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GPS Solutions

, Volume 14, Issue 2, pp 165–175 | Cite as

Low-degree earth deformation from reprocessed GPS observations

  • Mathias FritscheEmail author
  • R. Dietrich
  • A. Rülke
  • M. Rothacher
  • P. Steigenberger
Original Article

Abstract

Surface mass variations of low spherical harmonic degree are derived from residual displacements of continuously tracking global positioning system (GPS) sites. Reprocessed GPS observations of 14 years are adjusted to obtain surface load coefficients up to degree n max = 6 together with station positions and velocities from a rigorous parameter combination. Amplitude and phase estimates of the degree-1 annual variations are partly in good agreement with previously published results, but also show interannual differences of up to 2 mm and about 30 days, respectively. The results of this paper reveal significant impacts from different GPS observation modeling approaches on estimated degree-1 coefficients. We obtain displacements of the center of figure (CF) relative to the center of mass (CM), Δr CF–CM, that differ by about 10 mm in maximum when compared to those of the commonly used coordinate residual approach. Neglected higher-order ionospheric terms are found to induce artificial seasonal and long-term variations especially for the z-component of Δr CF–CM. Daily degree-1 estimates are examined in the frequency domain to assess alias contributions from model deficiencies with regard to satellite orbits. Finally, we directly compare our estimated low-degree surface load coefficients with recent results that involve data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission.

Keywords

GPS Surface mass redistribution Terrestrial reference frame 

Notes

Acknowledgments

We thank the International GNSS Service for providing the observation data via its data centers. Our sincere thanks go to the CODE Analysis Center team for their cooperation within the reprocessing project. This research was funded by the German Research Foundation (DFG). Figures were generated with the Generic Mapping Tools (http://gmt.soest.hawaii.edu/; Wessel and Smith 1991). The helpful comments of two anonymous reviewers are gratefully acknowledged.

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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Mathias Fritsche
    • 1
    Email author
  • R. Dietrich
    • 1
  • A. Rülke
    • 1
  • M. Rothacher
    • 2
  • P. Steigenberger
    • 3
  1. 1.Institut für Planetare GeodäsieTechnische Universität DresdenDresdenGermany
  2. 2.Institut für Geodäsie und PhotogrammetrieEidgenössische Technische Hochschule ZürichZurichSwitzerland
  3. 3.Institut für Astronomische und Physikalische GeodäsieTechnische Universität MünchenMunichGermany

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