PHYSICAL OCEANOGRAPHY OF THE GULF OF MAINE 



645 



A thermal distribution of the opposite sort, with a shelf of cold water projecting 

 seaward, has been recorded repeatedly off this part of the slope at the end of the 



summer. 



NOVEMBER AND DECEMBER 



In 1912 the whole column of water oflF Gloucester had become vertically homo- 

 geneous in temperature (about 9°) by November 20 (fig. 75) , suggesting that autum- 

 nal cooling had proceeded at about the same rate there as it did in 1915 and 1916 

 (p. 638), while the whole column, 70 meters deep, had cooled to about 7.8° to 8.1° by 

 December 4 (station 10048). It is interesting that the immediate surface was 0.1° 

 to 0.3° warmer there than the deeper levels on both these dates, which may have 

 reflected irregularities and setbacks in the progress of coohng from day to day, 

 because both these stations were occupied after one or two warm days, though on 



METER 



220 



Fig. 74.— Temperature profile crossing the continental shelf off Narragansett Bay, November 10 and 11, 1916 (stations 10405 



to 10508) 



both occasions the air temperature was a degree or so colder than the water at the 

 times the readings were taken. 



The Fish Hawk again found the temperature virtually uniform vertically, from 

 surface to bottom, aU along the southern side of Massachusetts Bay on Decmber 

 3, 1925, in depths of 25 to 40 meters; in fact, the surface reading did not differ by more 

 than 0.2° from the interm.ediate or bottom reading at any of the 10 stations. The 

 progress of autumnal cooling also was made evident by a mean temperature of about 

 6.2° for this side of the bay. Although the preceding autumn had been unusually 

 mild (suggesting that in most years the sea temperature is a degree or two lower 

 by that date), one station off Plymouth Harbor (No. 10) and two at the head of the 

 37755—27 10 



