Ambient sea noise dependence on local, regional and geostrophic wind speeds: Implications for forecasting noise

Abstract

Measurements of ambient sea noise in two regions near Australia are presented as a function of wind speed (a) measured locally (at a buoy, distance about 120 m), (b) measured at weather stations (distances up to 51 km) and (c) predicted from the geostrophic air flow. Estimates of geostrophic winds from atmospheric pressure contours are used in forecasting wind speeds. Good correlation of noise with local wind speed was observed. Poorer correlations were observed between noise and regional wind speeds or those predicted from geostrophic wind speeds: trends were similar but the spread of the data points was greater. Correlations were better when the wind field had minimal influence by the presence of land upwind. The variation of geostrophic wind speed with time generally followed that of the local wind speed but peaks and troughs were sometimes displaced in time by a few hours, accounting for some of the spread of the data. These results suggest that geostrophic wind, and thus forecasts of wind speeds, would be useful in forecasting sea noise.