A Simple Method for Spatial Disaggregation of Radiometer Derived Soil Moisture using Higher Resolution Radar Observations

The SMEX02 experiments held in June–July 2002, at Iowa demonstrated the potential of the L band radiometer (PALS) in estimation of near surface soil moisture under dense vegetation canopy conditions. The L band radar was also shown to be sensitive to near surface soil moisture. However, the spatial resolution of a typical satellite L band radiometer is of the order of tens of kilometers, which is not sufficient to serve the full range of science needs for land surface hydrology and weather modeling applications. Disaggregation schemes for deriving sub pixel estimates of soil moisture from radiometer data using higher resolution radar observations may provide the means for making available global soil moisture observations at much finer scale. This paper presents a simple approach for disaggregation of coarser resolution radiometer estimates of soil moisture using higher resolution radar backscatter and vegetation water content measurements. The algorithm has been applied to coincident PALS radiometer and Airsar datasets of 400 m and 30 m spatial resolutions respectively acquired during the SMEX02 campaign. PALS radiometer estimates of soil moisture at a 400 m resolution have been disaggregated to 100 m resolution.