A simple algorithm 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 an 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 sufficiently sensitive to near surface soil moisture. However, the spatial resolution of a typical satellite mounted L band radiometer is of the order of 10´s of kilometers which is not sufficient to serve the science needs of 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 hold the promise of making global soil moisture observations at much finer scale available. The HYDROS instrument is proposed to have an L band radiometer and L band radar onboard. The passive instrument has spatial resolution of the order of tens of kilometers and operates along with the active instrument that takes observations at a resolution of tens of meters. This paper presents a simple approach for disaggregation of coarser resolution radiometer estimates of soil moisture using higher resolution radar backscatter measurements. The algorithm has been applied to a coincident PALS radar/radiometer and AIRSAR dataset acquired during the SMEX02 campaign