APPLICATION OF ITERATIVE MOMENT-METHOD SOLUTIONS TO OCEAN SURFACE RADAR SCATTERING

Numerical methods such as the banded matrix iterative approach (BMIA) represent a major advance in the direct numerical simulation of rough surface-wave scattering, This paper considers the application of itera tive methods such as the BMIA to ocean-radar scattering, It is shown t hat for typical microwave radar frequencies and sea-surface roughness, the BMIA is actually of limited use, A more general iterative solutio n based on a multigrid decomposition and the generalized conjugate res idual (GCR) method, is thus developed. The multigrid approach is ideal ly suited to the broad-band ocean surface, as it solves the scattering problem on a sequence of grids, each corresponding to a different ran ge of spatial frequencies or length scales, This approach is applied h ere to several sea scattering problems, including very low grazing ang les and both horizontal and vertical polarization, Good agreement is o btained with perturbation theory in the appropriate limits and several qualitative characteristics of radar backscatter data are reproduced.