4.7 Propagation loss for optimum receiver deptli vs frequency for ranges of 50, 

 100 and 1 50 km. Strait of Juan de Fuca summer (non-positive) profile; 

 source depth 25 m ... 44 



4.8 Propagation loss for optimum receiver depth vs frequency for ranges of 50, 

 100 and 150 km. Strait of Juan de Fuca fall profile; source depth 25 m ... 45 



4.9 Propagation loss for optimum receiver depth vs frequency for ranges of 50, 

 100 and 150 km. East of Singapore winter (positive-gradient) profile; 

 source depth 25 m ... 47 



4. 1 Propagation loss for optimum receiver depth vs frequency for ranges of 50 

 and 100 km. East of Singapore summer profile; source depth 25 m ... 47 



4. 1 1 Propagation loss for optimum receiver depth vs frequency for ranges of 50, 

 100 and 150 km. Lands End winter (positive-gradient) profile; source 

 depth 25 m ... 49 



4. 1 2 Propagation loss for optimum receiver depth vs frequency for ranges of 50, 

 100 and 150 km. Lands End summer profile; source depth 25 m ... 49 



4. 13 Propagation loss for optimum receiver depth vs frequency for ranges of 50, 

 100 and 150 km. Korea Strait winter profile; source depth 25 m ... 50 



4.14 Propagation loss for optimum receiver depth vs frequency for ranges of 50, 

 100 and 150 km. Korea Strait winter profile without the top sediment 

 sand layer; source depth 25 m ... 51 



4. 1 5 Propagation loss for optimum receiver depth vs frequency for ranges of 25 

 and 50 km. Korea Strait summer profile without the top sediment sand 

 layer; source depth 1 00 m ... 5 1 



4. 1 6 Propagation loss for optimum receiver depth vs frequency for ranges of 50, 

 100 and 150 km. Straits of Sicily winter profile, 165 m bottom depth; 

 source depth 25 m ... 54 



4. 1 7 Propagation loss for optimum receiver depth vs frequency for ranges of 50, 

 100 and 150 km. Straits of Sicily summer profile, 165 m bottom depth; 

 source depth 25 m ... 54 



4. 1 8 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 ... 55 



4. 1 9 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 



4.20 Comparison of propagation loss for optimum receiver depth vs frequency 

 results for four sites and the 50 km range; source depth 25 m (winter 

 profiles) ... 56 



4.21 Comparison of propagation loss for optimum receiver depth vs frequency 

 results for four sites and the 50 km range; source depth 25 m (summer 

 profiles) ... 56 



4.22 Bottom reflection loss vs grazing angle for the four sites at frequencies 

 of 200 and lOOOHz. , . 57 



4.23 Bottom reflection loss vs grazing angle for the North Sea site and 

 frequencies of 225, 250 and 275 Hz ... 58 



4.24 Comparison of propagation loss for optimum receiver depth vs frequency 

 results for the 50 km range (winter profiles) ... 60 



4.25 Comparison of propagation loss for optimum receiver depth vs frequency 

 results for the 50 km range (summer profiles) ... 61 



