Impact of shelfbreak fronts on long-range underwater sound propagation in the continental shelf area
Ying-Tsong Lin, Alexey Shmelev, James F. Lynch, Arthur E. Newhall, and Pierre F. J. Lermusiaux

         The dynamic shelfbreak front commonly observed in the continental shelf area has significant impact on underwater sound propagation. Analytical study with an idealized front model has shown that combining inshore refraction from the front and offshore refraction on the sloping shelf, long range propagating sound on the continental shelf will be trapped by the front and form “whispering gallery” modes on the inshore side of the front. In this paper, numerical propagation simulations with three-dimensional normal mode and parabolic approximation methods are implemented to investigate the acoustic impact of a nearly realistic front model. This front model results from the MIT Multidisciplinary Simulation, Estimation, and Assimilation System which assimilated the field measurements collected during the New Jersey Shelf Shallow Water 2006 experiment. Since the front model captures very well the temporal and spatial variability of the shelfbreak frontal system in the field, the numerical propagation simulations presented here are fairly realistic. Horizontal sound refraction due to the shelfbreak front and (subl-mesoscale eddies are observed, and causes part of long-range propagating sound energy to be trapped on the shelf area.

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