108 



temperature is about 33° F. at the start of the season and 50° F. at 

 its close, a rise of 17° F. Along the eastern edge of the Banks the 

 true cold water rises from about 32° F. to about 47° F., a rise of 15° F. 

 Between the forty-seventh and forty-eighth parallels the Labrador 

 Current surface water during the same time warms from about 

 32° F. to about 44° F., a rise of 12° F. South of the Banks along the 

 fortieth parallel in the Gulf Stream the rise during a 100-day ice-patrol 

 season amounts to 10° F., from about 60° to 70° F. 



The varying rates of warming in different areas about the Grand 

 Banks are in the main easilj" accounted for. The Grand Banks water, 

 for instance, is shoal and it is somewhat less subject to fog blankets 

 than the Labrador Current. Moreover it is relatively stationary 

 in so far as the effects of true ocean currents, as distinct from tidal 

 ones, are concerned. It is, therefore, favorably situated to show a 

 high degree of vernal surface warming. 



On the other hand, the surface water of the southern parts of the 

 Labrador Current is constantly being replenished by cold water from 

 the north. It is underlaid by extremely cold water and overlaid by 

 much fog throughout the season. The effects of solar warming show 

 up slowly and it is easy to see w^hy it only warms up 14%° F. on the 

 average during the time in which the Grand Banks surface waters 

 are warming up 22° F. 



The Gulf Stream's small surface warming despite much clear 

 weather can be attributed principally to the fact that its waters are 

 already warm. It is flowing with a large northerly component into 

 cooler regions of decreased sun strength where radiation and other 

 losses can with less and less facility be counterbalanced. 



The area of mixed surface water between the Gulf Stream and the 

 Labrador Current changes position and size rapidly, varying so much 

 from month to month and 3^ear to year that it is hard to say just what 

 its exact increase in temperature is. A fair figure would be one some- 

 where between that of the pure Labrador Current and Gulf Stream 

 surface water, say 13° F. 



Coming back to the 74,000 square sea mile "melting area" it can 

 be seen that, though principally over the Labrador Current, it slightly 

 overlaps the Banks, and extensively overlaps the mixed water oft"- 

 shore. Fourteen degrees Fahrenheit can be taken as a good figure 

 for the total rise of its surface water temperatures during the 100- 

 day ice-patrol season. The warmed waters tend, of course, to remain 

 near the surface of the sea, hence the warming effect decreases rapidly 

 with depth throughout the Grand Banks region. 



Let us assume that the rise of temperature at the 50-foot level in the 

 "melting area" during the ice-patrol season is 10° F., as compared 

 with 14° F. at the surface during the same time. The stations which 

 the ice patrol has taken in the area usually sample the surface, the 25- 



