Acoustic field variability induced by time evolving internal wave fields

A space- and time-dependent internal wave model was developed for a shallow water area on the New Jersey continental shelf and combined with a propaga tion algorithm Eo perform numerical simulations of acoustic field variabili ty. This data-constrained environmental model links the oceanographic field , dominated by internal waves, to the random sound speed distribution that drives acoustic field fluctuations in this region. Working with a suite of environmental measurements along a 42-km track, a parameter set was develop ed that characterized the influence of the internal wave field on sound spe ed perturbations in the water column. The acoustic propagation environment was reconstructed from this set in conjunction with bottom parameters extra cted by use of acoustic inversion techniques. The resulting space and time- varying sound speed field was synthesized from an internal wave field compo sed of both a spatially diffuse (Linear) contribution and a spatially local ized (nonlinear) component, the latter consisting of solitary waves propaga ting with the internal tide. Acoustic simulation results at 224 and 400 Hz were obtained from a solution to an elastic parabolic equation and are pres ented as examples of propagation through this evolving environment. Modal d ecomposition of the acoustic field received at a vertical line array was us ed to clarify the effects of both internal wave contributions to the comple x structure of the received signals. (C) 2000 Acoustical Society of America . [S0001-4966(00)03109-X].