Abstract:

A newly developed pseudospectral numerical model is used to study pulse propagation through continental-shelf internal waves. A time-domain mode coupling analysis is performed on plane-wave pulses propagating through a simple internal solitary wave (ISW) described by downward undulation of a thermocline having the shape of hyperbolic secant. Initial acoustic fields made up of eight-cycle Hanning-weighted sine waves with 224- and 400-Hz center frequencies (vertically shaded by desired acoustic mode shapes) are used. Two-dimensional and three-dimensional numerical results were compared to investigate the validity of two-dimensional techniques in the case of nonparallel acoustic-ISW alignment. Similar to the results of Preisig and Duda [IEEE J. Oceanic Eng. 22(2) (1997)], it has been observed that the horizontal refraction and azimuthal scattering seem to be minor for up to 65-deg oblique incidence angle. Results of two-dimensional propagation and mode-coupling analysis for the ISW packets measured during the SWARM95 experiment are also discussed. [Work supported by ONR.]