Mapping surface soil moisture over the Gourma mesoscale site (Mali) by using ENVISAT ASAR data
- 1CESBIO (Centre d'Etudes Spatiales de la Biosphère, UMR 5126, UPS-CNRS-CNES-IRD), 18 avenue Edouard Belin, 31401 Toulouse cedex 9, France
- 2GET (Géosciences Environnement Toulouse, UMR 5563 CNRS-UPS-IRD) Observatoire Midi-Pyrénées 14 avenue Edouard Belin, 31400 Toulouse, France
- 3ECMWF (European Centre for Medium-Range Forecasts), Reading, Berkshire, UK
- 4Laboratoire des Géomatériaux, Université Marne La Vallée, Institut Francilien des Sciences Appliquées, 5 bd Descartes, 77454 Marne la Vallée Cedex 2, France
Abstract. The potentialities of ENVISAT ASAR (Advanced Synthetic Aperture Radar) multi-angle data for mapping surface soil moisture (SSM) in Sahelian rangelands are investigated at medium scale (30 000 km2). The Wide Swath data are selected to take advantage of their high temporal repetitivity (about 8 days at the considered scale) associated to a moderate spatial resolution (150 m). In the continuity of previous studies conducted at a local scale in the same region, SSM maps are here processed over the whole AMMA Gourma mesoscale site at 1 km resolution scale. Overall, the generated maps are found to be in good agreement with field data, EPSAT-SG (Estimation des Pluies par SATellite – Second Generation) rainfall estimates and ERS (European Remote Sensing) Wind Scatterometer (WSC) SSM products. The present study shows that the spatial pattern of SSM can be realistically estimated at a kilometric scale. The resulting SSM maps are expected to provide valuable information for initialisation of land surface models and the estimation of the spatial distribution of radiative fluxes. Particularly, SSM maps could help to desaggregate low-resolution products such as those derived from WSC data.