THE PROBLEM 



Determine the effects of the environment on detection 

 and classification of objects in the sea. Specifically, conduct 

 research on the widely observed differences in the water 

 transparency and determine the basis for the turbidity structure 

 of water off Mission Beach, California. 



RESULTS 



1. The turbidity structure of the water off Mission Beach 

 varies greatly in both depth and time. 



2. There is usually a cycle in the distribution of water 

 turbidity corresponding to the tidal cycle. 



3. A relationship was demonstrated between water 

 temperature, internal waves, and turbidity. 



4. The level of maximum turbidity frequently lies at or 

 near the level of maximum temperature gradient. 



5. A sound scattering layer corresponding to the depth 

 of maximum turbidity was observed by means of an upward 

 directed echo-sounder. 



6. Water turbidity is mainly due to concentrations of 

 plankton and detritus in the water. 



RECOMMENDATIONS 



1. Additional studies should be conducted at the NEL 

 Oceanographic Research Tower and in other geographical 

 areas, and the data compared. 



2. For continuous studies of several days' duration, 

 multiple turbidity sensors and suitable continuous recording 

 equipment should be employed. 



3. A more detailed study of acoustical -biological- 

 turbidity relationships should be made to determine the cause 

 of patchiness in acoustic scatterers. 



MBL/WHOI 



0301 DDMOSMfi b 



