Ocean Temperatures along the West Coast of North America. 261 



coldest surface water was in the vicinity of Cape Mendocino, lat. 40, 

 is fully verified by the maps in Thorade's (14) article. And from the 

 present theory we would expect the water there to be colder than that 

 farther south because of the higher latitude and the upwelling combi- 

 ned. North of this region the wind component parallel to the coast 

 is directed to the south but rapidly diminishes, being only 2 or 3 miles 

 per hour off Vancouver, less than 500 miles farther north, while the 

 velocity at latitude 40 is about 15 miles per hour. So we would 

 expect the quantity of cold water upwelling to diminish proportiona- 

 tely in that distance. The normal temperature for the latitude of 

 Vancouver is about 2 more than the actual temperature off Cape 

 Mendocino from June to September, but is about 2 less during the 

 rest of the year. The charts show as would be expected that off 

 Vancouver the temperature is practically independent of the distance 

 from the coast. 



The presence of abnormally cold water on the continental shelf, 

 referred to in Hoi way's article, would result directly from Ekman's 

 theory, as the prevailing wind direction is such as to drive the bottom 

 water toward the coast over this slope. 



Along the west coasts of Africa and South America the prevailing 

 wind directions (15) are such that a temperature distribution similar to 

 that off the west coast of North America would be expected on the 

 basis of Ekman's theory, remembering that in the southern hemisphere 

 the deflecting force is directed to the left of the motion. This agrees 

 with the observations which indicate a reduction of in- shore tempera- 

 tures corresponding to the strength of the wind component parallel to 

 the coasts. 



The qualitative agreement being so satisfactory, it seemed very 

 desirable* that a detailed and quantitative test should be made. And 

 I have attempted to so formulate the problem of the distribution of 

 ocean temperatures along the west coast of North America that it could 

 be put into mathematical language and solved with the aid of Ek- 

 man's equations of fluid motions. 



V. The mathematical formulation of the temperature problem for a 



given locality. 



Assumptions. The normal in- shore temperature for any latitude 

 is the same as the actual temperature at a point in mid-ocean having 

 the same latitude. 



