It was shown that accurate zonal mean, seasonal mean climatologies between km and 30 km altitude can be obtained based on Radio Occultation (RO) profiles. The assimilation of RO data at ECMWF (European Centre for Medium-Range Weather Forecasts) considerably improved operational analyses in regions where the data coverage and/or the vertical resolution and accuracy of RO data is superior to traditional data sources (e.g., in polar regions and at altitudes up to ~35 km). We analyzed the consistency of seasonal climatologies derived from different satellites. Climatologies from CHAMP and Formosat-3/COSMIC (F3C) agree very well if phase and orbit data from the same processing center are used. Climatologies from different F3C satellites show excellent agreement: After subtraction of the estimated respective sampling errors, altitude- and latitude-resolved seasonal dry temperature climatologies derived from F3C satellites in entirely different orbits agree to within < 0.1 K almost everywhere in the domain between 8 km and 35 km altitude. Mean differences (over the same domain) are smaller than 0.03 K in any case and can be as small as 0.003 K.
Acknowledgements The authors acknowledge GFZ (Potsdam, Germany) for the provision of CHAMP and GRACE RO data, in particular to J. Wickert and T. Schmidt for continuous support. ECMWF (Reading, UK) kindly provided access to their global operational analysis data. UCAR/CDAAC (Boulder, CO, USA) is acknowledged for the provision of Formosat-3/COSMIC and CHAMP data. The work was carried out with financial support from the Austrian Science Fund (FWF) under research grant P18837 (CLIMROCC). AKS was funded from FWF under research grant P18733 (INDICATE). UF received financial support from the Max Kade Foundation (New York, NY, USA) and from UCAR.
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