In the final result, for the European- Atlantic sector of the arctic , the various combinations of 

 mutual action of atmosphere and hydrosphere along the routes of the Atlantic water have their effect 

 on the location of paths of cyclones which arise in the region south of Iceland and have an effect on 

 the intensity of atmospheric circulation. Seherhag shows, for the period 1921 to 1930, that the Ice- 

 land and Aleutian lows deepened by almost 5 mb in the winter, while the pressure in the whole sub- 

 tropical zone increased (figure 189). The transfer of polar maritime air from the Atlantic into 

 Barents Sea increased in accordance. 



Figure 189. Anomalies of atmospheric pressure for 10 year period 

 from 1921 to 1930 (in mb) according to Seherhag. 



On the other hand, the warmer Atlantic waters themselves and the absence of ice bring about 

 an increase in atmospheric circulation, and the cyclone paths accordingly run further north. More 

 northerly cyclone paths create warmer conditions in the European- Atlantic sector of the arctic. 



LITERATURE: 29, 49, 77, 99, 100, 161, 162, 170. 



Section 161. Synoptic and Oceanographic Factors 



We have already seen that as a general rule the ice abundance of a given region is a combina- 

 tion of the ice abundance due to local ice and that due to ice exchange with adjacent seas. The ice 

 abundance due to local ice depends on: 



1. Meteorological conditions (in the broadest sense of the term) in the period of ice formation 

 and melting. 



2. Water exchange with neighboring seas insofar as this water exchange exerts an influence 

 on temperature conditions of the sea. 



Since meteorological conditions and water exchange vary from year to year within fairly wide 

 limits, it is therefore natural that ice conditions should also vary considerably. What is more. 



464 



