GPS radio occultation with CHAMP: Comparison of inversion results from GFZ

Summary. A major application of the CHAMP occultation data is the prepara-tion of processing systems for future occultation missions. The University of Graz (IGAM) uses data and analysis results to prepare for the ACE+ multi-satellite oc-cultation mission, which is currently foreseen to be launched in 2008. We compare vertical profiles of refractivity, derived by GFZ and IGAM, with ECMWF data (European Centre for Medium-Range Weather Forecasts) and discuss the devia-tions. Good agreement is observed in the upper troposphere and stratosphere. The magnitude of the observed refractivity bias in the lower troposphere depends sig-nificantly on the quality control criterion. The bias can be nearly eliminated by the application of the Full Spectrum Inversion analysis method down to ∼1 km above the Earth’s surface