A Priori Gradients in the Analysis of Space Geodetic Observations

  • J. Böhm
  • L. Urquhart
  • P. Steigenberger
  • R. Heinkelmann
  • V. Nafisi
  • H. Schuh
Conference paper
Part of the International Association of Geodesy Symposia book series (IAG SYMPOSIA, volume 138)

Abstract

We introduce a static a priori gradient model (APG) based on a spherical harmonic expansion up to degree and order nine to describe the azimuthal asymmetry of tropospheric delays. APG is determined from climatology data of the European Centre for Medium-Range Weather Forecasts (ECMWF), and the refined model can be used in the analysis of observations from Global Navigation Satellite Systems (GNSS) and Very Long Baseline Interferometry (VLBI). Comparisons reveal that gradients estimated in GNSS analysis are mostly smaller than those provided by APG. This difference is also confirmed by station and source coordinate changes if APG is used in GNSS and VLBI analysis.

Keywords

Tropospheric delay Tropospheric gradients VLBI GNSS APG 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • J. Böhm
    • 1
  • L. Urquhart
    • 2
  • P. Steigenberger
    • 3
  • R. Heinkelmann
    • 4
  • V. Nafisi
    • 1
    • 5
    • 6
  • H. Schuh
    • 1
  1. 1.Vienna University of TechnologyViennaAustria
  2. 2.University of New BrunswickFrederictonCanada
  3. 3.Technische Universität MünchenMunichGermany
  4. 4.Deutsches Geodätisches ForschungsinstitutMunichGermany
  5. 5.University of TehranTehranIran
  6. 6.University of IsfahanIsfahanIran

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