Small-slope predictions of microwave backscatter from the sea surface

The small-slope approximation is applied to the prediction of microwave sea-surface backscatter. Numerical results are obtained assuming a non-directional surface wavenumber spectrum and compared with azimuthally averaged C- and Ku-band radar backscattering data. For vertical polarization, the predictions and measurements agree to within 3 dB at incidence angles of interest for remote sensing. Small-slope predictions of azimuthal scattering asymmetry do not agree as well with measurements. These predictions are found to be sufficiently dependent on the assumed wave directionality that they may be used to improve existing directional wave spectral models.