of the others. 



The isolines of temperature and salinity continue to run 

 approximately parallel to the Alaskan coast, with the warmer, 

 less saline water near the coast. This distribution breaks 

 down near the ice pack, where cold but low-salinity melt 

 water complicates the picture. 



Sverdrup had indicated that the northward flow of water 

 through Bering Strait continued only at subsurface depths in 

 the Chukchi Sea in summer, with a return current southward 

 along the surface related to the prevailing northwest winds. 

 A detailed study of the temperature-salinity relationships, 

 and of the dynamic topography, observed on the NEREUS 

 cruise, indicates, however, that in 1947 the flow in the central 

 Chukchi Sea was northward at all depths as far as station 

 N14, slightly north of 70°N. At this point there is evidence 

 of cold, low-salinity melt water related to the melting of the 

 ice. This water has apparently drifted southward from the 

 ice region under the influence of the north-northwest wind 

 prevailing at the time. 



At the stations north of 70°N a very characteristic bottom 

 water was found. This water was relatively cold and saline, 

 and is apparently the result of the winter freezing. Between 

 the cold, low-salinity melt water at the surface and the cold, 

 high-salinity bottom water the relatively warm, moderately 

 high-salinity water from the south enters as a wedge. The 

 cold, high-salinity bottom water is probably formed both in 

 the Chukchi and Bering Seas to the southern limit of the 

 winter ice formation. Its appearance only north of 70°N on 

 this cruise indicates that it has been displaced by the north- 

 ward flowing water from the Bering Sea through Bering Strait. 

 This is further substantiated by the fact that more recent ob- 

 servations, not yet reported on, show that this characteristic 

 bottom water was not in evidence as far north as the edge of 

 the ice pack in the summer of 1948. This finding indicates 

 that this bottom water has been completely displaced from 

 the shallow shelf region of the Chukchi Sea. 



The presence of this peculiar layering of the various 

 types of water in the northern Chukchi Sea during the cruise 

 of the USS NEREUS caused very unusual vertical temperature 

 structures. The cold surface layer is followed by a sharp 

 positive temperature gradient, below which occurs the negative 

 gradient separating the bottom water from the intruding 

 warmer water originating to the south. These positive gradi- 

 ents present important problems from the standpoint of under- 

 water sound transmission. 



