new approach formulated by Davies ( 1951 ) • This paper has not as 

 yet been studied thoroughly, but in the future the practical 

 applications of this work to the present problem will be 

 evaluated. 



Since the basic assumptions made in the simplified two- 

 layer model predicate the wave to be traveling along the inter- 

 face, a study of the internal wave using these principles must 

 mainly be a study of the oscillations of the thermocline. One 

 may begin by defining the processes which, at any given time or 

 for any period of time, will govern the depth of liie mixed layer, 

 These are: 



a. Seasonal variations - Probably more is known about this 

 parameter than any other because it is strongly reflected in the 

 mean monthly values of the thermocline, which mean values have 

 been published. Illustrations 



of this effect, taken from these publications, are given in fig- 

 ures 12, 13 J and 1)^., Since most of the time-series BT data are 



FIGURE 12. MEAN MONTHLY MIXED LAYER DEPTHS FOR WEATHER SHIP COCA, 52.7°N.,357°W. 



37 



