BROIVNING: ENVIRONMENTAL FACTORS AFFECTING LOW FREQUENCY 

 PROPAGATION IN THE OCEAN 



Once we had this, we thought we should extend it to typical deep- 

 ocean environments and see what would be predicted about significant 

 leakage out of a sound channel . 



Figure 14 shows two profiles used for these predictions. One 

 corresponds to the KIWI 1 experiment which Bannister has described 

 and which was performed in the South Pacific. The other is the ATOE 

 experiment, with a run east from Bermuda, which produced a large 

 amount of good data appropriate to our comparisons. 



We wanted to see where channel leakage becomes significant as a 

 function of bottom depth and as a function of frequency. Also, where 

 is there a significant difference between these two profiles in terms 

 of propagation loss? 



Figure 15 shows the bottom loss curves that we used. We felt 

 for this case that we need not be as sophisticated as we were before, 

 so we assumed a relatively simple form, since the effect would be the 

 same. 



Figure 16 is the comparison of propagation loss for the ATOE and 

 KIWI profiles. We limited the depth for the KIWI profile so that both 

 profiles had the same depth, 10,000 feet. Figure 16 is for 25 Hz, 

 with both source and receiver at the sound channel axis. For KIWI, 

 the axis depth was 3,000 feet, and for ATOE 2,700 feet. 



As you can see, in terms of average loss, these curves are 

 practically identical. The conclusions for our purposes was that 

 for average propagation loss, which would, of course, result in 

 attenuation along the sound channel axis, we could treat ATOE and 

 KIWI as the same. 



786 



