m mimm iWiJiu 



m 



m? 3 5 7 9 n 13 15 17 J9 21 23 25 27 23 31 33 



Figure 188. Graph of comparative ice-abundance in the Kara Sea (upper 

 curve) and in the sea east of the Kolyma River (lower curve) . 



Chuckchee Sea, that is, low ice quantity in the Kara Sea corresponding to high ice quantity in the 

 Chuckchee Sea and vice versa, is quite evident. 



I, personally, have not been able to note a periodicity of short cycles in my investigations 

 into the ice abundance of seas of the Soviet Arctic. 



LITERATURE: 22, 32, 34, 77, 78, 119. 



Section 157. Certain Factors which Determine the Ice 

 Abundance of the Arctic Ocean 



We may conditionally divide into several groups the factors which govern the ice abundance of 

 the Arctic Ocean. Some of these may act in the same direction over very long time intervals and 

 are connected with world-wide variations in climate. To this group belong astronomical and geo- 

 logical factors. A second group acts over a series of years and sometimes over scores of years 

 and is connected with climatic fluctuations. To this group belong temporary changes in the general 

 circulation of the atmosphere and hydrosphere over the entire globe. Finally, a third group con- 

 sists of factors which change the ice abundance from year to year. To this group belong the tem- 

 porary changes in circulation of atmosphere and hydrosphere in the Arctic Basin itself and in the 

 atmospheric and oceanic centers of action which exert the greatest influence on conditions in the 

 Arctic Ocean. The last group of factors is obviously of the greatest practical interest. We must 

 not forget, however, that fluctuations in ice abundance from year to year are superimposed on a 

 definite background created by factors acting over great time intervals . 



Also we must not forget the influence of the ocean which smooths out the sharp fluctuations of 

 atmospheric conditions. This remark refers particularly to the influence of extensive, deep and 

 uniform ocean regions, since it is only in such regions that quantities of heat are absorbed or given 

 off which are sufficient for an essential change in synoptic processes. An example of this is the 

 Atlantic (Gulf Stream) current and its offshoots, meeting all the above-listed conditions. 



LITERATURE: 77. 



Section 158. Astronomical Factors 



Of the astronomical factors which exert an influence on ice abimdance, of greatest interest 

 are the variations in the sim's activity which are connected with the 11-year sun spot period and the 

 periodic variations in mutual relations of the earth, moon and sun. 



459 



