b 100 



1 — I I t 



T~rT 



STRAITS OF SICILY 

 WINTER PROFILE 

 500 m BTM DEPTH 

 25 m SOURCE 



J I I ' I I I 



400 500 1000 



FREQUENCY, Hz 



2000 3000 



Figure 4.18. Propagation loss for optimum receiver depth vs frequency for 

 ranges of 50, 100 and 150 km. Straits of Sicily winter profile, 500 m 

 bottom depth; source depth 25 m. 



o 110 



100 200 



FREQUENCY, Hz 



300 400 500 700 1000 



Figure 4.19. Propagation loss for optimum receiver depth vs frequency for 

 ranges of 50, 100 and 150 km. Straits of Sicily summer profile (downward 

 refracting), 500 m bottom depth; source depth 25 m. 



55 



