Comparing data of two airborne L-band radiometers with different spatial resolution over a heterogeneous land surface

This paper describes a first attempt of comparing data of the two airborne L-band radiometers EMIRAD and HUT-2D over land surface. While HUT-2D is an imaging system with a high spatial resolution, EMIRAD delivers data averaged over a relatively large footprint but can be considered to be more stable. The Upper Danube catchment, located mostly in Southern Germany, is one of two major test sites in Europe for the calibration and validation activities for the Soil Moisture and Ocean Salinity (SMOS) mission launched by the European Space Agency (ESA). For the study presented in this paper, the radiometric measurements collected during the SMOS Validation Rehearsal Campaign 2008 in the Upper Danube catchment are used. The results suggest that differences between the measurements are mainly controlled by temperature effects and can be limited by implementing a temperature correction in the processing of HUT-2D data.