Influence of atmospheric pressure gradient on under‐ice ambient noise

Abstract

Correlations exceeding 50% have been measured between wind speed and under‐ice ambient noise levels in one‐third octave bands. Using barometric data, meteorologists derive geostrophic wind from the atmospheric pressure gradient. The present research involved measuring correlations between the magnitude of the atmospheric pressure gradient and under‐ice noise levels in one‐third octave bands to determine if noise‐prediction models could be developed. Then, one could use meteorological data to generate “isonoise” contour maps for the Arctic Ocean similar to isobaric maps. Barometric and ambient noise data were available from a trio of buoys drifting in the Beaufort Sea for over a year. For one‐third octave bands centered at 3.2, 10, and 32 Hz, correlations with the air pressure gradient magnitude were normally 50% or better. At 1000 Hz the correlation was nominally 25%, a result attributed to higher propagation loss at that frequency and the need for knowledge of pressure gradient on a smaller scale. Predictive models were derived for each frequency for each of the four annual sessions. [Work supported by ONR.]