Transport theory for range dependent environments.

Abstract

Transport theory has been developed for modeling shallow water propagation at mid frequencies (1–10 kHz) where forward scattering from a rough sea surface is taken into account in a computationally efficient manner. The method is based on a decomposition of the field in terms of unperturbed modes, and forward scattering at the sea surface leads to mode coupling that is treated with perturbation theory. Aside from the rough sea surface, the environment has previously been taken as range independent. In order to extend the applicability of this approach, range dependence is now considered in the form of a varying bottom depth. The conditions under which adiabatic modes can be incorporated into transport theory to account for slow deterministic variation in the waveguide depth have been investigated and will be described. Rough surface PE simulations are used to provide ground truth for the transport theory method. [Work supported by ONR Ocean Acoustics.]