A parabolic equation model for scattering in the ocean

Abstract

The small-angle-of-propagation limit and the method of matched asymptotics are applied to derive an efficient model for solving realistic underwater acoustics problems involving both propagation and scattering from a submerged object. The propagation and scattering aspects of the waveguide scattering problem are decoupled by approximating the waveguide Green’s function on the surface of the scatterer. For low frequencies, the small-angle limit also allows one to approximate the incident field with a horizontally propagating plane wave and the scattered field with an azimuthally specular point-source field. With these approximations, scattering calculations can be performed efficiently in the time domain. Calculations involving the three-dimensional parabolic equation and the time-domain parabolic equation are presented.