Site dependence of wind-dominated ambient noise in shallow water

Abstract

A survey of ambient noise data in shallow water taken under wind-dominated conditions shows substantial differences in spectrum level (often greater than 10 dB) under the same windspeerl and sea-state conditions. This areadependent effect, which is evident even in long-term averaged data, is caused by differences in ocean bottom properties, water depth, and soundspeed profile. Comparisons between those data sets which are accompanied by suitable environmental information and a wind-noise model developed jointly at NRL and SACLANTCEN are shown. The areas in which the data were taken cover a broad range of bottom types, water depths, and sound-speed profiles. Calculated differences in noise level agree well with the measured differences and it is concluded that the model is capable of predicting the effect of the shallow water environment on the spectrum level of wind-dominated ambient noise. We also conclude that commonly used universal ambient noise curves which do not take into account environmental differences are inferior to the model predictions in shallow water.