SPINDEL: PHASE FLUCTUATIONS, COHERENCE AND INTERNAL WAVES 



Dr. Spindel : Yes. 



Dr. Flatte: But in a random way? 



Dr. Spindel: The randomness comes in because of the randomness 

 of that layer. That layer is a superposition really of many internal 

 waves. 



Dr. Flatte: But the internal wave predicts the average fluctu- 

 ation in one ray or another. It does not predict how the combination 

 will occur unless you assume you know the amplitude of fluctuations 

 and their distribution and then form some kind of a statistical 

 combination. 



Dr. J. G. Clark (Institute for Acoustical Research) : You did 

 not describe internal wave field statistics? 



Dr. Spindel : Yes, and the resulting received signal is really 

 just a superposition, that is, a linear combination of all the rays. 



Dr. Flatte: You assumed equal amplitude? 



Dr. Spindel: Yes. 



Mr. C. W. Spofford (AESD, Office of Naval Research) : I have 

 here three figures that are the results of a numerical experiment 

 which I think bears on these phase statistics. It was stimulated 

 by a question I asked Bob Porter about a year or so ago at an 

 Acoustical Society meeting when I first heard of the technique of the 

 drifting floats, because I was concerned that he was taking out the 

 phase assuming that it was essentially linear in range. And I think 

 we have seen ample evidence today it is not. 



I actually made a numerical calculation using the parabolic- 

 equation program extracting the phase as a function of range at 



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