Geoacoustic parameter estimation using a back-wave propagation technique

Abstract

The concept of back-wave propagation is developed as an 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. In this procedure, a sensitivity factor is varied to enhance the phase changes due to model and environmental mismatch. It is shown that the spatial resolution of signal-energy concentrated at the true source location is increased when the sensitivity factor increases. This leads us to define a criterion based on spatial variance of signal energy around the true source location. This technique is applied 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. The inversion for estimating three ocean parameters including water depth, compressional speed of the first sediment layer, and sediment density is demonstrated. A way to reduce the three-dimensional search to three one-dimensional searches is proposed by exploiting the fact that the pressure field has different sensitivity with respect to these parameters. The replica or modeled fields used in this section are calculated using ORCA.