Potential of Sentinel-1 for high-resolution soil moisture monitoring

Soil moisture is a crucial variable for a large variety of applications with different requirements on the spatial and temporal resolution of the observations. Coarse-scale instruments can provide data operationally with a nearly-daily global coverage at a spatial resolution of several hundreds of square kilometers, whereas SAR instruments provide a spatial resolution of less than one hectare to about one square kilometer but with a revisit time varying from several days to several months. This study uses coarse-scale MetOp ASCAT data and higher resolution Envisat ASAR data taken in the GM mode and the WS mode together with in-situ measurements to demonstrate (i) the potential of Sentinel-1 to capture very local soil moisture variations and (ii) the expected impact of the significantly improved radiometric accuracy of Sentinel-1 compared to existing soil moisture missions.