Gaussian beam algorithm for bottom reflection and head waves due to extended aperture sources

Abstract

Gaussian beams furnish a useful algorithm for high-frequency sound propagation in complex environments but in their paraxial implementation, they are flawed by spectral defects that obscure certain wave phenomena. Critical reflection and head wave generation due to a fast bottom belong in this category. In a separate study, methods for “fleshing out” the deficient spectrum for the prototype structure of a homogeneous ocean and a homogeneous fluid bottom, have been explored with excitation due to a line source [[X. J. Gan et al., 2nd IMACS Symposium, Princeton University (March 1989)]. In the presentation here, these methods of excitation from a continuously distributed extended aperture source and from an array of line sources have been applied. In the Gaussian beam modeling, not only are the ad hoc discretization that involves arbitrary parameters employed but the self-consistent Gabor phase space stacking are also employed. It is found that distributed sources deemphasize the above-noted spectral defects but do not remove them entirely. [Work supported by ONR.]