GPS Solutions

, Volume 10, Issue 3, pp 171–186

Analysis of GPS RTK performance using external NOAA tropospheric corrections integrated with a multiple reference station approach

  • Yong Won Ahn
  • G. Lachapelle
  • S. Skone
  • S. Gutman
  • S. Sahm
Original Article


For high-accuracy geodetic applications, time-variable tropospheric propagation delay errors limit global positioning system real-time kinematic positioning accuracy. Potential improvements in positioning accuracy are evaluated by using the National Oceanic and Atmospheric Administration (NOAA) real-time tropospheric corrections (herein called NOAA model) within a multiple reference station network approach. The results are compared with those for modified Hopfield tropospheric model corrections, for six scenarios in three geographical regions in the U.S. National Geodetic Survey network of Continuously Operating Reference Stations, for baseline lengths of 60~150 km. Analyses are conducted at rover locations for relatively humid days, and misclosures for various double difference observations are computed; these observations include each frequency (L1 and L2) and three linear combinations [wide lane, ionosphere free (IF), and geometry free]. The effectiveness of the network approach is demonstrated, with overall performance improvements of 15 and 19%, using the modified Hopfield and the NOAA model, respectively. The IF linear combination, a measure of tropospheric and orbital errors, shows a 3% improvement for the NOAA model compared with the modified Hopfield model.


  1. Ahn YW, Kim D, Dare P, Langley RB (2005) Long baseline GPS RTK performance in a marine environment using NWP ray-tracing technique under varying tropospheric conditions. In: Proceeding of ION GNSS 2005, Long Beach (in press)Google Scholar
  2. Alves P, Ahn YW, Lachapelle G (2003) The effects of network geometry on network RTK using simulated GPS data. In: Proceeding of ION GPS 2003. Portland, pp 1417–1427Google Scholar
  3. Alves P, Ahn YW, Liu J, Lachapelle G, Wolfe D, Cleveland A (2004) Improvements of USCG RTK positioning performance using external NOAA tropospheric corrections integrated with a multiple reference station approach. In: Proceedings of ION NTM 2004, San Diego, pp 689–698Google Scholar
  4. Behrend D, Cucurull L, Cardellach E, Rius A, Sedo MJ, Nothnagel A (2001) The use of NWP products in near real-time GPS data processing. In: Proceedings of ION GPS 2001, Salt Lake City, pp 2499–2506Google Scholar
  5. Bisnath SB, Dodd D, Cleveland A, Parsons M (2004) Analysis of the utility of NOAA-generated tropospheric refraction corrections for the next generation nationwide DGPS service. In: Proceeding of ION GNSS 2004, Long Beach, pp 1288–1297Google Scholar
  6. Brevis M, Brusinger S, Herring TA, Rocken C, Anthes RA, Ware RH (1992) GPS meteorology: remote sensing of atmospheric water vapor using the global positioning system. J Geophys Res 97(D14):15787–15801Google Scholar
  7. Cannon ME, Lachapelle G, Alves P, Fortes LP, Townsend B (2001) GPS RTK positioning using a regional reference network: theory and results. In: Proceedings of the 5th GNSS international symposium, SevilleGoogle Scholar
  8. Cannon ME, Lachapelle G, Ahn YW, Alves P, Lian P, Liu J, Morton A, Petovello M, Schleppe J (2004) Improving the existing USCG DGPS service: analysis of potential system upgrades and their effect on accuracy, reliability and integrity. Technical Report prepared for the United States Coast Guard, PortsmouthGoogle Scholar
  9. Chen R, Li X, Weber G (2004) Test results of an Internet RTK system based on the NTRIP protocol. The European GNSS 2004, RotterdamGoogle Scholar
  10. Cove K (2005) Improvements in GPS tropospheric delay estimation with numerical weather prediction. MScE Thesis, Department of Geodesy and Geomatics Engineering, University of New BrunswickGoogle Scholar
  11. Cove K, Santos MC, Wells D, Bisnah S (2004) Improved tropospheric delay estimation for long baseline, carrier phase differential GPS positioning in a coastal environment. In: Proceeding of ION GNSS 2004, Long Beach, pp 925–932Google Scholar
  12. Elgered G (1993) Tropospheric radio-path delay from ground-based microwave-radiometry. In: Janssen MA (ed) Atmospheric remote sensing by microwave radiometry. Wiley, New York, pp 215–258Google Scholar
  13. Fortes LP, Cannon ME, Skone S, Lachapelle G (2001) Improving a multi-reference GPS station network method for OTF positioning in the St. Lawrence Seaway. In: Proceedings of ION GPS 2001, Salt Lake City, pp 404–414Google Scholar
  14. Fotopoulos G, Cannon M (2000) Investigation of the spatial decorrelation of GPS carrier phase errors using a regional reference station network. In: Proceedings of the World Congress of International Association, San DiegoGoogle Scholar
  15. Goad CC, Goodman L (1974) A modified Hopfield tropospheric refraction correction model. The American Geophysical Union, San Francisco, pp 28Google Scholar
  16. Grejner-Brzezinska DA, Kashani I, Wielgosz P (2004) Analysis of the network geometry and station separation for network-based RTK. In: Proceeding of ION NTM 2004, San Diego, pp 469–474Google Scholar
  17. Gutman SI, Benjamin SG (2001) The role of ground-based GPS meteorological observations in numerical weather prediction. GPS Solutions 4(4):16–24CrossRefGoogle Scholar
  18. Gutman S, Fuller-Rowell T, Robinson D (2003) Using NOAA atmospheric models to improve ionospheric and tropospheric corrections. U.S. Coast Guard differential GPS symposium, Portsmouth. Scholar
  19. Jensen ABO (2002) Numerical weather prediction for network RTK. PhD Thesis, University of Copenhagen, Publication Series 4, vol 10, National Survey and Cadastre, DenmarkGoogle Scholar
  20. Kashani I, Grejner-Brzezinska DA, Wielgosz P (2004) Towards instantaneous network-based RTK GPS over 100 km distances. In: Proceeding of ION 60th annual meeting, Dayton, pp 679–685Google Scholar
  21. Kim D, Langley RB, Kim JH, Kim SN (2003) A gantry crane auto-steering system based on GPS RTK technology. The European GNSS 2003, GrazGoogle Scholar
  22. Lachapelle G, Townsend B, Alves P, Fortes LP, Cannon ME (2000) RTK positioning using a reference network. In: Proceedings of ION GPS 2000, Alexandria, pp 1165–1171Google Scholar
  23. Landau H, Vollath U, Chen X (2003) Virtual reference stations versus broadcast solutions in network RTK: advantages and limitations. The European GNSS 2003, GrazGoogle Scholar
  24. NOAA (2001) NOAA/FSL ground-based GPS integrated precipitable water vapor real time water vapor interface. http://www.gpsmet.noaa.govGoogle Scholar
  25. NOAA (2004) NOAA/FSL ground-based GPS meteorology (GPS-Met). Scholar
  26. Niell AE (1996) Global mapping functions for the atmosphere delay at radio wavelengths. J Geophys Res 101(B2):3227–3246CrossRefGoogle Scholar
  27. Nievinski F, Cover K, Santos M, Wells D, Kingdon R (2005) Range-extended GPS kinematic positioning using numerical weather prediction model. In: Proceedings of ION annual meeting, Boston (in press)Google Scholar
  28. Odijk D (1999) Stochastic modelling of the ionosphere for fast GPS ambiguity resolution. In: Proceedings of the general assembly of the international association of geodesy, Birmingham, England, International Association of Geodesy, Springer, Berlin Heidelberg New York, vol 121, pp 387–392Google Scholar
  29. Pany T, Pesec P, Stangl G (2001) Elimination of tropospheric path delays in GPS observations with the ECMWF numerical weather model. Phys Chem Earth A 26(6–8):487–492CrossRefGoogle Scholar
  30. Raquet J (1998) Development of a method for kinematic GPS carrier-phase ambiguity resolution using multiple reference receivers. PhD Thesis, UCGE Report Number 20116, University of CalgaryGoogle Scholar
  31. Raquet J, Lachapelle G (2000) Development and testing of a kinematic carrier-phase ambiguity resolution method using a reference receiver network. The Institute of Navigation, Alexandria, vol 46, no. 4, pp 283–295Google Scholar
  32. Raquet J, Lachapelle G, Melgard TE (1998) Test of a 400 km×600 km network of reference receivers for precise kinematic carrier-phase positioning in Norway. In: Proceedings of ION NTM 1998, Nashville, pp 407–416Google Scholar
  33. Rizos C (2002) Network RTK research and implementation: a geodetic perspective. J Glob Position Syst 1(2):144–150CrossRefGoogle Scholar
  34. Rocken C, Mervart L, Lukes Z, Johnson J, Kanzaki M, Kakimoto H, Iotake Y (2004) Testing a new network RTK software system. In: Proceeding of ION GNSS 2004, Long Beach, pp 2831–2838Google Scholar
  35. Rothacher M, Beutler G (2002) Advanced aspects of satellite positioning. Lecture notes of ENGO 699.80, University of CalgaryGoogle Scholar
  36. Schuler T (2001) On ground-based GPS tropospheric delay estimation. PhD Thesis, University of MunchenGoogle Scholar
  37. Talbot N, Lu G, Allison T (2002) Broadcast network RTK—transmission standards and results. In: Proceedings of the 15th international technical meeting, Portland, OregonGoogle Scholar
  38. Thayer GD (1974) An improved equation for the radio refractive index of air. Radio Sci 9(10):803–807CrossRefGoogle Scholar
  39. Wanninger L (1999) The performance of virtual reference stations in active geodetic GPS-networks under solar maximum conditions. In: Proceeding of ION GPS 1999, Nashville, pp 1419–1427Google Scholar
  40. Zhang J (1999) Investigation into the estimation of residual tropospheric delays in a GPS network. MSc Thesis, University of CalgaryGoogle Scholar
  41. Zhang Y, Barton C (2005) Comparison of real-time troposphere correction techniques for high performance DGPS application. In: Proceeding of ION NTM 2005, San Diego, pp 666–684Google Scholar

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Yong Won Ahn
    • 1
  • G. Lachapelle
    • 1
  • S. Skone
    • 1
  • S. Gutman
    • 2
  • S. Sahm
    • 2
  1. 1.Department of Geomatics EngineeringUniversity of CalgaryCalgaryCanada
  2. 2.GPS-Met Observing Systems Branch, Demonstration DivisionNOAA Forecast Systems LaboratoryBoulderUSA

Personalised recommendations