GFZ German research centre for geo sciences

GPS Radiooccultation with CHAMP


The German geoscience satellite CHAMP was launched on July 15, 2000 from the Russian COSMODROME Plesetsk, Russia (62.50 N, 40.30 E) into an almost circular, near polar orbit with an initial altitude of 454 km (eccentricity=0.004, inclination=87.2°). The scientific project was under lead from GFZ. The main goals are the determination Earth's gravity and magnetic field and the application of the GPS Radio Occultation (RO) technique for precise atmospheric sounding on a global scale. The CHAMP satellite burned up in the Earth's atmosphere in 2010 after an extremely successful mission period. The scientific data of the entire CHAMP mission are available at GFZ for the international user community.

The GPS RO measurements aboard CHAMP were activated for the first time on February 11, 2001, and indicated already the potential of CHAMP RO data to significantly improve the GPS occultation technique [5]. Numerous scientific studies related to data processing and the scientific application of CHAMP's data have proven this during the following years [1, 2, 6, 7]. Even 3 years after the end of the mission, CHAMP data are in use by a large number of research groups throughout the world. The data were and are also used to prepare several satellite missions with GPS RO capability, as, e.g., COSMIC, Metop and others. CHAMP was generating the first and unique long-term set of GPS RO data, which is used for climatological studies [4]. From 2006 until mission end the CHAMP data were also used to improve global weather forecasts [3]. The base for this application was the near-real time provision of RO data from CHAMP by GFZ [7].

Selected references:

[1] Arras C, Wickert J, Beyerle G, Heise S, Schmidt T, Jacobi C, A global climatology of ionospheric irregularities derived from GPS radio occultation. Geophys. Res. Lett., 35, doi; 10.1029/2008GL034158, 2008.

[2] Beyerle G, Schmidt T, Wickert J, Heise S, Rothacher M, König-Langlo G, Lauritsen K, Observations and simulations of receiver-induced refractivity biases in GPS radio occultation. J Geophys Res 111(D12), DOI 10.1029/2005JD006673, 2006.

[3] Healy S, Wickert J, Michalak G, Schmidt T, Beyerle G, Combined forecast impact of GRACE-A and CHAMP GPS radio occultation bending angle profiles. Atm Sci Letters 8:43–50, DOI 10.1002/asl.149, 2007.

[4] Schmidt T, Wickert J, Beyerle G, Heise S, Global tropopause height trends estimated from GPS radio occultation data. Geophys Res Lett 35 (L11806), DOI 10.1029/2008GL034012, 2008.

[5] Wickert J, Reigber C, Beyerle G, König R, Marquardt C, Schmidt T, Grunwaldt L, Galas R, Meehan TK, Melbourne WG, Hocke K, Atmosphere sounding by GPS radio occultation: First results from CHAMP. Geophys. Res. Lett. 28(17):3263–3266, 2001.

[6] Wickert, J., G. Beyerle, R. König, S. Heise, L. Grunwaldt, G. Michalak, Ch. Reigber, T. Schmidt, GPS radio occultation with CHAMP and GRACE: A first look at a new and promising satellite configuration for global atmospheric sounding, Annales Geophysicae, Vol. 23, 653-658, 2005.

[7] Wickert, J., G. Michalak, T. Schmidt, G. Beyerle, C.Z. Cheng, S.B. Healy, S. Heise, C.Y. Huang, N. Jakowski, W. Köhler, C. Mayer, D. Offiler, E. Ozawa, A.G. Pavelyev, M. Rothacher, B. Tapley, and C. Viehweg, GPS radio occultation: Results from CHAMP, GRACE and FORMOSAT-3/COSMIC, 20, 1, 35-50, doi:10.3319/TAO.2007.12.26.01(F3C), 2009.

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