Matched-field replica vector stability in the winter ocean on the New Jersey (USA) shelf—RAGS03

A measure of the environmental influence on matched-field processing is the temporal autocorrelation of the coherent acoustic field passing through a vertical aperture. The matched-field autocorrelation times provide estimates of the time interval over which matched-field replica vectors will remain valid. In December 2003 the Naval Research Laboratory moored three vertical arrays at ranges of 10, 20 and 30 km distant from fixed 300- and 500-Hz CW acoustic sources. The purpose of the experiment was to measure the relationship of array gain to shelf break fluid processes (RAGS03). Data was recorded continuously for more than 20 days. Range and time dependent temporal autocorrelation times derived from this data will be presented and compared to similar measurements made at the South China Sea shelf break during the ONR AsiaEx01 acoustic propagation experiment. Preliminary RAGS03 results show that matched-field autocorrelation times are shortened during strong wind events and that sound speed fluctuations caused by semi-diurnal tidal processes forced quarter-diurnal fluctuations in the matched-field processor output. [Work supported by ONR.]