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

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

R. A. Stephen

Woods Hole Oceanogr. Inst., Woods Hole, MA 02543

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.]