Strategies for 4-D regional modeling of water vapour using GPS

  • S. H. Skone
  • S. M. Shrestha


Global Positioning System (GPS) signals experience ranging errors due to propagation through the neutral atmosphere. These range delays consist of a hydrostatic component, dependent on air pressure and temperature, and a wet delay dependent on water vapour pressure and temperature. Range delays arising from the hydrostatic component can be computed with accuracies of a few millimeters using existing models, provided that surface barometric or meteorological data are available. By using a regional network of GPS reference stations, it is possible to recover estimates of the Slant Wet Delay to all satellites in view. Observations of the Slant Wet Delay (SWD) can be used to model the vertical and horizontal structure of water vapour over a local area. These techniques are based on a tomographic approach using the SWD as input observables, where 4-D models of the wet refractivity may be derived. This method allows improved resolution of water vapour estimates for precise positioning applications and assimilation into Numerical Weather Predictions (NWP). In this paper we present strategies for real-time modeling of wet refractivity, with simulations and preliminary results of data processing for a regional GPS network in Southern California.

Key words

global positioning system troposphere meteorology tomography 

CLC number

P 228.4 P 457.6 


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  1. [1]
    Brunner F K, Gu M. An Improved Model for the Dual Frequency Ionospheric Correction of GPS Observations.Manuscripta Geodaetica, 1991,16: 205–214.Google Scholar
  2. [2]
    Ware R, Alber C, Rocken C,et al. Sensing Integrated Water Vapour Along GPS Ray Paths.Geophysical Research Letters, 1997,24: 417–420.CrossRefGoogle Scholar
  3. [3]
    Bevis M S, Businger S, Herring T A,et al. GPS Meteorology: Remote Sensing of Atmospheric Water Vapor Using the Global Positioning System.Journal of Geophysical Research, 1992,97(D14): 15787–15801.Google Scholar
  4. [4]
    Alber C, Ware R, Rocken C,et al. Obtaining Slant Path Phase Delays from GPS Double Differences.Geophysical Research Letters, 2000,27: 2661–2664.CrossRefGoogle Scholar
  5. [5]
    Zhang, J, Lachapelle G. Precise Estimation of Residual Tropospheric Delays Using a Regional GPS Network for RTK Applications.Journal of Geodesy, 2001,75: 255–266.CrossRefGoogle Scholar
  6. [6]
    Flores A, Ruffini G, Rius A. 4D Tropospheric Tomography Using GPS Slant Wet Delays.Annales Geophysicae, 2000,18: 223–234.CrossRefGoogle Scholar
  7. [7]
    Gradinarsky L, Jarlemark P. GPS Tomography Using the Permanent Network in Goteborg: Simulations.Proceedings of IEEE Positioning, Location and Navigation Symposium, Palm Springs: CA, April 15–18, 2002. 128–133.Google Scholar
  8. [8]
    Kuo Y.-H., Guo Y-R, Westwater E.R. Assimilation of Precipitable Water Measurements into a Mesoscale Numerical Model.Monthly Weather Review, 1993,121: 1215–1237.CrossRefGoogle Scholar
  9. [9]
    Kuo Y-H, Zou X, Guo Y-R. Variational Assimilation of Precipitable Water using Nonhydrostatic Mesoscale Adjoint Model. Part I: Moisture Retrieval and Sensitivity Experiments.Monthly Weather Review, 1996,124: 122–147.CrossRefGoogle Scholar
  10. [10]
    Hugentobler U, Schaer S, Fridez P.Bernese GPS Software Version 4.2. University of Berne: Astronomical Institute, 2001.Google Scholar
  11. [11]
    Rocken C, Johnson J, Neilan R,et al. The Measurement of Atmospheric Water Vapor: Radiometer Comparison and Spatial Variations.IEEE Trans Geosci and Remote Sensing, 1991,29: 3–8.CrossRefGoogle Scholar
  12. [12]
    Gelb A.Applied Optimal Estimation. Cambridge, Mass.: MIT Press, 1974.Google Scholar
  13. [13]
    Wickert J, Reigber C, Beyerle G,et al.. Atmosphere Sounding by GPS Radio Occultation: First Results from CHAMP.Geophysical Research Letters, 2001,28: 3263–3266.CrossRefGoogle Scholar

Copyright information

© Springer 2003

Authors and Affiliations

  1. 1.Department of Geomatics EngineeringUniversity of CalgaryCalgaryCanada

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