posed on the periodic variations discussed above, a highly ir- 

 regular pattern results. When these data are subjected to an 

 empirical treatment, there are two difficulties which must be 

 overcome. One is the problem of determining the proper lag 

 factor to employ, because the thermal structure does not reach 

 equilibrium with the sea and wind instantaneously. The other is 

 the fact previously mentioned, namely, that while turbulent mix- 

 ing causes the thermocline to get deeper, ceasing of the turbu- 

 lence does not necessarily cause the thermocline to become shal- 

 low. 



f , Empirical investigation of thermocline depth - With 

 all the effects described above existing at the same time and 

 in view of the limited data available, it would be difficult 

 to correlate any one of these single parameters with the varia- 

 tion in the thermocline because of the effect of the other fac- 

 tors. This procedure has been attempted without success in cor- 

 relating the depth of the thermocline with sea and wind conditions 

 alone. 



On the other hand, on the basis of our present knowledge of 

 the thermal structure. It can be shown that it would be just as 

 hopeless to attempt to include all of the parameters in one re- 

 lationship. This would amount, for all practical purposes to 

 predicting the depth of the mixed layer for one particular time. 

 Such a relationship might be written as follows: 



48 



