Generation and Assessment of VMF1-Type Grids Using North-American Numerical Weather Models

  • Landon Urquhart
  • Marcelo C. SantosEmail author
  • Felipe G. Nievinski
  • Johannes Böhm
Conference paper
Part of the International Association of Geodesy Symposia book series (IAG SYMPOSIA, volume 139)


Numerical weather models (NWM) have become an important source of atmospheric data for modeling error sources in geodetic positioning. One example of this is the development of the Vienna Mapping Functions (VMF1) and ray-traced zenith delays which are derived from the European Centre for Medium-range Weather Forecasts (ECMWF) datasets. These products are provided on an operational basis through the GGOS Atmosphere project. In general, relatively little consideration has been given to the choice of NWM on the derived mapping functions and zenith delay products. In this investigation we compare the gridded-VMF1 mapping functions and ray-traced zenith delays derived from the ECMWF to equivalent products derived by ray-tracing through the National Center for Environmental Prediction (NCEP) Reanalysis model. We have chosen to compare the gridded version of these products as they are available for any location on Earth, rather than only specific stations and have been shown to be essentially equivalent in terms of accuracy. This paper also includes a discussion about a systematic production of gridded-VMF1 and ray-traced zenith delays derived from the NCEP datasets (and from the Canadian Meteorological Center GEM model) on an operational basis. The benefits of the service would include: (1) a backup in the event of the ECMWF VMF1 or zenith delays being unavailable; (2) greater compatibility with other NWM derived corrections, such as atmospheric pressure loading and; (3) the availability of tropospheric delay products derived from an independent source and ray-tracing algorithms should provide more robustness for combination products which use these models.


Mapping functions Neutral atmosphere Tropospheric delay Vienna Mapping Functions 



The authors acknowledge Matthias Madzak (TU Vienna) for processing the VLBI results, the weather agencies (ECMWF, NCEP and CMC) for providing access to the NWM data, and Natural Sciences and Engineering Research Council of Canada (NSERC) and the Austrian Science Fund (FWF, project P20902) for funding the research. Dow et al. 2009 is kindly acknowledged for the IGS products


  1. Boehm J, van Dam T (2009) Modeling deficiencies and modeling based on external data. In: Second GGOS unified analysis workshop, IERS, Grand Hyatt, 11–12 December (oral presentation)Google Scholar
  2. Boehm J, Niell AE, Tregoning P, Schuh H (2006a) Global Mapping Function (GMF): a new empirical mapping function based on numerical weather model data. Geophys Res Lett 33:L07304. doi: 10.1029/2005GL025546
  3. Boehm J, Werl B, Schuh H (2006b) Troposphere mapping functions for GPS and very long baseline interferometry from European Centre for medium-range weather forecasts operational analysis data. J Geophys Res 111:B02406. doi: 10.1029/2005JB003629
  4. Boehm J, Kouba J, Schuh H (2008) Forecast Vienna mapping functions 1 for realtime analysis of space geodetic observations. J Geodesy 83(5):397–401. doi: 10.1007/s00190-008-0216-y CrossRefGoogle Scholar
  5. Dow JM, Neilan RE, Rizos C (2009) The international GNSS Service in a changing landscape of global navigation satellite systems. J Geodesy 83:191–198. doi: 10.1007/s00190-008-0300-3 CrossRefGoogle Scholar
  6. Fund F, Morel L, Mocquet A (2009) Discussion and recommendations about the height correction for a priori zenith hydrostatic delays derived from ECMWF data [on-line].
  7. Herring TA (1992) Modelling atmospheric delays in the analysis of space geodetic data. In: de Munck JC, Th Spoelstra TA (eds) Proceedings of the symposium refraction of transatmospheric signals in Geodesy, No. 36, Netherlands Geodetic Commission, The Hague, 19–22 May, pp. 157–164Google Scholar
  8. Kouba J (2008) Implementation and testing of the gridded Vienna Mapping Function 1 (VMF1). J Geodesy 82(4):193–205. doi: 10.1007/s00190-007-0170-0 CrossRefGoogle Scholar
  9. Marini JW (1972) Correction of satellite tracking data for an arbitrary tropospheric profile. Radio Sci 7(2):223–231. doi: 10.1029/RS007i002p00223 CrossRefGoogle Scholar
  10. Niell AE (1996) Global mapping functions for the atmosphere delay at radio wavelengths. J Geophys Res 101(B2):3227–3246. doi: 10.1029/95JB03048 CrossRefGoogle Scholar
  11. Nievinski FG (2009) Ray-tracing options to mitigate the neutral atmosphere delay in GPS. M.Sc.E. Thesis, Department of Geodesy and Geomatics Engineering technical report no. 262, University of New Brunswick, Fredericton, New Brunswick, 232 ppGoogle Scholar
  12. Nievinski FG, Santos MC (2010) Ray-tracing options to mitigate the neutral atmosphere delay in GPS. Geomatica 64(2):191–207Google Scholar
  13. Petit G, Luzum B (eds) (2010) IERS conventions (2010) (IERS technical note; 36). Verlag des Bundesamts für Kartographie und Geodäsie, Frankfurt am Main, 179 ppGoogle Scholar
  14. Saastamoinen J (1972) Atmospheric correction for the troposphere and stratosphere in radio ranging of satellites. In: Henriksen SW, Mancini A, Chovitz BH (eds) The use of artificial satellites for Geodesy, vol. 15 of Geophysical monograph series. American Geophysical Union, Washington, DC, pp 247–251. ISBN 0-87590-015-1Google Scholar
  15. Teke K, Böhm J, Nilsson T, Schuh H, Steigenberger P, Dach R, Heinkelmann R, Willis P, Haas R, García-Espada S, Hobiger T, Ichikawa R, Shimizu S (2011) Multi-technique comparison of troposphere zenith delays and gradients during CONT08. J Geodesy 85(7):395–413. doi: 10.1007/s00190-010-0434-y CrossRefGoogle Scholar
  16. Tesmer V, Boehm J, Heinkelmann R, Schuh H (2007) Effect of different tropospheric mapping functions on the TRF, CRF and position time-series estimated from VLBI. J Geodesy 81:409–421. doi: 10.1007/s00190-006-0126-9 CrossRefGoogle Scholar
  17. Urquhart L (2010) Assessment of tropospheric slant factor models: comparison with three dimensional ray-tracing and impact of geodetic positioning. M.Sc.E thesis, Dept of Geodesy and geomatics Engineering technical report 275, University of New Brunswick, Fredericton, 166 ppGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Landon Urquhart
    • 1
  • Marcelo C. Santos
    • 1
    Email author
  • Felipe G. Nievinski
    • 2
  • Johannes Böhm
    • 3
  1. 1.Department of Geodesy and Geomatics EngineeringUniversity of New BrunswickFrederictonCanada
  2. 2.Department of Aerospace Engineering SciencesUniversity of ColoradoBoulderUSA
  3. 3.Institute of Geodesy and GeophysicsVienna University of TechnologyViennaAustria

Personalised recommendations