Figure 8b. Circulation of 150-meter 

 level computed relative to the 500-meter 

 surface. Dynamic height anomaly ex- 

 trapolated into shallow water at sta- 

 tions 2 and 30. 



dent from their closely spaced observations, but 

 masked by the more general circulation obtained by 

 our more widely spaced observations. The higher 

 east and northeasterly speeds observed near the 

 islands by Barnes and Thompson are in good agree- 

 ment with our observations, as these would be re- 

 quired by continuity to supply the water for the 

 northeasterly flow. 



Our observations do not extend far enough to 

 the northwest to verify or contradict the northeasterly 

 flow from west of the Near Islands to St. Matthew 

 island. If the earlier proposed circulation of the 

 water creating the temperature minimum is assumed 

 to be correct, some doubt is cast upon the validity 

 of any appreciable northeasterly surface current in 

 the central deep Bering Sea because a large velocity 

 shear would have to be present between 150 meters 

 and the surface. It seems more likely that the greatest 

 shear would exist at the interface between surface 

 layers and the subarctic Pacific water which is at 

 200 to 300 meters. It would appear that there is no 

 appreciable surface current in the central deep 

 Bering Sea, but that an extremely slow drift of water 

 to the northeast might occur at levels between 300 

 and 1000 meters. Thus the surface inflow of Pacific 



water through the passes of the eastern Aleutian 

 Islands, plus the deep inflow between the Koman- 

 dorski and Near Islands, and the river inflow would 

 have to balance the outflow of the northerly current 

 through Bering Strait and the Oyashio current. A 

 future extension of observations northwestward to 

 the International Boundary, or to the Siberian con- 

 tinental shelf, if possible, seems necessary to resolve 

 this question. 



SOUND VELOCITY 

 surface layers 



Of all oceanographic factors, probably the most 

 important, role is played in military operations by 

 the sound-velocity structure in the surface layer. 

 Generally speaking, the sound-velocity structure in 

 the surface layer is subject to diurnal effects and 

 short-period variations of less than a month because 

 of the influence of atmospheric conditions. In the 

 Bering Sea in summer, the diurnal effects are nearly 

 negligible because of the persistent stratus overcast. 



The character of the sound-velocity structure can 

 be seen by examining the vertical velocity distribu- 

 tions computed from the data obtained by bottle 



