80 



90 



110 



130 



NORTH SEA INTERMEDIATE PROFILE 

 25 m SOURCE 



100 



200 300 500 700 



FREQUENCY, Hz 



1000 



Figure 4.3. Propagation loss for optimum receiver depth vs 

 frequency for ranges of 50, 100 and 150 km. North Sea 

 intermediate profile; source depth 25 m. 



FREQUENCY 

 150 Hz 



NORTH SEA SUMMER PROFILE 



25 m SOURCE DEPTH 

 100 km RANGE 



100 90 



PROPAGATION LOSS, dB 



Figure 4.4. Propagation loss vs receiver depth for the frequencies of 150, 

 300 and 600 Hz; North Sea summer profile; source depth 25 m. 



41 



