260 



subsurface water commonly occurs. These latter inversions 

 do not reflect any essential instability of the water column. 



Water Masses and Units 



The water in the bay has been classified according to 

 temperature salinity relationships as follows: 



Shelf Water Mass - 48© to 730F, 33.0 to 33.5 o/oo 



Surface Water Unit - 48° to 73°?, 33.0 to 33.5 o/oo 

 Subunit 1 - 60O to 62°?, 33.5 o/oo 

 Subunit 2 - 64° to 66°F, 33.5 o/oo 



Sewage Field Subunit - 75° to 580F, to 33.4 o/oo 

 Intermediate Subunit - 54© to 570F, to 33.5 o/oo 

 Subsurface Water Unit - 53°F, 33.5 o/oo 

 Slope Water Mass - 46© to 50OF, 33.6 to 34.3 o/oo 

 Basin Water Mass - 430f, 34.3 o/oo 



The seasonal distribution of the various water units shows 

 a biannual variation. The nearshore waters are normally colder 

 than offshore waters in the winter season, November through 

 May, and warmer in the summer, June through October. More or 

 less steady state conditions exist along the Malibu and Palos 

 Verdes coasts. Here cool water is adjacent to shore through- 

 out the year. The conspicuous area of cold water along the 

 Malibu coast is due either to a vertical displacement of iso- 

 therms following a period in which warm surface water is 

 removed from the coast by westerly winds, or to active up- 

 welling. The cold area to the south is due either to an 

 upward displacement of cool water near the coast associated 

 with the presence of a southerly current in that area, or to 



