Soil Moisture Retrieval from AMSR-E: A Statewide Application and Verification Using Observations and the SWAT Model

Soil moisture is one of the key variables in numerous environmental and risk assessment studies. Surface soil moisture information obtained through microwave remote sensing technology is useful in agriculture, hydrology and meteorology and can be used to characterize the spatial and temporal variability of soil moisture, especially at large scales. Since 2002 the Advance Microwave Scanning Radiometer for the Earth observing system (AMSR-E) onboard the NASA EOS AQUA satellite has been used for accurate estimation of Surface Soil Moisture (SSM) content. In AMSR-E, microwaves detect soil moisture variability based on the effects moisture has on the dielectric constant and hence emissivity of the soil. Surface roughness and vegetation can affect the sensitivity of soil moisture measurements. The goal of this study is to compare the inter-annual variability of AMSR-E derived soil moisture for three growing seasons between 2002 and 2005 with observed soil moisture collected from fourteen sites across the state of Nebraska. We derive cumulative distribution functions for AMSR-E, observations and model estimates and cross-validate the results. Soil Water Assessment Tool (SWAT) will be used for the model simulation. We plan to extend this approach to understand the spatial variability of soil moisture characteristics in the context of predicting agricultural drought over a large region.