556 



BULLETISr OF THE BI'EEAU OF FISHERIES 



spring than tliis event is usually to be expected allowed a decided warming of the 

 upper stratum to 2.8° to 3.5° from the Cape Sable slope out to Browns Bank, though 

 with very little change from March to April on the Georges Bank side. 



MAY 



SURFACE 



From late April, on, the temperature of the western side of the gulf constantly 

 rises, most rapidly at the surface, progressively slower with increasing depth. Near 

 Cape Sable, in the eastern side, however, the vernal cycle is dependent on the vol- 

 ume, temperature, and seasonal "time table" of the Nova Scotia current. Where 



_jjffZ £54! =?/^°_ _ ^-*2'' J^l £^1. 



J42' 



J.^/'' 



-J££°^ 



.dl/L 







20 

 40 

 60 

 80 



too 



120 

 140 

 160 

 180 

 200 

 220 

 240 



260 



Fig. 26. — Temperature profile running from the eastern part of Georges Bank, across the Eastern Channel, Brown's Bank, 

 and the Northern Channel, for April 15 and 16, 1920 



this debouches into the gulf the surface stratum is at its coldest some time in April 

 or even as early as the last of March in "early" years (1919, for instance), but not 

 until May in "late" years, as probably happened in 1920. Unfortunately, neither of 

 our May cruises (1915, 1920, or 1925), nor the ice patrols stations for 1919, has covered 

 the gulf as a whole ; hence I can offer only a composite picture for the month, based on 

 years that certainly differed considerably in the rate of vernal warming and in the 

 date at which the chilling effect of the Nova Scotian current reached its maximum. 

 On this basis the highest surface temperatures of earty May (fig. 27) are to be 

 expected in Massachusetts Bay, the lowest in the Cape Sable-German Bank region, 

 with the whole area west of the longitude of Penobscot Bay warmer than 6° by the 

 10th, if not earlier, contrasted with surface readings of about 3° or lower off western 

 Nova Scotia." 



"Three degrees on German Bank, May 9, 1915 (station 10271); 2.7° there on Apr. 28, 1910 (ice patrol station No. 22). 



