Oceanic Circulation and Temperature 

 annual normal range. Again, the maximum and 

 minimum temperatures occur in-shore some months 

 after the corresponding normal times; and the 

 variation of the in-shore temperatures with respect 

 to the latitude is scarcely half the normal amount. 



SUBFACE TeMPESATUBES AT LaTITCDB 



OF Sak Diego 



)', 150 Miles South 



Average ocean 

 temperatures for 

 the whole circle 

 having the given 

 latitude 



Temperature ot the 

 Pacific at the 

 boimdary of the 

 California and 

 Japan currents 



Temperature of the 



In-shore water 



along the Pacific 



Coast 



Temp. 



Time of oc 

 currence 



Temp. 



Time of oc- 

 currence 



Time of oc- 

 currence 



Ml ntmum ,,, 



Annual range- 



August 

 February 



Aug., Sept 

 AprU 



September 

 May 



Surface Temperatures at Latitude 40°, Off Cape 

 . Mendocino 



Summary of Hypotheses Proposed to Account 

 FOR THE Belt of Cold In-shore Water Along the 

 West Coast of North America. — In the earlier ex- 

 planations of the temperature anomalies then 

 known, the assumption of a southerly surface drift 

 from the Arctic was prominent. As later observa- 

 tions indicated belts of alternately warm and cold 

 water lying at right angles to the coast, and re- 

 vealed the presence in the summer time of the 

 coldest in-shore water at latitude 40°, this hypothe- 

 sis was abandoned in favor of the view that off- 

 shore winds caused an upwelling of bottom water 

 all along the coast, as had been demonstrated by 

 Murray in the case of certain shallow lakes. But 

 more careful attention showed that this would re- 

 quire an extension of the trade wind belt greatly 

 beyond its observed limit, the prevailing winds be- 

 ing mostly in-shore where the cooling effect is 

 greatest. By assuming that an eastward drift, ex- 

 tending from the bottom to the surface, prevailed 

 over a wide belt of the northern portion of the 

 Pacific, Holway in 1905 accounted for several of 

 the facts without incurring the objection that ap- 

 plied to the former hypothesis. However, the new 

 and more detailed facts revealed by later observa- 

 tions made it plain that the above explanations 

 were inadequate. 



Recent Researches on the Oceanic Circula- 

 tion AND Temperature Distrirution Off the Pa- 

 cific Coast. — By attempting to explain and inter- 



135 



