588 EIGHTH PACIFIC SCIENCE CONGRESS 



Water Properties and Circulation 



As others have suggested, the horizontal gradients of temperature 

 and salinity may be generalized in two representations, one for spring 

 and early summer and one for late summer. The winter conditions 

 have not been studied. Figures 2 and 3 show the horizontal distribu- 

 tion of surface temperature and surface salinity in April-May, 1953, the 

 data having been smoothed to eliminate local fluctuations. The piling 

 up of warm surface water along the coast of Vancouver Island is evident. 



Figures 4 and 5 show the conditions in July 1952. Here the break- 

 down of spring conditions is just beginning to appear. The water 

 which earlier increased in temperature essentially up to the coast is now 

 showing a wide band of somewhat cooler water near the coast. The 

 effect is more marked if vertical sections of temperature are plotted, 

 demonstrating the decrease in thickness of the surface water layer on 

 approaching the coast. Close to the mouth of the Strait of Juan de 

 Fuca, the effect is accentuated at the surface probably because of the 

 mixing processes of tidal flow as well as the tendency of upwelling 

 deeper water to appear far within the Strait. 



Figures 6 and 7 (smoothed somewhat) show the conditions in Sep- 

 tember 1953, farther south. Although not completely comparable with 

 the above data because of the different areas covered, there is still sur- 

 ficial evidence of upwelling in the region near the mouth of the Strait 

 of Juan de Fuca. Along the Washington Coast south of the Strait, the 

 subsurface temperature structure indicates the presence of upwelling 

 which, however, does not reach the surface because of a blanketing layer 

 of less saline water. This is especially so in the vicinity of the Colum- 

 bia River mouth where the surface waters flowing seaward are rapidly 

 replaced by river effluent. Along the Oregon Coast south of the Colum- 

 bia, low temperatures characteristic of upwelling are again apparent at 

 the surface. 



Figures 6 and 7 also show the first results of a detailed study of 

 the Columbia River outflow. The plume of water having a salinity 

 less than 32.0o/oo is seen to extend over 200 miles to the southwest. 

 Associated with the lower salinity is a somewhat higher temperature. 

 The position of the wake stream is in itself evidence of the generally 

 southerly set of the currents in this region during the summer. At the 

 velocities indicated by the dynamic topography for the general area, 

 the time required for the water to travel to the outer limits of the 32°/oo 

 isosal is of the order of one to two months, and hence the position of 

 this limit establishes a minimum value for the integrated currents for 

 at least this period. 



