SPINDEL: PHASE FLUCTUATIONS, COHERENCE AND INTERNAL WAVES 



Dr. Flatte: That is right. 



Dr. Spindel: That is true. We are aware of that. We are also 

 aware of the sensitivity of the model to selection of that angle, (b . 



g 



Even if you were to assume that that layer were not in a particularly 

 difficult area (where the rays turn, for example) but were lower, the 

 model is quite sensitive. Angles are quite shallow at which rays 

 enter and leave the layer. 



We are not really propounding the theory as one which explains 

 all the interactions between internal waves and acoustics. But what 

 we wanted to point out was that the environmental effects of internal 

 waves are mirrored in the acoustic phase. And I think we can do that 

 although we cannot predict absolute levels, which is basically what 

 that factor is. 



Dr. Flatte: 1 agree with you completely and that, in fact, 

 the results do show the internal waves compare quite favorably with 

 these data. I would like to make one more comment that has to do 

 with the one I made last night about the difficulty with computer 

 codes. 



Roger Dashen and Walter Munk did an integral over the ray path 

 and found that in fact for our case the main contribution came from 

 the turning point. 



The theoretical prediction which was given to me to compare with 



what came out of the computer code was that if you plot the riiis phase 

 fluctuation, as a function of range, you expect rather small fluctu- 

 ations before the turning point. And as soon as you reach the area 

 of the turning point, there should be a rather sharp jump. When I 

 looked at the computer code, I did see a reasonably small fluctuation 

 up until the turning point, although the quantitative agreement has 



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