A plane wave reflection loss model based on numerical integration

Abstract

A method is developed for computation of the complex plane‐wave reflection coefficient for a class of geoacoustic models of the ocean bottom, consisting of an arbitarary number of inhomogeneous (fluid) sediment layers overlying a a semi‐infinite homogeneous solid substrate (basement). Within the sediment layers the density, sound speed, and attenuation are permitted to vary arbitrarily with depth. An appropriate formulation of the problem permits the reflection coefficient to be constructed using the results obtained from the direct numerical integration of the depth separated wave equation. The entire computation is thus reduced to that of an initial value problem to which established methods can be applied. The Runge–Kutta method which was chosen permits user selected local error tolerances. Extensive application of the resulting computer code has shown that for a wide class of physically reasonable models global error is bounded, and accuracy far in excess of the minimum required is easily obtained. Requirements imposed on computer word size and available core are modest, and the model can be implemented on any modern general purpose computer and perhaps on a minicomputer.