Soil moisture at watershed scale: Remote sensing techniques

•Two distinct microwave soil moisture disaggregation approaches have been used.•The disaggregated soil moisture in both of these approaches has been compared to in situ observations.•The accuracy of the soil moisture disaggregation methods varies through years and seasons. Soil moisture at high spatial resolution is required for various land processes related studies. However, currently the resolution of passive microwave retrieved soil moisture is low – around 25km. To solve this problem, a soil moisture disaggregation algorithm based on thermal inertia relationship between daily temperature change and average soil moisture modulated by vegetation conditions has been formulated. This algorithm was applied to the AMSR-E (Advanced Microwave Scanning Radiometer – Earth Observing System) as well as SMOS (Soil Moisture and Ocean Salinity satellite) to produce the 1km downscaled soil moisture over the Little Washita Watershed in Oklahoma for the growing season in 2010 and 2011.The disaggregated soil moisture has been compared to in situ observations. The results of this approach are very encouraging.