Publications

The standard method for the processing of CHAMP’s (CHAllenging Minisatellite Payload) GPS occultation data at the GeoForschungsZentrum (GFZ) Potsdam is the double difference technique to correct for satellite clock errors. In order to apply this technique the implementation of a global fiducial GPS ground network is necessary. This network (“High Rate and Low Latency network”) was installed jointly by GFZ and Jet Propulsion Laboratory (JPL) in preparation of the CHAMP occultation experiment and is operated jointly by both institutes. In the current configuration (January 2002) it consists of 28 stations. Various aspects of utilizing the ground station data for occultation processing are discussed. E.g. a correlation between the network topology and the global distribution of ground data redundancy for occultation processing is given. Furthermore the influence of an acquisition rate reduction (compared to the standard 1 Hz rate) to the quality of the atmospheric profiles is discussed. A data set of occultations for a 3-day period in April 2001 is processed with three different acquisition rates (5, 10 and 30 Hz). The results are compared with profiles, generated using the standard acquisition rate (1 Hz) as a reference. In addition, the profiles are compared with ECMWF meteorological analyses. The time delay of ground station data availability is discussed with respect to an operational occultation data provision of vertical atmospheric profiles for Numerical Weather Prediction.

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Wickert, J.; Galas, R.; Schmidt, T.; Reigber, C.; Förste, C.; Ramatschi, M. (2002): GPS Ground station data for the CHAMP occultation experiment. 27th General Assembly European Geophysical Society (EGS) (Nice France 2002).