Diamond Shoals Lightship (fig. 17, table 17)-- 

 Because of the complicated thermal structure 

 at Diamond Shoals, marked by rapid changes, 

 the profile of temperature is contoured for 

 every 5 F. 



The low surface water temperatures in 

 March, which represents the passage of coastal 

 water southward over the Shoals, has occurred 

 every other year during the winter months 

 since 1956 when these observations began; 



90 



in 1957 and 1959 no such breach of the 

 temperature barrier appeared. The remainder 

 of the year showed no marked deviation from 

 the mean for this station. The relatively cold 

 November and warm December is a reversal 

 of the trend at positions further to the north. 

 The bottom temperature maximum, 77.8° in 

 early October, is the highest for the period 

 1956-60. Wide salinity fluctuations as shown in- 

 the figure are normal here. 



80 



70 



Lu 



3 



£ 60 



5 



Lu 



50 



40 



f=N- 



SURFACE T. °F. 





 20 

 40 



60 



I- 



Uj 

 UJ 



U. 80 



S ioo 



0. 

 Uj 

 Q 



120 



140 



160 



180 



1 i I 



60° 



>65° 



50° 

 60* 



60° 



38.0 r 



-J 



<o 32.0 



30.0 



BOTTOM S.%< 



JAN. FEB. MAR. APR. MAY JUN. JUL. AUG. SEP. OCT. NOV. DEC. 



Figure 17.— Diamond Shoals Lightship. (Dashed line in upper diagram mean for period 1923-56.) 



47 



