Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: March 22, 2011
Publication Date: April 27, 2011
Citation: Zhao, T., Jackson, T.J., Bindlish, R., Cosh, M.H. 2011. Validation of soil moisture ocean salinity (SMOS) satellite soil moisture products [abstract]. Abs. 62. BARC Poster Day. Technical Abstract: The surface soil moisture state controls the partitioning of precipitation into infiltration and runoff. High-resolution observations of soil moisture will lead to improved flood forecasts, especially for intermediate to large watersheds where most flood damage occurs. Soil moisture is also key in determining plant productivity and yield. The use of validated soil moisture estimates in agriculture prediction models will lead to significant improvements in operational crop productivity. The European Space Agency Soil Moisture Ocean Salinity (SMOS) satellite was launched in November 2009 to obtain passive microwave measurements at a wavelength that is optimal for soil moisture retrieval. It uses the first-ever, space-borne, two-dimensional interferometric radiometer operating at 1.4 GHz. L-band observations provide enhanced sensitivity to surface soil moisture as compared to higher frequency satellite radiometers. SMOS footprints have a spatial resolution of 40 km. We are currently in validation phase of this satellite project. Conventional ground-based measurements of soil moisture are made at a point whereas satellite sensors provide an integrated value for a much larger spatial extent (~40 km for SMOS). This makes the validation of soil moisture challenging. Our efforts focus on the use of a set of dense in situ soil moisture observing networks distributed across the US. These sites approximate the size of a SMOS footprint, with relatively uniform surface conditions. Measurement data have been calibrated and verified through field campaigns and applied to validating other satellite products. In the current study, one-year of SMOS soil moisture products are compared with the in situ data. It was found that SMOS products are very close to meeting the satellite project goal of a root mean square error less than 0.04 m3/m3. The analysis of individual sites revealed important insights on the impact of vegetation and related seasonal effects on the retrieval. These results will contribute to refinements in the algorithms and the wider acceptance of the data for applications.