



■#^r 









10 *^S% 





&• — 





9 T 







6* 



^•j 



225 J70 315 



-^ 



Figure 12. — Relative frequency surfaces and frequency histograms for January. Data are shown for the 1 -degree squares labelled 6 through 10 in 

 the upper left inset. Contours of relative frequency are drawn at intervals of 2.5%. Mean vector wind stress is indicated by an arrow. 



of wind stress are evident near Punta Eugenia in May. A 

 large maximum occurs just south of Cape Mendocino 

 between May and August. A smaller, local maximum oc- 

 curs in May and June at lat. 36°N. 



Figure 13 is similar in appearance to a time series of 

 offshore Ekman transport shown by Bakun et al. (1974). 

 They showed a good correlation between the occurrence 

 of maximum offshore transport at lat. 39°N and a sup- 

 pression of seasonal warming in the adjacent coastal 

 waters during early summer, which is indicative of up- 

 welling. The timing of the central wind stress maximum 

 off the coast from Cape Mendocino agrees with the 

 description of the mean yearly cycle of indicated up- 



welling given by Bakun (1973). However, Bakun's data 

 are spatially distorted, and indicate maximum values at 

 lat. 33°N, long. 119°W in the middle of the Southern 

 California Bight. The spatial distortion is primarily 

 caused by development of an intense thermal low over 

 southern California during the summer. The influence of 

 this low pressure system, and the effects of coastal moun- 

 tain ranges distort the analyzed pressure fields used in 

 Bakun's computations. 



The time series of alongshore surface wind stress (Fig. 

 13) suggests a slight tilt, with time and space, to the 

 region of maximum values. This corresponds to a north- 

 ward shift in the intensity of the surface wind stress from 



18 



