HAMILTON: TIME VARIATIONS OF SOUND SPEED OVER LONG PATHS IN THE OCEAN 



Dr. R. P. Porter (Woods Hole Oceanographic Institution) : Were 

 you able to resolve any other arrivals besides the axial arrival? 

 In other words, could you say there were specifically other paths 

 that stood out that might have been rays that were going through 

 water with a higher sound speed? 



Mr. Hamilton : We occasionally would see it on the first group 

 of arrivals when we had a suspended hydrophone. Within a group we 

 would see the individual arrivals corresponding to the up- and 

 down-going paths on both ends. These were apparent for the earliest 

 orders, and then they start to get closer together, effectively over- 

 lapping. 



Dr. Porter: Would you see this arrival structure then build up 

 in the final arrival? In other words, could you analyze those shots 

 in terms of the individual arrivals themselves prior to the axial 

 arrival, because if you could do that, then you could possibly look 

 at some of the average sound speeds through the remaining part of 

 the water column. 



Mr. Hamilton: Most of our work was at ranges like a thousand 

 miles, and the cycling of the groups is about 30 miles, so we are 

 talking about 30 of the groups building up into the final peak. 

 We might see the first and the second, but after that it pretty much 

 ran together. It didn't look to us at the time like an interesting 

 problem to work on, and we didn't look at it. 



Dr. W. B. Moseley (Naval Research Laboratory) : In your data, the 

 temperature variability at neither the source nor the receiver 

 appears to directly correlate with the travel-time variability. 

 However, if you were dealing with the same water mass type throughout 

 the range, would you expect the statistics at either of the end 

 points to correlate with the statistics of the arrival time? 



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