Retrieving of Surface Roughness for Agricultural Soil Surfaces with Asar-envisat Data

The objective of this paper is to improve the understanding of surface roughness description based on experimental campaigns involving the ASARENVISAT (Advanced Synthetic Aperture Radar) radar. Two presentations of surface correlation function are proposed in this study: ( ) ( ) ( ) α ρ l x e s x / 2 − = and ( ) ( )[ ] ( ) ) / ( 2 / l x b a l x e s x + − = ρ . The experimental database contains a large number of experimental campaigns with ground truth (roughness, moisture) and satellite ASAR-ENVISAT measurements with different meteorological and tillage conditions. It was shown that α parameter is highly dependent on the rms height and the history of the agricultural tillage. A relationship is proposed between the rms height and α parameter. Using α function, comparisons between radar measurements for high incidence angles (37.5°, 40°, 43° and 44.5°) and numerical backscattering model simulations for different test fields and different dates, are realised. For high and medium moistures, results show a good agreement for soil surfaces with a rms height lower than 2 cm.