51- N 



Figure 18. — Temperature ("C), at 200 m., fall 1963. (The 183- and 1,829-m. depth contours are 

 shown.) 



tions, Nansen bottles were tripped 5 m. from 

 the bottom by two methods. In the first 

 method, the Nansen bottle is placed 5 m. above 

 a weight suspended on the end of the wire, 

 and the bottle is tripped by a messenger when 

 a change in wire tension indicates the weight 

 is striking the bottom. In the second method, 

 a Nansen bottle attached to a tripping mechan- 

 ism is reversed when a weight suspended 5 m. 

 below the device strikes the bottom. Although 

 agreement of results from both methods was 

 good, values obtained by the first method were 

 used for most stations. Because of the limited 

 depth range of the vessel's echo sounder (about 

 550 m.) and the inability to detect the bottom 

 by wire tension at great depths, the locations 

 of the 914-m. and 1,829-m. stations were de- 



termined from charted depths ; thus, the in- 

 terval between the deepest bottle and the bot- 

 tom depended upon the accuracy of the charted 

 soundings and the vessel's position. 



The spring values of salinity and tempera- 

 ture near the bottom varied most at shallow 

 depths along the Continental Shelf and were 

 uniform along the Continental Slope (fig. 21). 

 At 55 m. salinity values were uniform between 

 '31.9%o and 32.0%o north of the Strait of 

 Juan de Fuca, but increased off Washington. 

 The maximum of 33.4%o was near the mouth 

 of the Columbia River. The range of tempera- 

 ture values at 55 m. was about 1.0° C. The 

 minimum value occurred off the Columbia 

 River. The maximum salinity and minimum 

 temperature indicated that water which is 



GEOSTROPHIC CIRCULATION 



241 



