1 10° E. have been given by Hansen (1934) for the 4 years 

 from 1929 to 1934 (Fig. 122). In the area east of South Georgia to about 20° E. the 



Fig. 122. Pack ice limits in the antarctic region between 40° W., and 1 10° E., for the whaling 

 season 1930-1 (according to Hansen). 



ice extends to a latitude of about 55° S. at the beginning of November. Deviations 

 from this value in the course of the year are small. East of 20° E. the limit trends 

 more and more to the south. As the season advances this outer pack ice retreats 

 slowly towards the south, and by December whaling ships can penetrate it and reach 

 open water at about 60° S. There is then usually no pack ice until the inner pack 

 ice coast is reached. 



These two ice zones, the inner drifting westwards and the outer eastwards, are 

 characteristic for the whole region from the Weddell Sea as far as 20-30° E. They are 

 about 7° lat. apart. There is no such subdivision in the ice drifts east of Enderby Land. 

 The outer pack ice zone melts very rapidly, especially if it is broken up in a number of 

 places into large drifting ice masses. In the region of the Antarctic Ocean from 

 Enderby Island and Balleny Island the ice limit retreats steadily during the melting 

 period; the oceanic currents directed northward (equatorward) in 60° S. carry the 

 ice floes in the same direction whereupon they rapidly disperse and melt. 



