High-frequency ocean ambient sound: Estimating wind speed using a 150-kHz ADCP

Abstract

Ocean ambient sound is well correlated with wind speed for frequencies between 2 and 50 kHz. At higher frequencies it is conventional wisdom that thermal noise will dominate the wind-generated sound. Data are presented showing that background sound levels recorded by a 150-kHz ADCP demonstrate strong correlation with wind speed and with independent measurements of ambient sound (below 70-kHz frequency). When the ADCP data are calibrated using scaling factors available from the manufacturer, the observed 150-kHz sound levels are consistent with the expected ≂20 dB/decade slope of the high-frequency ambient sound spectrum. Using calibrations based on two independent deep ocean deployments, 150-kHz ADCP background sound levels can be used to estimate ocean wind speeds with an accuracy of 1.5±1.5 m<th>s−1 for wind speeds up to 15 m<th>s−1. [This research was funded by R. D. Instruments.]