Abstract:
An efficient normal mode solution for range-dependent sound propagation is developed for application to the shallow water waveguide. The approximate method, coupled perturbed modes, combines conventional discrete coupled mode theory and perturbation theory. Analytic expressions for the change in mode shapes, change in wavenumbers, and change in mode coefficients are derived for a given small change in either a sound speed profile or a sound speed profile and a bathymetry-dependent density profile. Attention is given to problems involving internal solitary waves and penetrable wedges.