Comparison of Different Implementation Options for Density Discontinuity in Split Step Fourier Parabolic Equation Models

摘要

This paper studies alternate ways to model density discontinuity in split-step Fourier parabolic equation models. The Monterey-Miami Parabolic Equation model is used to implement an alternative to the effective index term in the smoothing function and a split-step Fourier/Finite Difference hybrid technique. The model is shown to converge to a stable solution that is slightly lower than the benchmark solution. A range step size of approximately one wavelength is shown to provide the closest approximation to the benchmark solution. Acceptable solutions are obtained with large depth grid sizes for the alternate smoothing function. Smaller depth grid sizes are necessary for accurate solutions when using the hybrid implementation technique. The effect of reference sound speed is shown to minimize the phase error present when the models are used in the presence of a strong density discontinuity.