Geoacoustic Inversion in Shallow Water

The goal of this work is to perform geoacoustic estimation by solving inverse problems that use physics of sound propagation and statistical signal processing. We will analyze SW06 and SBCEX data attempting to perform near-range inversion with broadband time-series. The SBCEX data have been made available very recently and lfm receptions at the MPL vertical line arrays are optimal for such an analysis. Linearization will be carried out with the sound speed in the water column being estimated through EOFs and their coe cie'nts. In addition to source location, water depth, and sound speed in the water column, we will now estimate sediment properties such' as sound speed and thickness using arrival time densities. We will then investigate the potential of using amplitude probability de'nsities to estimate sediment attenuation. Furthermore, we will extend the direct inversion method developed by Lin and Michalopoulou'' linking a reflection coefficient to the sound speed in the sediment, ''catching'' all non-linearities at the sediment interfaces. A c''hallenge is that the Hankel transform, a key element of the method, performs poorly when applied to noisy pressure data. We will wor'k on remedying this problem. We will also work on estimating the density profile in addition to sound speed.