Modeling of 3D effects in shallow water sound propagation using PE approximation

Shallow water environment (shelf zone of the ocean) is often characterized by remarkable horizontal variations of parameters (bathymetry, sound speed profile, bottom properties etc.), initiating redistribution of the sound field in horizontal plane depending on mode number and frequency (the so called three dimensional or 3D effects). In this paper variations of waveguide parameters having different scales of variability in different directions are considered: coastal slope, nonlinear internal wave, which can be specified as horizontal stratification. Based on the approach of vertical modes and the parabolic equation (PE) in horizontal plane, 3D effects in propagation of sound signals in the presence of horizontal stratification are considered: variations of spectra of broadband signal, propagating from the source to receiver, interference between direct and reflected signals in multipath area of horizontal plane for different mode numbers and frequency, compression and decompression of signals.