An Analysis of the Lower Tropospheric Refractivity Bias by Heuristic Sliding Spectral Methods

  • Georg Beyerle
  • Jens Wickert
  • Torsten Schmidt
  • Rolf König
  • Christoph Reigber


The canonical transform (CT) and full spectrum inversion (FSI) method together with their heuristic sliding spectral modifications are validated using end-to-end simulation data and one week of CHAMP observations. In general, we observe a pronounced correlation between small refractivity biases and enhanced penetration altitudes. Processing of simulated occultation data shows that the heuristic methods exhibit smaller retrieval errors vindicating the assertion that the sliding spectral approaches react less sensitive to receiver tracking errors. The corresponding mean retrievals errors found in the CHAMP data analysis, however, are consistent within 0.5%; differences are observed with respect to penetration altitudes and the retrieval errors' standard deviations.

Key words

Remote sensing GPS radio occultation canonical transform full spectrum inversion refractivity bias 


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  1. 1.
    Ao CO, Meehan TK, Hajj GA, Mannucci AJ, and Beyerle G (2003) Lowertroposphere refractivity bias in GPS occultation retrievals. J Geophys Res 108(D18): doi:10.1029/2002JD003216.Google Scholar
  2. 2.
    Beyerle G, Gorbunov ME, and Ao CO (2003) Simulation studies of GPS radio occultation measurements. Radio Sci 38(5): doi:10.1029/2002RS002800.Google Scholar
  3. 3.
    Beyerle G, Wickert J, Schmidt T, and Reigber Ch (2003) Atmospheric sounding by GNSS radio occultation: An analysis of the negative refractivity bias using CHAMP observations. J Geophys Res 108: doi:10.1029/2003JD003922.Google Scholar
  4. 4.
    Gorbunov ME (2002) Canonical transform method for processing GPS radio occultation data in lower troposphere. Radio Sci 37: doi:10.1029/2000RS002592.Google Scholar
  5. 5.
    Gorbunov ME (2002) Radio-holographic analysis of Microlab-1 radio occultation data in the lower troposphere. J Geophys Res 107(D12): doi:10.1029/2001JD000889.Google Scholar
  6. 6.
    Gorbunov ME (2002) Radioholographic analysis of radio occultation data in multipath zones. Radio Sci 37(1): doi:10.1029/2000RS002577.Google Scholar
  7. 7.
    Gorbunov ME, Gurvich AS, and Bengtsson L (1996) Advanced algorithms of inversion of GPS/MET satellite data and their application to reconstruction of temperature and humidity. Report 211, Max-Planck-Institut für Meteorologie, Germany, Hamburg.Google Scholar
  8. 8.
    Hajj GA, Ao CO, Iijima BA, Kuang D, Kursinski ER, Mannucci AJ, Meehan TK, Romans LJ, de la Torre Juarez M, and Yunck TP (2003) CHAMP and SAC-C atmospheric occultation results and intercomparisons. J Geophys Res, submitted.Google Scholar
  9. 9.
    Jensen AS, Lohmann M, Benzon H-H, and Nielsen A (2003) Full spectrum inversion of radio occultation signals. Radio Sci 38(3): doi:10.1029/2002RS002763.Google Scholar
  10. 10.
    Karayel ET and Hinson DP (1997) Sub-Fresnel-scale vertical resolution in atmospheric profiles from radio occultation. Radio Sci 32(2): 411–423.CrossRefGoogle Scholar
  11. 11.
    Marquardt C, Schöllhammer K, Beyerle G, Schmidt T, Wickert J, and Reigber C (2003) Validation and data quality of CHAMP radio occultation data. In: Reigber C, Lühr H, and Schwintzer P, eds, First CHAMP mission results for gravity, magnetic and atmospheric studies, Springer-Verlag, Berlin: 384–396.Google Scholar
  12. 12.
    Reigber Ch, Lühr H, and Schwintzer P (2000) CHAMP mission status and perspectives. Suppl to EOS Transactions, AGU 81(48): F307.Google Scholar
  13. 13.
    Reigber Ch, Lühr H, and Schwintzer P (2002) CHAMP mission status. Adv Space Res 30(2): 129–134.CrossRefGoogle Scholar
  14. 14.
    Rocken C, Anthes R, Exner M, Hunt D, Sokolovskiy S, Ware R, Gorbunov M, Schreiner W, Feng D, Herman B, Kuo Y-H, and Zou X (1997) Analysis and validation of GPS/MET data in the neutral atmosphere. J Geophys Res 102(D25): 29,849–29,866.CrossRefGoogle Scholar
  15. 15.
    Sokolovskiy S (2003) Effect of superrefraction on inversions of radio occultation signals in the lower troposphere. Radio Sci 38(3): doi:10.1029/2002RS002728.Google Scholar
  16. 16.
    Sokolovskiy SV (2001) Modeling and inverting radio occultation signals in the moist troposphere. Radio Sci 36(3): 441–458.CrossRefGoogle Scholar
  17. 17.
    Sokolovskiy SV (2001) Tracking tropospheric radio occultation signals from low Earth orbit. Radio Sci 36(3): 483–498.CrossRefGoogle Scholar
  18. 18.
    Wickert J, Schmidt T, Beyerle G, König R, Reigber Ch, and Jakowski N (2003) The radio occultation experiment aboard CHAMP: Operational data processing and validation of atmospheric parameters. J Meteorol Soc Jpn 82(1B):381–395.CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2005

Authors and Affiliations

  • Georg Beyerle
    • 1
  • Jens Wickert
    • 1
  • Torsten Schmidt
    • 1
  • Rolf König
    • 1
  • Christoph Reigber
    • 1
  1. 1.Dept. 1: Geodesy and Remote SensingGeoForschungsZentrum Potsdam (GFZ)PotsdamGermany

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