oj the Surface Water of the Atlantic and Pacific. 69 



Atlantic Waters, Canadian Fisheries Expedition, under the Direction 

 of Dr. Johan Hjort, 1914-1915. Sandstrom applies the Bjerknes 

 theory of circulation to the waters of the Newfoundland region, which 

 shows that Archimedean forces have more to do with the formation 

 of ocean currents than has the wind. Thus, the Gulf Stream flows 

 from the tropics toward Spitzbergen because the light surface layer 

 of the ocean, which is heated by the sun, is 600 meters deep in the 

 tropics and only 200 meters deep at Spitzbergen; hence the thicker, 

 deeper part of this wedge of light water must constantly flow toward 

 its thin edge at Spitzbergen in a futile attempt to overcome this 

 difference in thickness and reduce the whole wedge to a horizontal 

 surface layer of uniform thickness. Of course, if this were ever 

 accomplished, the current would stop after a few oscillations, but 

 the unequal heating ability of the sun in the tropics and in the 

 Arctic regions keeps the current moving. 



We can not dwell upon this interesting subject, nor is it necessary 

 so to do, for it could hardly be more clearly and simply explained than 

 by Dr. Sandstrom. Suffice it to say that the prevailing Avesterly 

 drift of the hot, light surface waters in the tropics must produce an 

 easterly current in a heavier and colder layer of water which lies 

 beneath the surface. At or near the heat equator, however, we would 

 expect that this deep layer would at times be brought to the surface 

 by the upwelling known to exist in this region. This would, however, 

 not interfere with its horizontal movement until it reached the 

 surface and moved against the prevailing wind. As is well known, 

 the rotation of the earth about its axis gives to ocean currents in the 

 northern hemisphere a tendency to swerve toward the right. On the 

 equator, however, there is no such tendency, but it increases as the 

 sine of the latitude, although in a latitude so low as 5° N. it would be 

 practically negligible. Hence, in this region, if the surface current 

 moves toward the west the deep layer would move toward the east, 

 and there would be but little tendency for it to diverge toward the 

 southeast and south. This tendency to swerve toward the right is of 

 course not wholly lacking even in low latitudes in the northern 

 hemisphere, and thus the great westerly drift of the surface water 

 of the tropical Pacific eventually turns northwestward and finally 

 northward, and flows along the coasts of China and Japan as the 

 "Japan Current." 



If the easterly surface current which is sometimes met with in 

 about 5° north latitude in the mid-Pacific consists of deep water 

 which has been brought to the surface by upwelling, it might, for a 

 time at least, retain some of the characteristics of the deep water of 

 the ocean, even after it reaches the surface. 



Thus we may readily account for the slightly lower temperature 

 of the water of these easterly currents as compared with that of the 



