PHYSICAL OCEANOGRAPHY OF THE GXJLE OP MAINE 687 



The mean annual temperature of the surface of the gulf affords evidence to the 

 same effect, this being about the same at the mouth of Massachusetts Bay (9 to 

 10°) as the annual mean for the air at neighboring localities around its shore, 

 or slightly warmer. A similar relationship has been recorded between the mean 

 annual temperature of the surface water of the Bay of Fundy'^ and of the air over 

 the neighboring parts of New Brunswick and of Nova Scotia. 



Most instructive clues to the temperatures that might be expected to prevail in 

 the deep strata of the Gulf of Maine if its basin were so nearly inclosed that it could 

 not be affected appreciably by currents from outside are to be found in the relation- 

 ships between its deep temperatures and those of the Norwegian fjords (Nordgaard, 

 1903) and of the Black Sea. 



In the southwestern Norwegian fjords, where a very heavy rainfall maintains so 

 high a stability that convection al overturnings are confined to the superficial stratum, 

 so that this alone is directly exposed to winter chilling, the bottom temperature is 

 not only uniform throughout the year but is almost precisely the same as the mean 

 annual temperature of the air."* So close, in fact, is the correspondence that, 

 Nordgaard tells us, one need only take a reading of the bottom temperature in one 

 of the deep southern fjords to know the mean annual temperature of the air. In 

 the northern fjords, however, which receive so much less rain that the water is less 

 stable, salinity and temperature become nearly equalized from surface to bottom by 

 convectional circulation in winter, just as they do around the coastal belt of the 

 Gulf of Maine, and as a result of this winter chilling causes wide seasonal variations 

 and winter temperatures lower than the mean annual temperature of the air at 200 

 meters and deeper. In both these classes of fjords, as Nordgaard (1903, p. 46) 

 points out, the bottom temperature is purely the result of local factors, the topog- 

 raphy of the bottom being such that "no supply of heat by a submarine current is 

 possible," nor any supply of cold of similiar origin. 



More pertinent to the Gulf of Maine is the relationship between the air and 

 water temperatures of the Black -Sea, situated at about the same latitude (most of 

 its area is included between the parallels of 41° and 45°), but in a somewhat warmer 

 cHmatic zone."^ 



At depths greater than 150 to 200 meters the entire area of the Black Sea is 8.8° 

 to 9° the year round (Spindler and Wrangell, 1899; Skvortzov and Nikitin, 1924), con- 

 trasting with mean air temperatures for the year of about 9.6° at Odessa, on the 

 north shore, about 11° over the western (Bulgarian) watershed, and about 14.3° at 

 Batum on the eastern coast. That the deeps of the Black Sea should be so much 

 colder than the mean annual temperature of the overlying air, in spite of the warming 

 effect of the bottom current flowing in from the Mediterranean, reflects the age-long 

 effects of winter chilling from above. Obviously the differential can not be credited 

 to any Arctic current in this case. 



While no part of the Gulf of Maine is as thoroughly protected from thermal in- 

 fluences from the sea outside as are the Norwegian fjords and the Black Sea, such 



83 Between 6° and 7° for the year 1916-17, according to Mayor's (1923) tables. 



" Nordgaard (1903) quotes 7° as the mean annual temperature of the air at Bergen, 6.8° to 7° at 400 meters and deeper in the 

 neighboring fjords. 



•» The Black Sea is usually represented on climatic charts as occupying the belt inclosed between the mean annual isotherms 

 for 10° and 15.66°. 



