576 EIGHTH PACIFIC SCIENCE CONGRESS 



northern or southern flow as the point of division of the major current 

 shifts south or north. 



Previous studies in the northeast Pacific Ocean have examined 

 small parts of the system. The U.S.S. Bushnell (Sverdrup et ah, 1942) 

 crossed the Sub-Arctic Current from the Aleutians to Hawaii. U.S.S. 

 Oglala (Goodman and Thompson, 1940) crossed from the Aleutians 

 to Juan de Fuca Strait. The International Salmon Commission (Mc- 

 Ewen et ah, 1930) examined three sections normal to the coast in the 

 Gulf of Alaska. Each of these studies shows part of the general picture. 

 When they are considered together it is evident that there is a con- 

 tinuous circulation of low salinity coastal water, in a counterclockwise 

 direction all around the Gulf. Part of this stream is dissipated through 

 the Aleutian Islands into the Bering Sea and the remainder moves 

 southwards to join the continent-bound Sub-Arctic Current. The low 

 salinity surface zone water found throughout the Gulf of Alaska is pro- 

 bably due to the conservation and re-circulation of a substantial part 

 of the coastal water, as well as to the high precipitation associated with 

 the semi-permanent Aleutian low pressure area. 



Thompson and Van Cleve (1936) have deduced from drift bottle 

 experiments that in March 1932 the division of the Sub-Arctic Current 

 to form the Alaska Gyral and the California Current occurred well 

 south of Latitude 47 °N. They point out that this conforms to the la- 

 titude of the division between residual winds, with a northerly and 

 southerly component, as calculated from the Pilot Charts. The result- 

 ing current along the British Columbia coast in the winter agrees well 

 with this. 



From drift bottle experiments during the summer of 1931, Thomp- 

 son and Van Cleve concluded that the division of the currents occurred 

 further north at Latitude 50° N, which again agrees well with the divi- 

 sion of winds deduced from the Pilot Charts. This conclusion is also 

 supported by Tully's (1938) examination of the waters within 100 miles 

 of Vancouver Island in 1936. These indicated that the general flow was 

 southeasterly and suggest that the division of the great current was 

 north of Latitude 50 °N in that summer. These early observations ap- 

 pear to contradict the findings of the 1950 and 1951 studies where the 

 general movement appears to be northward. However, when these are 

 viewed as part of the overall picture (Figure 8) it is evident that there 

 is no contradiction. The southward movement occurs near the coast of 

 Vancouver Island, while the northward tendency is further offshore, 

 and becomes stronger to northward. 



These earlier studies are not complete enough to describe the 

 character and location of the great divergence with any precision, and 



