85 



Redondo, therefore, the northwest wind causes the surface 

 water to be driven offshore resulting in mild upwelling along 

 the coast. The upwelling action is intense because of the 

 broad shelf opposite the shore, so the thermal gradient is 

 usually gentle, the surface water nearshore rising from only 

 about 20 or 30 feet. Thus, the seaward flow, when it occurs, 

 is not strong and does not cancel water motion to the east, 

 although certainly it must reduce its velocity to some extent. 

 Under some wind conditions the surface water is driven from 

 the bay along the western shores of the Palos Verdes Hills. 

 More commonly, though, it is caught between Redondo and Palos 

 Verdes Point until a wind shift or a varying current condi- 

 tion causes it to be redistributed. 



In the late spring the dominant wind pattern along the 

 southern California coast shifts to the west and southwest. 

 The resulting surface water flow causes warmer and lighter 

 water to pile up along the bay shoreline, particularly in the 

 southern part near Redondo (Figs. 28 and 29). The temperature 

 of the water is further increased by heating in the shallow 

 nearshore zone and the addition of heat from man-made sources 

 (Fig. 30). This deepens the warm surface unit and causes an 

 expansion seaward resulting in a gradient current flowing to 

 the north. Many variations in the size, temperature, location, 

 and intensity of the nearshore warm water obviously result 

 from the varying winds and the magnitude of solar insolation. 

 Even so, the consistency of this summer characteristic is 

 readily apparent. 



