Diamond Shoals Lightship (Figure 16, Table 16) 



Due to the great range in temperature change at Diamond Shoals, the 

 depth-time profile of temperature is drawn in five degree isotherms, rather 

 than the one degree isotherms of other figures. 



The dominance of Virginian coastal water at this station during the 

 late winter and spring of 1958 is the striking feature here. From 

 February to mid-May, 10 day mean temperatures throughout the water column 

 and salinities, both surface and bottom, fall far below the mean for the 

 period of record. As has been stated under the section Surface Temperature , 

 this phenomenon is undoubtedly the result of the weather pattern prevailing 

 during the period. Minimum temperatures, both surface and bottom occurred 

 in late March, when surface values were nearly 20 F below the mean. Recovery 

 was rapid, but salinities clearly show the continued dominance of coastal 

 water at the surface through June at least. Vertical temperature structure 

 appeared in mid-May, at which time bottom salinities reached approximately 

 36.00 °/oo. During July, August and early September surface temperatures 

 were above the mean; from mid-September through mid-November, however, both 

 temperature and salinity at the surface fell off sharply. After a brief 

 rise in early December, the year ended with isothermal water somewhat 

 colder than normal. 



Throughout the year, surface temperatures and salinities were consistently 

 below the readings for 1956 and 1957; for comparison the values for the three 

 years in question are given below in terms of annual means, 



1956 1957 1958 



Surface temperature: 67.0°F 72.8 F 6A.0 F 



Surface salinity: 33.76 °/oo 35.27 °/oo 33.07 °/oo 



90 



