Radar backscatter characteristics of a desert surface

Satellite radar altimeter measurements have shown spatial and temporal variations in the backscattered signal from desert surfaces. In order to understand these variations we have carried out extensive in situ measurements for the validation of a compilation of existing backscatter models. The model predictions are in excellent agreement with ground- and satellite-based measurements of the radar backscatter coefficient, and show that the altimeter backscatter measurements are strongly affected by variations in soil moisture following rainfall and by the presence of dew on the surface. Regional, but time-invariant, differences in backscatter are attributed to variations in surface topography.