Extraction of soil moisture information from SAR satellite data

Relating to the global climate change prediction, hydrologists are interested in large-scale hydrological processes, particularly in evapotranspiration processes as an interaction between the land surface and the atmosphere. Soil moisture is an important factor controlling the evapotranspiration process. SAR data of E ERS-1 and J ERS-1 are expected to provide large-scale soil moisture information which can be incorporated into a macro-hydrological model. However, radar backscatter is sensitive not only to soil moisture but also to surface conditions and soil characteristics. The authors carry out simultaneous verification experiments at five sites with different surface-soil conditions to establish the relationship between ERS-1 radar backscatter and soil moisture. Experiments include direct sampling of surface soil, measurement of backscatter using a C-band scatterometer mounted on an automobile and field dielectric measurements using potable C- and L-band dielectric probes. Some preliminary results are reported