Geoacoustic parameter estimation using back wave propagation technique

Abstract

The concept of back wave propagation (BWP) is developed as inversion method to estimate ocean geoacoustic parameters where the source location is known. A phase-regulated technique is introduced to increase the sensitivity of the method for low sensitive geoacoustic model parameters. We show theoretically that we can increase the sensitivity by a sensitivity factor /spl alpha/ using the phase regulation procedure. We also show that the spatial resolution of signal energy that is concentrated is increased when /spl alpha/ increases. This leads us to define a criterion based on spatial distribution of signal energy around the true source location. This criterion is formulated based on the spatial covariance of the back propagated pressure field in a window around the known source location. We apply this technique to the real data from the Pacific Shelf experiment that was carried out in the shallow water off the West Coast of Vancouver Island in the Northeast Pacific Ocean. We demonstrate the inversion for estimating three ocean parameters including water depth, compressional speed of the first sediment layer and sediment density.