MELLEN: SOUND PROPAGATION IN A RANDOM MEDIUM 



We now have the parabolic equation model. We have some rather 

 sophisticated ray models. 



It sounds to me offhand as though it might be feasible to make 

 that kind of a study and see whether the attenuation coefficient re- 

 sults are highly dependent on the model used to reduce the data. Be- 

 cause the data are bound to be good data. 



Dr. Mellen: We rely mostly on the agreement with the FFP, al- 

 though I don't know whether we have used CONGRATS 5 or anything like 

 that yet. 



Dr. Hersey: That, you see, you have right in your own group. 

 But here's a case where we have an excellent data bank. The fact that 

 the work was concentrated in one place is perhaps a strong argument 

 for consistency in the way the work was done. And if we as a 

 community would manage to make use of our several model designs to see 

 how sensitive the reduction of the data is to models, we would at 

 least have a basis for answering some of the worries that were expressed 

 here this afternoon. 



When that has been done we would all have a basis for making an 

 estimate of what we ought to do next. Is it a critical experiment? 

 Or a critical series of experiments? Or are we beginning to approach 

 understanding? 



Dr. S. M. Flatte (University of California, College of Santa Cruz) : 

 I wanted to mention that last summer our group made some parabolic 

 equation runs which attempted to indicate what the scattering in the 

 sound channel would be from internal wave models. I would emphasize 

 that you have to have a model of everything that is happening in the 

 ocean to decide what the scattering is. 



However, it would be at this point rather easy for us to propagate 

 any number of modes through internal waves and find out what the 

 scattering due to that would be. 



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