OCEANOGRAPHIC INFORMATION FOR SUBMARINE CABLES 1085 



3.7 



UJ 



Q 



<3.6 



Z 



3.5 



o 



LU 



O 



LU 

 Q 



Z 3.3 



a: 



I- 3.2 

 < 



CE 



LU 

 CL 



5 3.1 



LU 



H 



3.0 

 1928 





1932 1936 1940 1944 



YEAR 



1948 



1952 



Fig. 23 — Variation of mean temperature at 1,500-meter depth in the .southern 

 Labrador Sea at about the point indicated in Profile 2, Fig. 21. 



probably small. At one time it was assumed that the ocean temperature 

 in depths exceeding 1,000 meters remained constant. As more informa- 

 tion is gathered it is becoming evident that changes in temperatures 

 have occurred in deep water, but neither the mechanism nor the time 

 scale of the changes is as yet completely understood. 



Due to the virtual absence of deep sea bottom temperature observa- 

 tions it is not possible to determine changes in temperatures by compari- 

 son of repeated measurements at approximately the same position. In a 

 few limited areas repeated observations have been taken to depths of 

 about 3,000 meters. All observations for one such area northeast of 

 Newfoundland have been studied in search of long-term trends. It has 

 been found that the water temperature between 500 and 2,000 meters 

 in this area is nearly constant, both vertically and laterally over a wide 

 area during any one year. It is thus meaningful to compare the tempera- 

 ture at 1,500 meters depth for a series of j^ears. Fig. 23 shows the results 

 of this comparison which indicates a 0.6°C increase between 1928 and 

 1949, and a 0.4°C drop from 1949 to 1954. This curve resembles the 

 air- and sea-surface temperature averages for Atlantic-coast stations 

 during the same years. 



In the area between Labrador and Greenland a moderate number of 

 near-bottom temperature measurements have been made since 1928. 

 No systematic curve can be drawn but it seems fairly certain that bot- 



