RADAR BACKSCATTER CHARACTERISTICS OF A DESERT SURFACE

Satellite radar altimeter measurements have shown spn tial and tempora l variations in the backscattered signal from desert surfaces. In orde r to understand these variations we have carried out extensive in situ measurements for the validation of a compilation of existing backscat ter models. The model predictions are in excellent agreement with grou nd- and satellite-based measurements of the radar backscatter coeffici ent, 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, differe nces in backscatter are attributed to variations in surface topography .