Amplitude Modulation of an Acoustic Wave Propagating Near the Ocean Surface.
NAVAL POSTGRADUATE SCHOOL MONTEREY CALIF
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Sixty kHz CW sound was propagated parallel to and near the ocean surface adjacent to an array of four thermistors, a salinometer, a sound velocimeter, a turbulent velocity probe, and a wave-height probe in order to investigate the statistics and environmental causes of amplitude modulation. The temporal variations of the sound amplitude were studied during four twenty-minute runs over a range of 2 meters at varying depths from near the surface to 14 meters during sea-state one conditions in water of 16 meters-depth. Analysis indicated mean percentage amplitude modulation of approximately 5 with a variance of approximately 10-3. Author