Abstract:

Wave-number integration (WI) approaches directly implement the ``exact'' spectral formulation for the seismoacoustic field in ocean waveguides. Therefore, these modeling approaches are inherently limited to range-independent, or horizontally stratified, environments. However, WI possesses a number of unique seismic capabilities, and various wave-field coupling approaches have recently been combined with WI to extend its applicability to two-way, seismoacoustic propagation in strongly range-dependent environments. These hybrid modeling approaches use a stepwize discretization of the environment similar to the one used in coupled-mode models. The spectral super-element approach [J. T. Goh and H. Schmidt, J. Acoust. Soc. Am. 100, 1409--1420 (1996)] then uses a Galerkin boundary-element formulation for the coupling between the range-independent sectors (super elements), while the virtual source approach [H. Schmidt, Proc. SWAC-97, Beijing (Apr. 1997)] uses an approximate, but highly efficient, local solution to the coupling problem. The performance of these new approaches has been demonstrated using a new class of two-way seismoacoustic benchmark problems with both weak and strong range dependence. Here, the new modeling approaches will be described, and their unique seismoacoustic capabilities will be discussed and illustrated by application to, e.g., the deep-ocean waveguide coupling of near-shore tomography sources, and analysis of potential seismoacoustic coupling mechanisms for oceanic T phases. [Work supported in part by the Office of Naval Research.]