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General Characteristics of the Northern Seas 



I. HYDROLOGICAL CONDITIONS 

 The link with the Atlantic and the Pacific Oceans 



The Arctic Ocean is sometimes regarded as a kind of Inter- American-Eurasian 

 Mediterranean Sea (North Polar Sea) which forms a supplementary body of 

 water for the Atlantic Ocean. The Arctic Ocean is, however, so much a 

 separate body of water with its own characteristic and independent climatic 

 and hydrological conditions, that it can be considered as an independent 

 ocean. 



Nevertheless, this is not to deny that the Arctic Ocean and its fauna are at 

 the present time exposed to the continuous and very powerful influence of the 

 waters of the Atlantic Ocean, and to the comparatively insignificant influence 

 of the waters of the Pacific Ocean. 



The cross section of the Bering Strait is only 2-5 km 2 while that of all the 

 straits between Greenland and the Scandinavian Peninsula is about 370 km 2 . 

 The maximum depth of the Bering Strait is 70 m but the minimum depth of the 

 submarine ridge between Greenland and Scandinavia is about 440 m. 



Approximately 8,000 km 3 of water (Kort, 1962) enter the Arctic Ocean 

 annually through the Bering Strait, but no less than 400,000 km 3 of Atlantic 

 waters enter the Arctic Ocean from the south. No less than 436,300 km 3 of 

 water are carried out by the Arctic currents into the Atlantic Ocean includ- 

 ing approximately 6,000 km 3 in the form of floating ice. Thus the Arctic 

 Ocean exercises a great influence on the Atlantic Ocean and on the climate 

 of North America. The amount of heat brought into the Arctic basin* 

 with the warm Atlantic waters is enormous. The heat liberated by cooling 

 these waters merely by Г would be sufficient to raise the temperature of a 

 4 km layer of air over the whole of Europe by 10°. 



The warm Atlantic waters, acting as a special kind of heating system, heat 

 the Arctic and bring warm- water fauna far to the northward. 



The surface layer of water with a lower salinity and the great extent of 

 floating ice, which in winter is about 1 1 x 10 6 km 2 , and in summer about 

 8x 10 6 km 2 (60 to 80 per cent of the total surface), cover the warm Atlantic 

 waters like an insulator, and the thermal action of these waters is felt at a 

 depth of 300 to 900 m. 



As will be shown below, the nature of the interaction of the faunas of the 

 three oceans, the strong influence of the faunas of the Atlantic and Arctic 

 Oceans upon each other, and the slight interaction between the faunas of the 

 Arctic and Pacific Oceans, are completely in keeping with the systematic inter- 

 change of water between the Arctic and its two neighbouring oceans. 



This, however, is only true, of course, for the position at the present time. 



* The expression Arctic basin is commonly used, and we shall use it here in the same 

 sense as the North Polar Ocean. 



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