Accession Number : ADA292025

Title :   Modeling Backscattering from a Rough Seafloor with Sediment Inhomogeneities.

Descriptive Note : Final rept.,

Corporate Author : NAVAL RESEARCH LAB STENNIS SPACE CENTER MS

Personal Author(s) : Novarini, Jorge C. ; Caruthers, Jerald W.

PDF Url : ADA292025

Report Date : 27 FEB 1995

Pagination or Media Count : 25

Abstract : Current models used to predict the backscattering strength of the ocean floor are either very involved, requiring geoacoustic parameters usually unavailable for the site in practical applications, or overly simplistic, relying mainly on empirical terms such as Lambert's law. In any case, solutions are very approximate and the problem is still far from being solved. In this work, a model is presented that avoids empirical functional forms, yet requires only a few physical parameters to describe the surficial sediments, often tabulated for typical sediments. The aim of the work is to develop a simple algorithm for operational prediction of bottom reverberation with only one free parameter, i.e., the volume scattering coefficient. The algorithm combines a two-scale surface scattering model with scattered contributions originating from inhomogeneities within the sediments, taking into consideration the rough interface. No specific mechanism is assumed for scattering at the volume inhomogeneities; however, the inhomogeneities are assumed to be uniform and isotropic. The volume scattering coefficient, combined with the bottom attenuation and density and referenced to the surface, plays a role similar to the Lambert's constant in empirical models. The model is exercised on a variety of published datasets for low and moderately high frequency. In general, the model performs very well for both fast and slow sediments, showing a definite improvement over Lambert's law. (AN)

Descriptors :   *BACKSCATTERING, *UNDERWATER ACOUSTICS, *OCEAN BOTTOM, MATHEMATICAL MODELS, ALGORITHMS, PARAMETERS, SURFACE ROUGHNESS, OCEANOGRAPHIC DATA, SHALLOW WATER, GEOACOUSTICS, MATHEMATICAL PREDICTION, HETEROGENEITY, ACOUSTIC ATTENUATION, ACOUSTIC SCATTERING, REVERBERATION, SONAR, SEDIMENTS, BRAGG SCATTERING.

Subject Categories : Acoustics
      Physical and Dynamic Oceanography

Distribution Statement : APPROVED FOR PUBLIC RELEASE