### ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

## 5aUW11. Modeling sea surface scattering with a finite difference method.

**R. A. Stephen
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*Woods Hole Oceanogr. Inst., Woods Hole, MA 02543
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A numerical scattering chamber based on the finite difference solution of
the two-way elastic wave equation is applied to the sea surface scattering
problem. For a reference model, the method gives excellent agreement in
amplitude and phase with the solution obtained by an integral equation method
[Eric Thorsos, personal communications]. This problem demonstrates a number of
issues in numerical modeling of wave scattering: (1) the spreading of Gaussian
beams (even in homogeneous media) has implications for (i) defining the surface
footprint or scattering area and (ii) for generating approximate Gaussian beams
by tapered vertical arrays; (b) the treatment of a rough, free, fluid surface
in a Cartesian grid scheme; (c) solving continuous wave (cw) problems in the
time domain; (d) diffraction of waves from roughness elements with scale
lengths on the order of a wavelength; (e) multiple scattering effects between
roughness elements; and (f) omni-directional scattering including low angle
backscatter. [Work supported by Office of Naval Research.]