PHYSICAL OCEANOGRAPHY OF THE GULF OF MAINE 



607 



TEMPERATURE AT 40 METERS 



The regional differences that developed in the vertical distribution of tempera- 

 ture between various parts of the Gulf of Maine, as the summer advances, tend to 

 make the temperature (as plotted in the horizontal projection) more nearly uniform 

 in the mid depths than it is at the surface. Thus, all the 40-meter readings for the 

 month of August of the y^ars 1912 to 1915 (figs. 52 to 54), and 1922 (omitting for 

 the moment the cold summers of 1916 and 1923), have fallen within a range of 6°, 

 from a maxunum of 11.5° off Lurcher Shoal (station 10031, 1912) to a minimum of 

 5.5° off Cape Sable (station 10243, 1914). Only 6 August readings at 40 meters, 

 out of a total of 64, have been as warm as 10° to 11°; only 3 cooler than 6°, and 



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I ' '^ 1 



Fig. 52.— Temperature at a depth of 40 meters, August 5 to 20, 2913 



the great majority have fallen between 7° and 9.5°, irrespective of precise geo- 

 graphic location. Consequently, this may be taken as the normal temperature to 

 which the 40-meter stratum of the gulf as a whole warms by the end of the summer. 



With so narrow a range, and with the water continuing to warm until well into 

 the autumn, a difference in date of a few days one way or the other will be accom- 

 panied by a greater difference in temperature, at this level, than any regional differ- 

 ence that might be disclosed by a simultaneous survey of the whole western and 

 northern part of the gulf. 



Differences between cold and warm years, illustrated by a temperature of about 

 8° on August 9, 1913 (station 10088), but only 5.75° at the same locality in 1914 on 

 the 22d of that month (station 10254), likewise outweigh the regional differences for 



