Downscaling of SMOS derived soil moisture and validation with ground truth data

On Nov 02, 2009, European Space Agency (ESA) launched Soil Moisture and Ocean Salinity (SMOS) mission to monitor surface soil moisture and sea surface salinity using natural L-Band microwave emission. As the operating frequency of SMOS is 1.4 GHz, consequently, in spite of its high temporal resolution (~3 days), has low spatial resolution of ~ 40 km. In the present paper, downscaling of SMOS derived low resolution soil moisture is done by synergistically combining it with high resolution optical/IR data from MODIS over a test site in Gujarat, India and validated the same against ground truth soil moisture data at 1 km spatial resolution. In the validation, it is observed that the difference between downscaled soil moisture (%) and ground truth soil moisture (%) is below 4.12 % for 60% of total datasets and for 90% of total datasets the difference is below 11%.