Smos soil moisture validation: Status at the Upper Danube cal/val site eight months after launch

The validation of SMOS L2 soil moisture data requires the maintenance of long-term soil moisture monitoring sites. One such site is the Upper Danube SMOS validation site situated in Southern Germany with a size of 77000 km². Since 2007, the University of Munich routinely collects in situ soil moisture data within the test site in preparation for the SMOS validation. An operational framework has been built up to compare SMOS soil moisture products against in situ measurements, land surface model simulations and ancillary satellite data. An airborne SMOS validation campaign has been conducted between spring and early summer 2010 in the Upper Danube catchment. Two airborne L-band radiometers (EMIRAD, HUT-2D) were flown during a multi-week period, covering parts of a SMOS pixel to validate the satellite data. Comprehensive ground data was collected during this campaign. The paper will give an overview about the existing data sets, the developed infrastructure and ongoing activities in the Upper Danube SMOS validation site. A first evaluation of SMOS satellite data, eight months after launch, will be presented.