High-frequency One-way Propagation Experiments in Portsmouth Harbor, NH


Portsmouth Harbor is a shallow water estuary with 3-m tide heights and 2-m/s tidal currents, exhibiting strong mixing between ocean water and several fresh water inputs. In order to help characterize the limitations for underwater acoustic positioning systems in this environment, high-frequency 40 kHz one-way acoustic propagation measurements were made at ranges up to 1 km in an area where the maximum depth reached 25 m. Synchronized acoustic transmissions were made from a bottom mounted projector as well as from a near-surface projector mounted on a moving research vessel. The signals were received at a pier-mounted hydrophone. Measurements of signal levels and arrival times show strong signatures from a variety of phenomenon including changes in tide height, changes in sound speed gradients in response to the tidal forcing functions, and turbulent mixing in the water. Each of these will be discussed in relation to signal fluctuations and constraints on measuring pulse arrival times.


Center for Coastal and Ocean Mapping

Publication Date


Journal or Conference Title

Meeting of the Acoustical Society of America (ASA)

Conference Date

Nov 10 - Nov 14, 2008

Publisher Place

Miami, FL, USA


Acoustical Society of America

Document Type

Conference Proceeding

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