Simultaneous inversion of seabed and water column sound speed profiles in range-dependent shallow water environments.

Abstract

It is well known that the properties of the water column and seabed affect acoustic propagation in shallow water. As a result, numerous inversion schemes have been developed to estimate environmental properties. Many of these algorithms address the problem of estimating properties of the seabed alone, while assuming properties of the water column are known. An example of such an inversion scheme is perturbative inversion which uses modal wavenumbers to obtain sound speed in the seabed as a function of depth [Rajan et al., (1987)]. The inversion algorithm involves solving an ill-posed problem, with regularization used to stabilize the solution, resulting in a smoothed version of the true sound speed profile. To simultaneously estimate water column and seabed properties, qualitative regularization is used to resolve the discontinuity in the sound speed profile at the seafloor and approximate equality constraints are used to constrain the solution in portions of the water column for which the data alone are insufficient. The primary advantage of simultaneously inverting for water column and sediment sound speed profiles is that poor knowledge of a priori information about water column is not aliased into the solution for the seabed. [Work supported by NDSEG and ONR.]