119 



temperature topographies are more complex than in the colder 

 months of the year. This, of course, is to be expected due 

 to greater density differences between the surface and sub- 

 surface water in the warmer season. 



A typical surface is shown in Figure 55, which depicts 

 the 61°F isothermal surface on July 6, 1955. The normal up- 

 welling pattern occurred in the northern part of the bay, 

 indicating a flow into the area off Santa Monica. A conver- 

 gence was found off Venice coupled with a divergence to the 

 south opposite El Segundo. Water was obviously leaving the 

 bay to the south, and the flat gradient offshore was indicative 

 of wind dominance over the drift of the water. The subsurface 

 topography on this day had a nearly identical pattern which 

 shows the stability of water motion over the continental 

 shelf following extended periods of stable meteorological 

 conditions (Fig. 56). 



The constant nature of the cold water along the Malibu 

 shore, and the variation from simple to highly complex tem- 

 perature surfaces that occur over short periods of time are 

 shown in Figures 57, 58, 59, 60, 61, 62, and 63, which show 

 thermal topographies for August 10, 18, and 24, 1955. On 

 each day, the colder units discussed previously as being in 

 a more or less steady state condition in the north and south 

 borders of the bay were dominantly present. On August 18, 

 the upwelling water from the north extended into the bay as 

 far south as Manhattan Beach; a temperature pattern which 

 repeated itself in March 1956. On each occasion, winds stronger 



than Force 4 had blown quite steadily for the two to three pre- 

 ceding days. 



