Spatial and Temporal Distribution of Soil Moisture Estimation from ENVISAT ASAR Wide Swath Data for Grassland in Ireland

Soil moisture (SM) is an important parameter for hydrological research. Estimation of SM over large areas using remote sensing data is now possible. Using ENVISAT data together with in situ measured SM data, we developed a model for simulating soil moisture dynamics of a 1200 km grassland catchment in Ireland. We then compare the modeled output with SM from the physically based hydrological model GEOTOP. Some algorithms exist to derive surface soil moisture estimates from remote sensing data. For the ASAR data from the ERS mission, an existing method has been widely used, and was shown to be reliable. The method simulates the relationship between the dielectric constant and the backscattering coefficient for different land cover types, and the relationship can be described as