Ice in the Sea 283 



results (Defant, 1933). The formation of the East Greenland Current and the main- 

 tenance of its polar character as far as Cape Farewell is not due to melting processes ; 

 its Arctic nature is mainly acquired from its direct connection with the North Polar 

 Basin causing a continuous supply of polar water and from the climatic conditions 

 maintained over Greenland by the inland ice. This advective supply of Arctic water 

 from areas where the effect of solar radiation is very small is the determining factor, 

 and sea ice and icebergs are only accessory phenomena. 



A marked effect of the ice masses of the polar seas on the atmospheric circulation 

 has been assumed by many prominent meteorologists. Hildebrandsson (1914) 

 especially has attempted to show that the cause of the secular variations in meteoro- 

 logical factors is to be seen in the aperiodic variations in the amount of polar ice. 

 More recent data from later investigations has lent support to this hypothesis, but a 

 definite proof is difficult. Both phenomena are not independent of each other, so that 

 it is reasonable to assume, of course, a mutual interaction between the ice conditions 

 and the atmospheric circulation; it is not easy to separate cause and effect (Wiese, 

 1924). Conditions are probably such that variations in the atmospheric circulation 

 change the equilibrium conditions in the polar reservoirs of cold air. Years with 

 weaker circulation favour an increase in the thickness of the cold air masses in the 

 polar regions. This increases the atmospheric pressure in the polar region and corre- 

 spondingly winds and currents become stronger, which causes a greater extension of 

 the polar ice towards the south. The increased ice surface in turn increases the air 

 pressure; the atmospheric pressure anomaly thus acquires a certain permanence, and 

 due to this mutual reinforcement the effect may last a long time. The atmospheric 

 pressure in the polar areas is thus a very sensitive indicator of the general condition 

 of the atmosphere. Since, however, the atmospheric pressure conditions in these re- 

 gions is reflected in the ice conditions, the distribution of ice in the polar seas can be 

 taken as a measure of the variations in the general atmospheric circulation, provided 

 sufficiently accurate information is available. 



The major variations in the atmospheric circulation usually extend throughout 

 the entire atmosphere over the whole Earth, both in the Northern and Southern 



Table 109. Parallelism between changes in ice conditions of the north 



and south polar regions 

 Shown by the relation between ice conditions from March to May at the South 

 Orkney Isles (years with close or open ice) and corresponding deviations of the 

 ice coverage in May to August from an average value of the period 1896-1916 



in the Barents Sea 



South-Orkney-Isles 



Character of ice 



conditions for March 



to May 



Close ice 



{ 



Open ice . . . .■! 



Barents Sea 

 deviations of the ice coverage (in 1000 km^) for May to 

 August from an average value of the period 1896-1916 



1903 1909 1910 1911 1912 



+88 +102 +17 +97 +176 (above average) 



1904 1905 1906 1907 1908 

 -158 -165 -61 -130 -121 (below average) 



