Publication Date:
2020-02-12
Description:
The GPS radio occultation experiment onboard the German CHAMP (CHAllenging Minisatellite Payload) satellite was started on February 11, 2001. During an one hour measurement period seven occultation events were recorded. Already these first measurements indicated that in spite of the activated anti-spoofing (A/S) mode of the GPS the state-of-the-art GPS flight receiver combined with favorable antenna characteristics allows for global atmosphere sounding with high accuracy and vertical resolution. More than 50,000 occultations are expected as of April 2002. The first year of the CHAMP occultation experiment is reviewed. The occultation infrastructure at the GeoForschungsZentrum (GFZ) Potsdam and the operational occultation data processing is characterized. An overview of GFZ’s operational data processing, the scientific data analysis and the results of the first year occultation experiment is given. The quality of CHAMP’s occultation data products (vertical atmospheric profiles) is evaluated. Results of data analysis using wave optic methods are presented, e.g. contributions from signals, reflected from Earth’s surface, were found in the occultation data in about 20-30% of the measurements using a radio holographic analysis. Furthermore, the termination of the Selective Availability (SA) mode of the GPS made the application of less-than-double-differencing techniques for GPS occultation analysis feasible. Results of occultation data processing using a space-based single differencing technique are compared with those generated by double differencing as a reference.
Keywords:
550 - Earth sciences
Type:
info:eu-repo/semantics/conferenceObject
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