Approach and quality assessment of precise GPS data processing at the UCAR CDAAC [presentation]

The COSMIC Data Analysis and Archival Center (CDAAC) at UCAR has processed radio occultation data from the GPS/MET, CHAMP, and SAC-C missions in both postprocessing and near real time modes of operation. The GPS data processing at the CDAAC is performed with the Bernese software package. A recent upgrade of the Bernese software to version 5.0 has improved the CDAAC CHAMP satellite velocity estimation from ~0.5 mm/sec 3D rms to approximately the ~0.1 mm/sec level in post-processing when using a ground GPS network with approximately 50 stations. This improved orbit quality will increase the accuracy of radio occultation retrievals, especially at high altitudes. In this paper, the approaches used for postprocessed and near real-time precise orbit determination of LEO satellites at the CDAAC are described. An assessment of the orbit quality is then performed using CHAMP GPS data.