Modeling of shallow water reverberation data

Abstract

A broadband model of seabed reverberation in a shallow water waveguide is used to analyze data measured in the Area Characterization Test I (ACT I). Given a source spectrum, a mean geoacoustic profile for the waveguide, and statistics characterizing the scattering sources (including fluctuations in seabed sound speed and density as well as seabed interface roughness) the model simulates time series measured in a monostatic geometry. It accomplishes this by solving the integral form of the Helmholtz equation in a random medium in the Born (or single scattering) approximation using the ORCA normal mode model to compute the unperturbed Green’s functions. Statistics of the scattering sources are inferred from comparisons between modeled time series and experimental data. Also, the effects of uncertainties in the source spectrum are considered, and the validity of the Born approximation in this context is discussed. [Work supported by ONR.]