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Observations Of High Frequency, Long Range Acoustic Propagation In A Harbor Environment, Michelle Weirathmueller, Thomas C. Weber, Larry A. Mayer

Center for Coastal and Ocean Mapping

The positioning and navigation of AUV's in harbor environments using underwater acoustics is complicated by shallow waters, long propagation distances, and complex oceanographic features. This paper reports on high frequency (40 kHz) acoustic measurements made in Portsmouth Harbor, NH, USA, which is an estuary containing several riverine inputs and a strong tidal flow (2+ knots). A one-way propagation experiment was conducted at the mouth of the harbor for propagation distances up to 100 water depths. Strong signatures of a variety of phenomenon were observed in the acoustic signal levels, including tidal heights and currents, turbulent mixing, and wind/wave action. The …