Experimental Evidence of the Importance of Sub-Bottom Refraction at 206 HZ.
INSTITUTE FOR ACOUSTICAL RESEARCH MIAMI FLA
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Acoustic data obtained using a bottom mounted 206 Hz projector and two bottom mounted receiving hydrophones 8.5 km and 21.8 km distant showed multiple acoustic paths with travel times approximately 30 percent faster than predicted for water-borne propagation. The presence of amplitude modulation with a 6.5 second period indicated that acoustic energy was reflected from the ocean surface before entering the high velocity limestone and coral bottom and being refracted to the receivers. Since received pulses showed little distortion, sub-bottom layers may be modeled as complex impedances at the 206 Hz frequency. The results demonstrate the importance of bottom propagated energy at low frequency and short range. Author
- Physical and Dynamic Oceanography
- Electrical and Electronic Equipment