Broadband modeling of sound propagation in shallow water with an irregular elastic bottom

Abstract

The purpose of this work is to study the propagation of broadband sound pulses in shallow water environments. It is essential for an underwater pulse propagation model to handle bottom interaction, range-dependence, and wide-angle propagation in shallow water. Therefore, a comparatively realistic model that consists of a fluid overlying an irregular elastic bottom is treated, where the effects of shear wave are included. The range-dependent seismo-acoustics problem in frequency-domain is solved by a parabolic equation model. Fourier synthesis of frequency-domain solutions is implemented to model the received time series of a broadband sound propagation. And parallel programming is tried to improve the computational efficiency. Dispersion characteristics are exhibited by multiple mode arrivals during the propagation, including the dispersion of normal modes and mode 0 (the Scholte wave). The dispersion analysis of normal modes and the Scholte wave are demonstrated under different types of elastic bottoms. Energy converting between trapped modes and leaky modes due to slope of bottom is also analyzed.