Comparison of wind driven ambient noise in shallow and deep-water ocean environments

Abstract

Measured sound pressure time series in shallow and deep-water ocean environments are used to investigate the character of wind-generated noise over a range of wind speed of 2–40 knots and a frequency band of 10–3,000 Hz. In 2006, acoustic data were collected during tropical storm Ernesto off the New Jersey continental shelf in shallow (70 m) water. Ambient noise from these data is compared to deep-water measurements at several locations in the Northwest and the Northeast Pacific. The results also are compared to previously reported measurements by [Kuperman and Ferla (1985)], [Wenz (1962)], and others. The analysis includes a technique for separating background shipping noise from the wind-induced component of ambient noise. The system electronic noise floor and other extraneous sources of noise are evaluated to assure that the ambient noise measurements are not corrupted. Physical mechanisms examined include a wind-saturation effect that limits the ability to acoustically monitor distant storms and the effect of shallow water propagation on the character of wind noise. The identification of the distant shipping part of the spectrum allows for inferences to be made on the low frequency part of the ambient noise spectrum. [Work supported by ONR.]