RFI and SMOS: Preparatory campaigns and first observations from space

In support of the ESA Soil Moisture and Ocean Salinity (SMOS) mission, a number of campaigns, including airborne L-band radiometer measurements, have been carried out. The radiometer used in this context is fully polarimetric and has built-in Radio Frequency Interference (RFI) detection capabilities. This paper introduces the radiometer system and how it detects RFI using the kurtosis method. Analyses have shown that the kurtosis method generally detects RFI in an efficient manner even though it has its shortcomings. Hence, other detection methods have been investigated as well. In particular, inspection of the 3rd and 4th Stokes parameters shows promising results - possibly as a complement to the kurtosis method. The kurtosis method, however, cannot be used with SMOS data. Since SMOS will be operated in a polarimetric mode at least for periods of its lifetime, 3rd and 4th Stokes parameter inspection has been carried out on a recent, fully polarimetric SMOS data set.