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The Impact of Very High Frequency Surface Reverberation on Coherent Acoustic Propagation and Modeling
Marine Physical Laboratory, University of California San Diego La Jolla United States
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The long-term science objective is to develop a physical model of high-frequency scattering of underwater acoustic signals from the sea surface under a range of wind-driven conditions. The model will focus on signal coherence, and second-order amplitude and Doppler statistics. A second long-term goal is to measure and model very high frequency underwater sound generated by processes at the sea surface, relevant to the high-frequency underwater acoustic communications problem. The scattering of sound from the sea surface is important for the operation of underwater sonar and underwater acoustic communications systems. Studies of low to mid-frequency surface reverberation have a long history, but studies of very high frequency 300 kHz surface scattering in the literature are rare. The physics of very high frequency VHF scattering is expected to be strongly dependent on wind speed, which controls surface roughness and wave breaking, which injects bubbles into the ocean. The amplitude, Doppler spread and temporal coherence of VHF scattering is important for the performance of high frequency sonars and underwater communications systems in operating scenarios where energy from the sea surface cannot be screened. The generation and propagation of high frequency underwater noise is also important to VHF underwater acoustic communications.
APPROVED FOR PUBLIC RELEASE