80 



O 100 — 



120 — 



EAST of SINGAPORE 



WINTER PROFILE 



25 m SOURCE 



RANGE 



1000 

 FREQUENCY, Hz 



4000 



Figure 4.9. Propagation loss for optimum receiver depth vs frequency 

 for ranges of 50, 100 and 1 50 km. East of Singapore winter (positive 

 gradient) profile; source depth 25 m. 





EAST of SINGAPORE 



SUMMER PROFILE 



25 m SOURCE 



/^ 



^ 50 km 



100 



" 



f 





110 



- / 



1 00 km / 



1 



120 



1 1 / 1 1 



1 / 



l\ 1 



1000 



2000 

 FREQUENCY, Hz 



5000 



Figure 4.10. Propagation loss for optimum receiver depth vs 

 frequency for ranges of 50 and 1 00 km. East of Singapore 

 summer profile; source depth 25 m. 



47 



