PHYSICAL OCEANOGRAPHY OP THE GULP OP MAINE 



685 



As every coastwise navigator knows, there is much less fog along the western 

 shore of the gulf from Cape Cod to Cape Elizabeth than there is at the mouth of the 

 Bay of Fundy. Consequently, the former is exposed to more hours of direct 

 sunlight, tending to accentuate the difference in temperature resulting from differ- 

 ences in latidude, per se. On the other hand, winds from the quadrant between west 

 and south, such as prevail over the Gulf of Maine during July and August (p. 965), 

 tend to drive the warmed surface water eastward toward Nova Scotia, thus trans- 

 ferring heat from southwest to northeast (with more or less colder water welling up 

 along the western shore) , and so in part to counteract the difference in the rate of 

 solar warming which would otherwise accompany the difference of latitude. With 

 a "run" of easterly winds the direction of surface drift will be reversed. Thus, it is 

 by no means a simple task to account for variations in the mean temperature as 

 narrow as those prevailing between different parts of the Gulf of Maine in the 

 summer months. The much wider regional variations in surface temperature or in 

 the temperature of the water at any given level below the surface follow much 

 more obvious causes. 



I think it sufficiently estabUshed, however, that the difference between the mean 

 temperature of the column of water (in other words, its potential temperature) in 

 the northeastern part of the gulf and in the southwestern part is not greater in most 

 summers than can be accounted for by the difference of latitude and by such other 

 local causes as fog, the direction of the wind, and the regional difference in the ac- 

 tivity of the vetical tidal mixing, on which too much stress can hardly be laid. 



This is still more certainly the case in winter, when the temperature of the gulf 

 is so nearly uniform, vertically, that station for station comparison of the actual 

 readings at once reveals any regional differences in the mean temperature. 



In winter it is only close along shore that any unmistakable difference between 

 the northeastern and southwestern parts of the gulf can be demonstrated, and this 

 is not wider than can be accounted for by the difference in latitude. 



Winter temperatures at representative stations during the cold months, ° C. 



The foregoing discussion leads to the conclusion that the cold water from the 

 Nova Scotian current is soon so thoroughly incorporated with the water of the gulf, 

 after the flow past Cape Sable slackens, that in most years the regional disturbance 

 of temperature which it causes at first is entirely dissipated by June. Even in years 

 when the longshore drift continues to pass Cape Sable until late in the summer 

 (p. 834) , it may, at the most, hold the mean temperature a degree or two lower along 

 western Nova Scotia until July than it is out in the neighboring basin of the gulf. 

 After that (earlier still in "early" seasons) the surface water contributed by this 



