Abstract
Motivated by interesting anomalies observed in recent transmission experiments across the Kermit Seamount in the Pacific, a numerically efficient three-dimensional (3D) propagation and scattering model has been developed based on 3D coupled mode theory for axisymmetric bathymetry. The 3D coupled mode approach applied here is based on the same spectral representation of the field as earlier models presented by Athanassoulis and Propathopoulous [J. Acoust. Soc. Am. 100 (1996)] and Tarudakis [J. Comp. Acoust. 4 (1996)]. However, the earlier formulations were severely limited in terms of frequency, size, and geometry of the seamount, the seabed composition, and the distance of the source from the seamount, and are totally inadequate for modeling the Kermit experiment. By introducing a number of changes in the numerical formulation and using a standard normal mode model (CSNAP) for determining the fundamental modal solutions and coupling coefficients, orders of magnitude improvement in efficiency and fidelity have been achieved, allowing for realistic propagation and scattering scenarios to be modeled, including effects of seamount roughness, realistic sedimentary structure. By comparing to traditional n-by-2D coupled mode results, the model is used to demonstrate and investigate the surprisingly strong significance of 3D effects associated with propagation across oceanic seamounts such as Kermit, reaching up to the depth of the SOFAR channel. [Work supported by the US Office of Naval Research, Code 321OA.]
Published Version
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