Low Grazing Angle Terrain Backscattering Coefficient Generator

A near-horizon probabilistic terrain backscatter coefficient ( generator is introduced, combining modified sea-state curves with Weibull-type probability density functions. A total of nine terrain type classifications (soils and rocks, trees, grasses, shrubs, short vegetation, roads, urban areas, dry snow, and wet snow) are supported, for seven radar bands (L, S, C, X, Ku, Ka, and W), and both linear (HH, VV) and cross (HV, VH) polarizations. The Weibull functions are based on measured ?? and match the published data. The functions also provide a probabilistic nature to the generator. Modified sea state curves are used in place of the Weibull functions for near-horizon incidence angles (75o - 90o) due to the dearth of measured data at this range. The sea state approach is based on the theory that for ??, similar surface roughness of two different terrain types results in similar ?? curve shapes. Generator testing and validation used available measured ??o at 85o for three terrain types. The testing did not reject the modified sea curve usage and allowed system implementation for the remaining terrain types.