low temperature. Thus, in the areas of contact of these waters with the denser ocean water, con- 

 vection currents are set up. Due to local conditions (i.e. , shallow depths), such currents are 

 absent in the Bering Straits and in the straits of the American archipelago, nor in the straits which 

 connect the Arctic Basin with the Barents Sea are they considerable. They are sharply expressed 

 (again due to local conditions) only between Greenland and Spitzbergen (due to presence of great 

 depths and saline Atlantic water) . Unfortunately it is not yet possible to show the significance of 

 convection currents in the Arctic Basin. 



A third factor which determines the general circulation in the Arctic Basin is wind conditions. 

 Wind behavior is connected with the distribution of pressure and experience seasonal and long 

 term variations. It is clear that the general circulation is determined not by local or short-lived 

 winds, but by the distribution of winds over the whole Arctic Basin and over the ocean basins com- 

 municating with it. 



So, the general circulation of water and ice in the Arctic Basin is extremely complex. In it 

 the drainage circulation, convective circulation and wind-drift circulation are superimposed one on 

 the other. 



It is characteristic of the Arctic Basin that the drainage and convective circulations are set 

 up in the water masses and are transmitted to the ice. The wind-drift circulations are transmitted 

 from the ice to the water masses. But in every circulation of water masses, in addition to the 

 horizontal, there are also vertical components which are particularly pronounced in areas of sink- 

 ing and rising. Since the vertical components are absent in the movement of ice, the circulation 

 of ice is different in this respect from the normal circulation of water masses. 



As we have seen, the coastal drainage of rivers which drain into the Arctic Basin diminishes 

 in the direction west to east. The total coastal drainage of the Asiatic coast is equal to 2, 500 to 

 3,000 cubic km per year. A second peculiarity of the coastal drainage is the variability of its 

 quantity from year to year. The third and most important peculiarity of the coastal drainage of 

 Asiatic rivers is its sharply defined seasonable quality. 



The intensity of the coastal drainage in the summer season is of great importance for navi- 

 gation along the arctic coast. Due to the drainage, the arctic ice not only melts intensely in the 

 summer season but also moves away from the coast. The greater the drainage, i.e. , the more 

 westerly, the more distinct this phenomenon. The drainage also moderates the unfavorable effect 

 of monsoon winds which flow from land to sea in the winter and from sea to land in the summer. 



It has already been pointed out that with our level of knowledge it is impossible to determine 

 the role of purely convective currents in the general circulation of water and ice in the Arctic 

 Basin. Existing observations make it possible, but only extremely roughly, to calculate the water 

 exchange through the main straits which connect the Arctic Basin with adjacent basins. 



Thus, in June, July and August the flow into the Chuckchee Sea through Bering Straits com- 

 prises, according to Ratmanov, approximately 95 per cent of the whole water exchange between the 

 Arctic Basin and the Bering Sea. The speed of the surface current reaches 3 to 3. 5 knots. The 

 east-west cross section area of the straits is about 2.5 square km. Assuming the average speed 

 of the Pacific current (increasing in summer and decreasing in winter due to the development of the 

 Aleutian low pressure cell) at about one km per hour, we find that the influx of Pacific water through 

 Bering Straits can not exceed 20,000 cubic km per year. The Pacific current in Bering Straits is 

 not a convection or drift current. It is a compensation current caused by the flow of water from 

 the Arctic Basin into the Greenland Sea. 



400 



