REMOTE-SENSING OF BARE SURFACE SOIL-MOISTURE USING EMAC ESAR DATA/

In this paper we present first results of bare surface soil moisture r etrieval using data from the European Multisensor Airborne Campaign/Ex perimental Synthetic Aperture Radar (EMAC/ESAR) collected on 9 April 1 994 in the Zwalm catchment, Belgium. Data from EMAC Reflective Optics System Imaging Spectrometer (ROSIS) collected on 12 July 1994 over the same catchment were used to develop land use maps. Concurrent to the EMAC/ESAR overflights field data were collected in two subcatchments o f the Zwalm catchment. The paper first presents the data processing pr ocedures used for the radar images. Then we apply a theoretical backsc attering model to investigate the sensitivity of EMAC/ESAR backscatter ing coefficients to surface parameters (topography, surface roughness, vegetation and soil moisture). By comparing the predicted backscatter ing coefficients to the observed ones, we can conclude that classical measurement techniques for surface roughness parameters in remote sens ing campaigns are not accurate enough for retrieving soil moisture usi ng theoretical models. A method based on simultaneous retrieval of sur face roughness parameters and soil moisture using multiple ESAR measur ements is hence proposed. Promising results for retrieved soil moistur e confirm the validity of the proposed method.