OCEANIC CIRCULATION AND 



TEMPERATURE OFF THE 



PACIFIC COAST 



BY GEORGE F. MCEWEN 



Scripps Institution for Biological Besearch, 

 La Jolla, California 



DEPTH OF THE PACIFIC. — ^The Pacific Ocean oc- 

 cupies a basin extending over an area of 

 69,000,000 square miles, and has a depth aver- 

 aging from 2000 to 3000 fathoms. While the Ant- 

 arctic Ocean is an integral part of the Pacific Ocean, 

 communication with the Arctic Ocean is limited to 

 the relatively small channel of Bering Straits. The 

 eastern portion of the Pacific is characterized by 

 great uniformity of depth, mostly exceeding 2000 

 fathoms, with a few volcanic islands and a number 

 of deep submarine valleys extending nearly to the 

 shore line. The western*^ portion, with its irregular 

 depth-contours and numerous high volcanic ridges 

 and islands, is in complete contrast with the eastern 

 portion. 



Ocean Currents of the North Pacific and 

 Their Climatic Influence. — The warm Kuro Siwo, 

 or Japan Current, which is similar in many respects 

 to the Gulf Stream of the Atlantic, flows north from 

 the equator along the Asiatic coast. From there 

 it turns east and strikes the North American coast 

 at Sitka, Alaska, with a considerably diminished 

 velocity and volume. From this point it broadens 

 out and drifts slowly toward the equator, curving 

 away from the coast. While this current has long 

 been popularly supposed to exert a powerful in- 

 fluence on the California climate, authorities now 

 agree that this is erroneous. 



The southward drift of surface water border- 

 ing the Pacific Coast between latitudes 40* and 20* 

 is known as the California Current. This current, 

 which is distinguished by its low temperature from 

 what would naturally be called the eastern portion 

 of the Japan Stream, flows southward as a cold 

 current, increasing in volume and breadth until 

 at latitude 25° it extends more than 1000 miles 

 off-shore. Indeed it really is the part of the Japan 

 Stream bordering the Pacific Coast, and doubtless 

 would not have been given a different name were 

 it not for its low temperature and relatively greater 

 velocity. While the existence of this current, the 



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