There are also 4- to 5 day oscillations of the thermocline, which have 

 counterparts in the wind and are a result of Ekman transport. 



The Ekman transport theory is formulated assuming that the wind 

 and current systems have attained steady-state conditions. To examine 

 the application of the wind transport theory to relatively short-term 

 phenomena, a phase comparison was made between the average diurnal 

 thermocline depth cycle and the average diurnal wind cycle for the 

 month of August, It was found that the depth changes lagged behind the 

 wind changes by 14 to 16 hours. Using this value as an approximation of 

 the response time of depth to wind changes, we can rewrite the linear 

 dependence equation as: 



D^ ^ = 36 - 2,6 W^_25 Equation (l) 



where 



D^^^^ 1^ is the wind-predicted depth in feet to the center of the 

 thermocline at time t, and 



Wt_i5 = 1/4 (2Wt_i5 + Wt_i4 + W^.ie) 

 where 



^t-x i^ ^^^ hourly average wind component from the WNW at x hours 

 prior to time t. 



Wind Direction 



To confirm that the raising and lowering of the thermocline 

 (Fig 4) are governed by the wind component parallel to the coastline, 

 and do not correlate better with the wind normalized along some 

 slightly different axis, a directional search was made in which the 

 depths predicted by equation 1 were compared with the corresponding 

 measured thermocline depths at hourly points throughout a 33-day period. 

 The results, presented as the standard deviation between the measured 

 and predicted points as a function of normalization direction, are 

 shown in Figure 5. 



121 



