Low-frequency, bottom-interacting pulse propagation in range-dependent oceans

An asymptotic-numerical model for low-frequency, bottom-interfacing pulse propagation in the ocean is derived. This model, referred to as the progressive wave equation (PWE), works in the time domain using an approach analogous to the parabolic equation method that is commonly used in the frequency domain. The mode handles depth and range variations in the speed of sound, density, and attenuation. The attenuation is assumed to depend linearly on frequency in the sediment. A numerical solution for the PWE was derived, and the accuracy of the asymptotics, numerics, and starting field was demonstrated with a benchmark