Mapping surface soil moisture over the Gourma mesoscale site (Mali) by using ENVISAT ASAR data

摘要

The potentialities of ENVISAT ASAR (Advanced Synthetic Aperture Radar)multi-angle data for mapping surface soil moisture (SSM) in Sahelian rangelandsare investigated at medium scale (30 000 km2). The Wide Swath data areselected to take advantage of their high temporal repetitivity (about 8 daysat the considered scale) associated to a moderate spatial resolution (150 m).In the continuity of previous studies conducted at a local scale in the sameregion, SSM maps are here processed over the whole AMMA Gourma mesoscale siteat 1 km resolution scale. Overall, the generated maps are found to be in goodagreement with field data, EPSAT-SG (Estimation des Pluies par SATellite –Second Generation) rainfall estimates and ERS (European Remote Sensing) WindScatterometer (WSC) SSM products. The present study shows that the spatialpattern of SSM can be realistically estimated at a kilometric scale. Theresulting SSM maps are expected to provide valuable information forinitialisation of land surface models and the estimation of the spatialdistribution of radiative fluxes. Particularly, SSM maps could help todesaggregate low-resolution products such as those derived from WSC data.