586 EIGHTH PACIFIC SCIENCE CONGRESS 



tildes. Off the Washington and Oregon Coasts in winter, the Davidson 

 Current feeds water northward inshore. The area studied, being an 

 area of divergence, is characterized by weak and poorly defined currents 

 which are easily influenced by temporally changing wind patterns and 

 local bathymetric irregularities. 



The measurements to be reported in this paper were carried out 

 with the research vessel M. V. BROWN BEAR during seven offshore 

 cruises in the spring and summer months of 1952 and 1953. Because 

 of the anticipated variations of currents with time, determinations of 

 circulation patterns by dynamic topographies were supplemented by use 

 of the Geoniagnetic-Electro-Kinetograph (G.E.K.). It was quickly dis- 

 covered that the latter instrument was measuring cunents (or effects) 

 very much greater than those from dynamic topographies, and showing 

 a rotary variation with time. In recent cruises therefore, several time 

 studies have been made to discover the nature of the rotary variations. 



Further evidence of the reality of the rotary variations was ob- 

 tained by direct current measurements from an anchor station on Cobb 

 Seamount, a seamount rising very sharply from 1500 fathoms depth to 

 within 16 fathoms of the surface, and located approximately 270 miles 

 west of the Washington Coast (46°-45.5'N, 130°-46.3'W). The results 

 from two such time studies are presented in some detail. 



Another sphere of activity has been a detailed investigation of the 

 outflows of the Strait of Juan de Fuca and the Columbia River, par- 

 ticularly the latter. The outflow of the Columbia has been traced for 

 over 200 miles seaward. The position and structure of this long plume 

 of less saline water is of interest as an indicator of offshore circulation 

 and mixing, and because of the possible influence it may exert in di- 

 recting the salmon which migrate to and from the river. 



The circulation near the coast of Vancouver Island and the mouth 

 of the Strait of Juan de Fuca has been discussed by Tully (1938, 1941) 

 on the basis of salinities and temperatures measured near the coast, 

 often in shallow water. These measurements as well as those of Mar- 

 nier (1926) made from Swiftsure Lightship establish the direction of 

 outflow of the Strait of Juan de Fuca as northwestward, very close and 

 parallel to the coast of Vancouver Island. Tully further shows the 

 accumulation of fresh water along the coast due to the prevailing south- 

 westerly winds in spring and early summer, with a gradual transition 

 to a condition of upwelling in a narrow band along the coast under 

 influence of the northerly winds of late summer. He interprets the 

 resulting dynamic topographies as representing northwesterly flows close 

 to the coast in early summer and a reversal in direction in late summer. 

 I'he latter flow, however, is overcome by the generally northwesterly 



