Model and data comparison for bottom backscattering

Abstract

Acoustic and geoacoustic data from two sites have been compared with a model [D. R. Jackson et al., J. Acoust. Soc. Am. 79, 1410–1422 (1986)] for bottom backscattering strength at high frequencies. At one site, the sediment was a fine sand with prominent, directional ripples. At the other site, the sediment was a mixture of clay, sand, and shell. The geoacoustic data were used to obtain values for the following model input parameters: sediment sound speed, sediment mass density, and the power spectrum for bottom microrelief. The model also requires a sediment volume scattering parameter, which was obtained by fitting backscattering data. The model generally gave good descriptions of the level and grazing angle dependence of the backscattering strength, and the results indicate that roughness scattering was dominant at the sandy site, while sediment volume scattering was dominant at the sandy site. At the sandy site, the microrelief spectrum showed appreciable anisotropy and an unusually rapid falloff with...