Acoustic thermometry of ocean climate (ATOC)

Abstract

The purpose of ATOC is to monitor ocean variability over scales exceeding 1 year and 5000 km, using the method of ocean acoustic tomography. ATOC takes advantage of the favorable condition in the sound channel for low-frequency propagation. By forming long-range averages, the very intense mesoscale variance is reduced by two orders of magnitude to permit the detection of the relatively weak climate signals. Results of 15 months of transmissions from a source off Monterey, California will be shown. The exploration of the oceans by acoustics dates back to the use of acoustic depth meters and the navigation of drifting buoys. With the modern development led by Brekhovskikh, the move is toward matched-field methods which attempt to interpret the entire recorded sound field in terms of the pertinent ocean parameters.