The estimation of wide-angle bottom loss by a normal incident acoustic pulse

The grazing-angle characteristics of bottom loss can be computed from the ocean bottom structure (i.e., the sound-speed, density and attenuation profiles). We present a method for estimating the density and attenuation coefficient profiles of the bottom from the reflected signal of normal incident pulse: this method assumes that the sound-speed profile is known. The density and attenuation coefficients in each layer are estimated from the amplitude of frequency response of returning pulse using a weighted least-squares-method. Then, the wide-angle bottom loss is computed from the estimated bottom structure. To show the capability of this method, we present a numerical simulation which is based on a synthetic reflected signal of a hypothetical bottom structure with additive noise. The influence of an estimated error on sound propagation in the ocean is examined.