46 

 The Seasonal Character of Shelf Water Units 



The temperature characteristics of the various shelf water 

 elements from June 1955 to June 1956 are shown in Figures 15 

 to 21. Only the vertical relationships of the units and sub- 

 units have been scaled. Horizontal dimensions have been 

 ignored for simplicity. In the following discussion only a 

 few representative temperature distributions are described in 

 detail. 

 June 1955 



In June 1955 a thermal boundary existed between the Sur- 

 face and Subsurface Water Units, consisting of successive 

 layers of nearly isothermal water and forming a series of 

 distinct steps. The Surface Unit had a temperature range of 

 from 60°F to 66°F inshore, and was subdivided into at least 

 two subunits (Fig. 15). 



Subunit 1, which covered the greatest area, had a tem- 

 perature range of from 60° to 62° and an average thickness of 

 approximately 20 feet. It reached a maximum thickness of 50 

 feet in the central portions of the bay. This water was pro- 

 bably moved inshore by the prevailing winds where it mixed 

 partially with underlying water and partially with nearshore 

 water. Subsequently, it was overlapped by the warm nearshore 

 Surface Unit in the central shore margins of the bay. 



The nearshore warm layer (Subunit 2) had a temperature 

 range of from 64° to 66°, which was apparently the result of 

 increased heating in shallow water and of heat contributed by 

 effluent and warm water discharge from the Edison Company Steam 



