Estimating geoacoustic properties of marine sediment on the New Jersey continental shelf from broadband signals
Yong-Min Jiang and N. Ross Chapman

         This paper presents geoacoustic inversions of broadband signals collected in the Shallow Water 2006 Experiments off the coast of New Jersey. An L-shaped array was deployed on the top of a sand ridge, in 70 m of water. The acoustic source was maintained at a distance of 190 m from the vertical leg of the L-shape array, and lowered from 10 to 60 m in 10 m intervals in the experiment. Two sets of chirps, low frequency (100-900 Hz) and midfrequency (1100-2900 Hz), were transmitted with approximately the same experimental geometry. The water column sound speed profiles were measured at the source position. This study examines the sediment information content from different frequency bands recorded on the vertical leg of the L-shape array. Because the chirps have different temporal resolutions and energy penetrabilities in the sediment, the recieved signals exhibit different bottom structures at different frequency bands. Travel time geoacoustic inversions are carried out at both frequency bands using signals from the resolvable reflections from the sediment layers. The variation in the oceanic sound speed profile is parametrized in terms of its characteristics and included in the inversion.

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