BROWNING: ENVIRONMENTAL FACTORS AFFECTING LOW FREQUENCY 

 PROPAGATION IN THE OCEAN 



And we found it was just like a regular sound channel. It's 

 amazing. It's just a question of experience. 



This is what we found out. Shallow channels act like deep ones 

 for most frequencies, except when you get low. 



Dr. Marshall: So what you're saying — and this is in question 

 form — is that the Hudson Bay data — which I think was the first 

 slide you put on the screen -- really included only that energy 

 which was in the axial RR mode? Is that right? 



Dr. Browning: That's what we believe. We can compare peak 

 arrivals versus taking the energy of the whole envelope. We do 

 this too. The cheap way, of course, with sound channels is to take 

 the peak arrival because the axial ray is largest and it keeps by 

 itself. But when we get in Bannister's area that's another problem 

 because they find situations where the axial arrival doesn't come in 

 last. 



And so the question is: What if you move between zones where this 

 arrival starts falling off? That's another problem to think about. 



799 



