Paper 6 



these five locations. Upwelling indices at 54N/ 134W and 51n^ 

 131W for May and July were the lowest (Largest negative values) 

 calculated in the 31-yr time series. Coastal convergence 

 continued through the summer at approximately one-half the 

 intensity of the preceding winter's downwelling. Under these 

 conditions/^ the existing baroclinic structure would tend to be 

 maintained. This situation contrasts with more typical relaxed 

 summer conditions^ in which the ba roc I i ni c i t y established during 

 a previous winter is dissipated. 



A smooth transition to vigorous winter downwelling was replaced 

 by less inteose than normal downwelling in October. This period 

 of positive anomalies immediately followed and preceded several 

 months of large negative anomalies. An examination of the 

 monthly mean surface atmospheric pressure field for October (not 

 shown) indicated a westward shiftx relative to the long-term mean 

 position^ of the center of the low pressure system and a much 

 reduced pressure gradient near the coast. A return to near 

 normal (50th percentile) winter downwelling occurred in December. 



VANCOUVER ISLAND TO POINT CONCEPTION 



The stretch of coast from Vancouver Island (48N) to Point 

 Conception (36N) is a transition zoner in which wind driven 

 surface transport changes from predominantly onshore to 

 predominantly offshore. Durino 1976 this entire coastal region 

 was characterized by a pattern of three periods of more positive 

 than normal upwelling indices separated by two short intervals of 

 more negative than normal indices. These features repeat the 

 general pattern noted in the previous section^ and indicate a 

 degree of coherence in the large scale atmospheric circulation on 

 space scales approaching 1^200 km and on time scales of two to 

 four months . 



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67 



