HANNA: DESIGN OF TRANSMISSION LOSS EXPERIMENTS 



You don't deny this in regard to the series of convergent zones 

 systems? 



Dr. Hanna: No. I think the only point I would make here is that 

 the caustic of this convergent zone occurs in the sediment, not back 

 up at the surface. 



Dr. Schulkin: No, no. Just like your regular convergent zone. 

 You have got focusing near the surface of the regular convergent zone. 



Dr. Hanna: Let me make just one further statement. Whatever 

 focusing is accomplished by this sound velocity structure should be 

 reflected in the ray tracing calculation; that is, the essence of 

 that calculation is to compute the spreading loss along that ray 

 along with whatever focusing the environment creates. 



The curves that I showed you were made based on those kinds of 

 computations. So, in my construction, if there is any focusing along 

 that ray from whatever mechanism, it is in the computation. 



It is in the curve that I call the rms sum of intensities which 

 was constructed from the computed intensity along each of those paths. 



Dr. Schulkin: Phasing is very important and this rms combination 

 of your four rays — that's not what Will does anyway, as far as the 

 analysis goes, except for individual arrivals. I don't know why you 

 did that. The rms summation before arrival is not what Will analyzes 

 in his data. 



Dr. Hanna: That is a very important point. 



Dr. Hersey: I am going to take a chairman's privilege and 

 suggest that John go on to his next point and say that we have pin- 

 pointed a problem with which we had better deal. 



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