PHYSICAL OCEANOGRAPHY OP THE GULF OF MAINE 



565 



showing a warming of about 4° at the surface (7.22° to 8.33° in May, according to 

 the locality), but with very little change at 100 meters. 



Turning now to the opposite side of the gulf, Mavor's (1923) tables show the cen- 

 tral part of the Bay of Fundy warming only fractionally at any level from April 9 

 to May 4, 1917 (whole column then between 1.9° and 2.8°), bub then more rapidly 

 to 8.18° at the surface, 4.68° at 30 meters, and 3.92° at 100 meters on June 15. 



Assuming, from the character of the winters preceding, that the mean temperature 

 at 40 meters ranged about 1° lower at the beginning of spring in 1920 than in 1915, 

 the difference between the April and May readings, just summarized, suggests that 



Temperature, Centigrade 



1° 2° 3° 4° 5° 6° 7° 8° 

 Meter 



10 



20 



30 

 40 

 50 

 60 

 70 

 80 

 90 



Fig. 33.— Vertical distribution of temperature in Ipswich Bay on April 9, 1920 (A, station 

 20092), and on May 7 and 8, 1920 (B, station 20122) 



this level normally warms by about 1° during the interval from mid-April to[mid-May 

 in the parts of the gulf where the change is most rapid. 



Taking the open gulf as a whole, the 100-meter readings for April, 1920 (a cold 

 year), so closely reproduced the May readings for 1915 (a warmyear)^^ that the tem- 

 perature of the mid-depths may be described as virtually stationary during this part 

 of the spring. 



As the result of the two contrasting processes — vernal warming in the western side 

 of the gulf and the inflow of cold water into the eastern — the regional distribution 



"Maximum divergence at this level, for pairs of stations, was only from 3° in the western basin on Apr. 18, 1920, station 

 20115, to 4.8° on May 4, 1915, station 10267. 



