69 



conditions: (1) the water is uniformly stratified with respect 

 to salinity, (2) the horizontal temperature gradient becomes 

 zero at the bottom, (3) the topography of an isothermal layer 

 is not distorted by other factors, and (4) the effect of 

 friction is negligible. The first condition is approximately 

 fulfilled in Santa Monica Bay. The second is not, for from 

 the great number of temperature measurements taken over the 

 San Pedro and Santa Monica shelves, it is quite apparent that 

 no such level surfaces exist in these waters. The third con- 

 dition also is not fulfilled, although its relative importance 

 is difficult to assess, as is the effect of friction. 



In spite of these limitations, it can be demonstrated that 

 there is a general correspondence between the current directions 

 as deduced from temperature distribution and those obtained 

 from empirical measurements. 



The paths of the surface and subsurface drogues used in 

 May, June, and July 1956, and the corresponding temperature 

 surfaces are shown in Figures 23, 24, 25, 26, and 27. The 

 paths of the drogues in the surface layers followed closely 

 the thermal gradients. However, the subsurface drogues were 

 not as closely aligned with the isothermal lines as one might 

 have suspected. It is believed that three possible uncon- 

 trollable situations may have resulted in the non-conformity. 

 First, since the contours were drawn free-hand with no attempt 

 to correct the bathythermograph traces, a slight variation 

 or correction could easily superimpose the contours and the 

 drogue path. Second, the positions of the bathythermograph 

 casts were taken while the ship was underway, so that a 



