Skip to main content

Volume 60 Supplement 5

Special Issue: Geohazards and the Role of Space-Born Observations

Ray-traced troposphere slant delays for precise point positioning


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.


  • 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.

    Article  Google Scholar 

  • 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.

    Article  Google Scholar 

  • 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.

    Article  Google Scholar 

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

    Google Scholar 

  • 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.

    Article  Google Scholar 

  • 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.

    Article  Google Scholar 

  • 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.

    Google Scholar 

  • 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.

    Google Scholar 

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

    Google Scholar 

  • 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.

    Article  Google Scholar 

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

    Article  Google Scholar 

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

    Article  Google Scholar 

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

    Article  Google Scholar 

  • 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.

    Article  Google Scholar 

  • 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.

    Article  Google Scholar 

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

    Google Scholar 

Download references

Author information

Authors and Affiliations


Corresponding author

Correspondence to Thomas Hobiger.

Rights and permissions

Open Access  This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.

The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

To view a copy of this licence, visit

Reprints and permissions

About this article

Cite this article

Hobiger, T., Ichikawa, R., Takasu, T. et al. Ray-traced troposphere slant delays for precise point positioning. Earth Planet Sp 60, e1–e4 (2008).

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Key words