New methodology for soil surface moisture estimation and its application to ENVISAT-ASAR multi-incidence data inversion

A method of normalisation of all radar data acquired at different incidence angles is first described. Secondly, the effects of roughness and soil texture on the linear relationship between moisture and radar signals are discussed. Finally, the proposed methodology to reduce these effects is developed. The validation of our approach is based on eight experimental campaigns with different ASAR incidence angles, and different surface moisture conditions. The processed radar signal shows a linear relationship with the mean measured soil surface moisture, with very high correlation (R2 = 0.97) and a slope of 0.28. These results illustrate the high potential of the developed approach and ENVISAT-ASAR to monitor surface moisture.