Impacts of wind and river discharge on the variability of mid-frequency sonar in Dabob Bay

Dabob Bay is a long, narrow bay in Washington with a depth of 195 m at its center. In January, storms consistently come from the southwest creating waves that run along the long axis of the bay making it a natural laboratory in which to study their impact on sound propagation and reverberation. In January 2020, the Autonomous Reverberation Measurement System (ARMS) was deployed in the northern end of the bay and transmitted pulses every 20 s over 8-hperiods to a vertical line array deployed at a range of 5km and in line with the prevailing wind direction. The sound speed profile during the experiment was upward-refracting with a layer of cold, fresh water at the surface that varied in thickness from 5 to 19 m due to rain-driven changes in river flow into the bay. The changes in the layer thickness produced 10–15 dB changes in transmission loss at time scales on the order of 30 min while the surface roughness produced ping-to-ping variations on the order of 5–10 dB. This talk focuses on efforts to capture these environmental impacts on propagation and reverberation in acoustic models. [Work supported by the Office of Naval Research.]