homogeneous from top to bottom. It may have its 

 origin in mechanical mixing over the bottom rise in 

 that area. It further appears to be renewed by 

 mixing between Alaskan Coastal Water and Modi- 

 fied Shelf Water. 



In the Chukchi Sea region it would be antici- 

 pated that the run-off of the rivers along the north 

 Siberian coast would create a coastal current moving 

 southward along the western side of Bering Strait 

 as a counterpart to the northward flow of Alaskan 

 Coastal Water. Such a current was not found in the 

 Bering Strait, nor was it indicated by the observa- 

 tions of USCGC CHELAN in 1934 5 or the NORTH- 

 LAND in 1937 or 1938.° Thus, it appears that the 

 low-salinity cool water found directly north of Bering 

 Strait to the west of Kotzebue Sound is the Siberian 

 coastal current which has been diverted by the 

 strong flow through Bering Strait and is carried 

 northeastward away from the coast. This mass of 

 Siberian Coastal Water, which moves out of the 

 surveyed area, with time and displacement would 

 tend to lose its identity because of mixing. The Modi- 

 fied Ice Melt water also moves west and southwest 

 out of the area surveyed. It is possible that some of 

 this water moves southward in the region of Wrangel 

 Island and combines with the flow of Siberian 

 Coastal Water to set up a weak cyclonic gyral 

 between Wrangel Island, the Siberian Coast, and 

 the region near Herald Shoal. 



The shallow Bering and Chukchi Seas thus form 

 a coastal system with a general structure which is 

 consistent from year to year. The water masses are 

 derived from four distinct sources, Alaskan coastal 

 drainage, Siberian coastal drainage, freezing of 

 the ice in winter, and melting of the ice in summer. 

 The other water masses are modifications of these, 

 two arising from heating effects and the third from 

 a mixing between water masses. 





Figure 7. Surface currents in the eastern Bering Sea and the 

 eastern Chukchi Sea. Surface current arrows indicate only ap- 

 proximate strength and persistency of current. 



19 



