Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 4 6 2004 10.5194/acpd-4-7837-2004 http://www.atmos-chem-phys-discuss.net/4/7837/2004/ http://www.atmos-chem-phys-discuss.net/4/7837/2004/acpd-4-7837-2004.html http://www.atmos-chem-phys-discuss.net/4/7837/2004/acpd-4-7837-2004.pdf 7837 7857 2004-12-01 GPS radio occultation with CHAMP: monitoring of climate change parameters T. Schmidt tschmidt@gfz-potsdam.de S. Heise J. Wickert G. Beyerle C. Reigber GeoForschungsZentrum Potsdam, Department 1: Geodesy and Remote Sensing, Potsdam, Germany The Global Positioning System (GPS) radio occultation (RO) technique offers a valuable new data source for global and continuous monitoring of the Earth's atmosphere. Refractivity, temperature and water vapor profiles with high accuracy and vertical resolution can be derived from this method. The GPS RO technique requires no calibration, is not affected by clouds, aerosols or precipitation, and the occultations are almost uniformly distributed over the globe. In this paper the potential of GPS RO for monitoring of the temperature is demonstrated exemplarily for the tropical upper troposphere and lower stratosphere (UTLS) region using GPS RO data from the German CHAMP (CHAllenging Minisatellite Payload) satellite mission. In addition, results of a 1DVAR retrieval scheme to derive tropospheric water vapor profiles using ECMWF data as background will be discussed. CHAMP RO data are available since 2001 with up to 200 high resolution temperature profiles per day. The temperature bias between CHAMP temperature profiles and radiosonde data as well as ECMWF analyses is less than 0.5 K between 300–30 hPa. The CHAMP RO experiment generates the first long-term RO data set. Other satellite missions will follow (GRACE, TerraSAR-X, COSMIC, METOP) generating some thousand profiles of atmospheric parameters daily.