Ice in the Sea 



263 



The solid ice of the coastal shelf shows particularly a pronounced annual variation 

 since it melts away almost completely during summer and re-forms again during the 

 autumn. The North European and Siberian Shelf areas thus show large seasonal 

 displacements in the ice limits. In the eastern part of the Siberian sea-way east of 

 Novaya Zembla and remote from the influence of the North Atlantic current the 

 distribution of ice, even in the summer months, may change so rapidly and so much 

 that it is difficult to give exact mean ice limits for individual months (see Atlas der 

 Deutschen Seewarte, 1942; BiJDEL, 1950; Nusser, 1952). 



In the Barents Sea, which is particularly influenced by the Atlantic Current, the 

 seasonal displacements of the ice limit are very large. The two small charts in Fig. 



117 present the mean ice limits as separate monthly means for a 10-year period from 

 1929 to 1938. One of them (March to August) shows the retreat of the ice limit in 

 spring and summer, and the other (September to February) shows its ad\ance in 

 autumn and winter. During tliis period from 1929 to 1938 ice conditions were par- 

 ticularly favourable and this should be borne in mind. 



The monthly limits of the ice along the eastern coast of Greenland, in the Davis 

 Strait, in the Baffin Bay and along the east coast of North America as far as the Grand 

 Banks of Newfoundland are almost entirely within the region of inffuence of the two 

 great polar currents, the East Greenland Current and the Labrador Current. Figure 



118 shows two charts, again for the period of retreat (March to September) and ad- 

 vance (September to February) (see also Atlas der Deutschen Seewarte, 1940, means 

 for the years 1929-38). The east coast of Greenland is blocked for almost the whole 

 year by a belt of ice varying strongly with latitude ; this coast is only free of ice in the 



^ 50° 40° 60° Vl/ 



Fig. 118. Average ice limit along the eastern coast of Greenland, in Davis Strait and Baflfin 

 Bay, and along the east coast of North America for each month (1929-38). 



