The semidiurnal cycle in tide 

 height and the diurnal cycle 

 in wind direction and speed 

 are both reflected in the 

 depth of the thermocline. The 

 graphs show a 3-day com- 

 parison. Vertical lines are 4 

 hours apart. 



ljP 30 



E it 40 



d X 50 



O Z 60 



\v jr VvA^ 



00 04 08 12 16 20 24 04 08 12 16 20 24 04 



12 16 20 24 



WIND-PREDICTED 

 DEPTH* 



The power spectra reveal 

 peaks at 4.5- and 1-day 

 cycles in both wind-predicted 

 thermocline and measured 

 thermocline depths. The tide 

 is solely responsible for the 

 half lunar cycle peak in the 

 observed thermocline depth. 



MEASURED 



-THERMOCLINE 



DEPT 



■Vi LUNAR DAY 



/vVw^N 



100 40 30 20 15 13 11 9 



PERIOD (HRS) 



The tide-wind-thermocline re- 

 lationship makes it possible 

 to predict thermocline depths 

 from wind speed and direction 

 and semidiurnal tide level. A 

 plot of the measured thermo- 

 cline depths averaged over 30 

 days shows a close agree- 

 ment with predicted thermo- 

 cline depths. (Standard devia- 

 tion of hourly values is ± 13 

 feet, standard deviation of 

 daily values is ± 6 feet). 



30 

 0000 



0600 



1200 

 TIME 



2400 

 31 



