theraocline as determined by several BT obs over at least a 2-hour period. 



METHOD OF ANALYSIS: 

 The method will be by Fourier analysis as follows, in addition to 

 single station power spectrum analysis. Four assumptions are made: 



1. The three resistance thermometers are located at the same 

 depth near the average mid-depth of the thermocline and are sufficiently 

 restrained from swinging as a pendulum to maintain a fixed position despite 

 horizontal currents. 



2. The vertical movement of the thermocline is never great 

 enough to cause the sensors to be in either the mixed surface layer or in 

 the bottom layer of small vertical temperature gradient. 



3. The vertical temperature gradient within the thermocline 

 is constant. 



4. Progressive internal wave components in the area have 

 infinite crests of constant amplitude but each component moves indepen- 

 dently. 



Under these assumptions, the temperature measured by each thermometer 

 during an interval of record "T" can be approximated by a Fourier Series 

 plus a constant term: 



T(x,y,t)=T + IC n cos(K m X + K 2n y--^^-S n ) 

 n=l i 



where: K in + K 2n = ^n = Xn = square of wave number of nth component 



\ n = wave length of nth component 



K ln = K n cos0 n 



K 2 n =K n sin0 n 



n = direction of normal to n^" infinite crested wave component 



Cn = Op + tip = square of amplitude of nth component 



S n = tan -1 n /a n - phase of n* n component 

 33 



