Integrating the energy flux method of shallow-water reverberation with physics-based seabed scattering models.

Abstract

The energy flux (angular spectrum) method for shallow-water (SW) reverberation was first presented 3 decades ago in archived Chinese journals. These included closed form expressions for reverberation in SW with a down refraction or isovelocity profile. [Zhou, Acta Acust. 5, 86–99 (1980); Chin. J. Acoust. 1, 54–63 (1982)]. More papers on SW reverberation using this method have recently been published in JASA and IEEE JOE. However, most of these papers are based on semiempirical seabed scattering models, which do not have a physical basis. In the past 30 years, one of the major accomplishments in ocean acoustics is the improvement in our understanding of seabed scattering, resulting from a significant effort of both at-sea measurement and theoretical modeling. [Jackson and Richardson, High-Frequency Seafloor Acoustics, (2007)]. Benefiting from this accomplishment, this paper integrates the energy flux model of SW reverberation with the physics-based seabed scattering models in the angular domain. This integration directly and intuitively results in a general expression for SW reverberation in terms of seabed physical/scattering parameters, and this expression is almost identical with the expression derived from the boundary perturbation method. The results may be used to estimate the bottom roughness or sediment inhomogeneity from SW reverberation measurements.[Work supported by the ONR and CAS].