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Ray-traced troposphere slant delays for precise point positioning

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Precise satellite orbits and clock information for global navigation satellite systems (GNSS) allow zero-difference position solutions, also known as precise point positioning (PPP) to be calculated. In recent years numerical weather models (NWM) have undergone an improvement of spatial and temporal resolution. This makes them not only useful for the computation of mapping functions but also allows slant troposphere delays from ray-tracing to be obtained. For this study, such ray-traced troposphere corrections have been applied to code and phase observations of 13 sites from the International GNSS Service (IGS) receiver network, which are located inside the boundaries of the Japanese Meteorological Agency (JMA) meso-scale weather model, covering a period of 4 months. The results from this approach are presented together with a comparison to standard PPP processing results. Moreover the advantages and caveats of the introduction of ray-traced slant delays for precise point positioning are discussed.


  1. Boehm, J., A. Niell, P. Tregoning, and H. Schuh, Global Mapping Function (GMF): A new empirical mapping function based on numerical weather model data, Geophys. Res. Lett., 33, L07304, doi:10. 1029/2005GL025546, 2006a.

  2. Boehm, J., B. Werl, and H. Schuh, Troposphere mapping functions for GPS and very long baseline interferometry from European Centre for Medium-Range Weather Forecasts operational analysis data, J. Geo-phys. Res., 111, B02406, doi:10.1029/2005JB003629, 2006b.

  3. Chen, G. and T. A. Herring, Effects of atmospheric azimuthal asymmetry on the analysis of space geodetic data, J. Geophys. Res., 102(B9), 20,489–20,502, doi:10.1029/97JB01739, 1997.

  4. Gurtner, W., RINEX: The Receiver-Independent Exchange Format, GPS World, 5(7), 48–52, 2000.

  5. Haase, J. S., H. Vedel, M. Ge, and E. Calais, GPS zenith tropospheric delay (ZTD) variability in the Mediterranean, Phys. Chem. Earth, Solid Earth Geodes., 26(6–8), 439–443, 2001.

  6. Harris, R. Benjamin and R. G. Mach, GPSTk-An Open Source GPS Toolkit, GPS Solutions, 11(2), doi:10.1007/s10291-006-0043-7, 2007.

  7. Hobiger, T., R. Ichikawa, Y. Koyama, and T. Kondo, Kashima Ray-Tracing Service (KARATS)—Fast ray-tracing through numerical weather models for real-time positioning applications, NICT IVS Technical Development Center News, 82, 16–19, 2007.

  8. Ishikawa, Y., Development of a mesoscale 4-dimensional variational data assimilation (4D-Var) system at JMA, Proceedings of the 81st Annual Meeting of the AMS: Precipitation Extremes: Prediction, Impacts and Responses, P2.45, 2001.

  9. JMA, Outline of the operational numerical weather prediction at the Japanese Meteorological Agency, 158 pp, 2002.

  10. Meindl, M., S. Schaer, U. Hugentobler, and G. Beutler, Tropospheric Gradient Estimation at CODE: Results from Global Solutions, J. Meteorol. Soc. Jpn., 82, 331–338, doi:10.2151/jmsj.2004.331, 2004.

  11. Niell, A. E., Global mapping functions for the atmosphere delay at radio wavelengths, J. Geophys. Res., 101(B2), 3227–3246, 1996.

  12. Niell, A. E., Improved atmospheric mapping functions for VLBI and GPS, Earth Planets Space, 52, 699–702, 2000.

  13. Niell, A. E., Preliminary evaluation of atmospheric mapping functions based on numerical weather models, Phys. Chem. Earth, 26, 475–480, 2001.

  14. Saastamoinen, J., Atmospheric correction for the troposphere and stratosphere in radio ranging of satellites, The Use of Artificial Satellites for Geodesy, Geophys. Monogr. AGU, 15, 247–251, 1972.

  15. Schmid, R., P. Steigenberger, G. Gendt, M. Ge, and M. Rothacher, Generation of a consistent absolute phase-center correction model for GPS receiver and satellite antennas, J. Geodes., 81(12), 781–798, doi:10. 1007/s00190-007-0148-y, 2007.

  16. Takasu, T. and S. Kasai, Evaluation of GPS Precise Point Positioning (PPP) Accuracy, IEIC Technical Report, 105(208), 40–45, 2005.

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Correspondence to Thomas Hobiger.

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Key words

  • GPS
  • troposphere
  • ray-tracing
  • PPP