PHYSICAL OCEANOGBAPHY OF THE GULF OF MAINE 



629 



of the gulf in July. But even allowing for this factor, a considerable annual differ- 

 ence in surface temperature remains to be accounted for between the cold July of 

 1916 and the warmer years, 1913 to 1915. 



Furthermore, the vertical warming below 100 meters, so characteristic of this 

 side of the gulf in 1914 and 1915 (Bigelow, 1917), was hardly appreciable in 1916. 

 During the interval, July 22 to August 29, the mid layers off northern Cape Cod 

 warmed by about 1° or 2° (stations 10344 and 10398). Even then, however, the 

 temperature did not equal that of 1912 on the same date (station 10043, August 29), 

 or of 1913 three weeks earlier (station 10086, August 5; Bigelow, 1922, p. 91). 



The surface water on the northwestern part of Georges Bank was also about 2° 

 colder in July, 1916, than in that month of 1913 or of 1914, as appears from the 

 following table: 



The difference in temperature between July of 1916, on the one hand, and of 

 1913 and 1914, on the other, was even wider along the southern edge of the bank. 

 Violent annual, even day by day, fluctuations are to be expected there (Bigelow, 

 1922, p. 10), but nothing in our previous experience foreshadowed summer tempera- 

 tures as low as those of 1916, when the bottom water was 4° colder there than in 

 1914, though the stations for the two years were close together in location and the 

 surface temperatures (17° to 18°) were almost alike. The surface near the continen- 

 tal edge south of Nantucket lightship and the depths greater than 50 meters were 

 likewise 3° to 4° colder in July, 1916 (station 10351), than in that month in 1913 

 (station 10061) ; and the cold band just outside the edge was 4° to 5° (fig. 67) instead 

 of 9° to 10°, as we had found it in 1914 (fig. 58) . 



There is nothing unprecedented in a vertical distribution of temperature of the 

 type shown on this 1916 profile (fig. 67) over this part of the slope; indeed, its repeated 

 occurrence suggests that something of the sort is to be expected except when obscured 

 by encroachments from the warm water of the so-called "Gulf Stream" (p. 608). 

 The surprising feature of the summer of 1916 is that the temperature of the coldest 

 layer should have been so low and that water so cold lay so close to the surface of the 

 open sea in July at this latitude. In fact, as I have elsewhere noted (Bigelow, 

 1922, p. 103), this July temperature very closely paralleled the temperature taken 

 at the same relative position on the slope off Cape Sable, about 200 miles to the north- 

 eastward, on June 24 of the year previous (station 10295). 



The Grampus did not visit the eastern side of the gulf in the summer of 1916, 

 where the water was also unusually cold during that summer, as Dr. A. G. Huntsman 

 writes:^' 



" Quoted from a letter from Doctor Huntsman. 



