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A Simulation Study Discussing the GRACE Baseline Accuracy

  • U. MeyerEmail author
  • F. Flechtner
  • R. Schmidt
  • B. Frommknecht
Conference paper
Part of the International Association of Geodesy Symposia book series (IAG SYMPOSIA, volume 135)

Abstract

The twin GRACE-A and -B satellites are in orbit since more than 6 years and still perform well. They deliver gravity data of unprecedented accuracy, which enables hydrologists, oceanographers and geophysicists to study the temporal variations of the Earth’s gravity field. But the baseline accuracy computed in a pre-launch simulation study (Kim, 2000) has not yet been reached by a factor of about 15. We therefore have to raise the question: are there improvements in the processing of GRACE data possible? To answer this question, a simulation study was performed, using the same software, processing strategy, background models and standards used at GFZ for the analysis of real GRACE data.

We present the results and analysis of this simulation study. Initially a closed loop simulation shows, that GFZ’s EPOS software is numerically stable. The GRACE orbit geometry is sufficient and the sampling adequate to solve for monthly gravity fields at least up to degree and order 150. The estimation of instrument parameters as suggested by Kim (2000) does not absorb the gravity signal, but greatly reduces systematic effects in the observations. The accelerometer noise proved to be an important reason for not reaching the baseline accuracy with the processing strategy used so far. Additional accelerometer parameters do not really help, but the shortening of arcs gives promising results. Different background model errors were introduced and the ocean tide model turned out to be a probable error source, while atmospheric tides play a minor role.

Keywords

GRACE Satellite gravimetry Simulation study 

Notes

Acknowledgements

This study has been sponsored by the Geotechnologien programme of BMBF and DFG. The author wishes to thank two anonymous reviewers for their helpful comments.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2010

Authors and Affiliations

  • U. Meyer
    • 1
    Email author
  • F. Flechtner
    • 1
  • R. Schmidt
    • 1
    • 2
  • B. Frommknecht
    • 3
    • 4
  1. 1.Deutsches GeoForschungsZentrum (GFZ), Helmholtz Centre PotsdamWesslingGermany
  2. 2.Astrium GmbHMünchenGermany
  3. 3.Institut für Astronomische und Physikalische Geodäsie (IAPG), Technische Universität MünchenMünchenGermany
  4. 4.ESA/ESRINFrascatiItaly

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