Decorrelated GRACE time-variable gravity solutions by GFZ, and their validation using a hydrological model

Abstract

We have analyzed recent gravity recovery and climate experiment (GRACE) RL04 monthly gravity solutions, using a new decorrelating post-processing approach. We find very good agreement with mass anomalies derived from a global hydrological model. The post-processed GRACE solutions exhibit only little amplitude damping and an almost negligible phase shift and period distortion for relevant hydrological basins. Furthermore, these post-processed GRACE solutions have been inspected in terms of data fit with respect to the original inter-satellite ranging and to SLR and GPS observations. This kind of comparison is new. We find variations of the data fit due to solution post-processing only within very narrow limits. This confirms our suspicion that GRACE data do not firmly ‘pinpoint’ the standard unconstrained solutions. Regarding the original Kusche (J Geod 81:733–749, 2007) decorrelation and smoothing method, a simplified (order-convolution) approach has been developed. This simplified approach allows to realize a higher resolution—as necessary, e.g., for generating computed GRACE observations—and needs far less coefficients to be stored.

This is a preview of subscription content, access via your institution.

References

  1. Chambers D, Wahr J, Nerem RS (2004) Preliminary observations of global ocean mass variations with GRACE. Geophys Res Lett 33. doi:10.1029/2004GL020461

  2. Colombo OL (1986) Notes on the mapping of the gravity field using satellite data. In: Sünkel H (ed) Mathematical and numerical techniques in physical geodesy. Lecture notes in earth Sciences, vol 7. Springer, Berlin

  3. Davis J, Tamisea M, Elósegui P, Mitrovica J, Hill E (2008) A statistical filtering approach for Gravity Recovery and Climate Experiment (GRACE) gravity data. J Geophys Res/Solid Earth 113: B04410. doi:10.1029/2007JB005043

    Article  Google Scholar 

  4. Döll P, Kaspar F, Lehner B (2003) A global hydrological model for deriving water availability indicators: model tuning and validation. J Hydrol 270(1–2): 105–134

    Article  Google Scholar 

  5. Fenoglio-Marc L, Kusche J, Becker M (2006) Mass variation in the Mediterranean Sea and its validation by altimetry, steric and hydrologic fields. Geophys Res Lett 33. doi:10.1029/2006GL026851

  6. Flechtner F (2007) GFZ Level-2 processing standards document for level-2 product release 0004, GRACE 327-743, Rev. 1.0

  7. Güntner A (2008) Improvement of global hydrological models using GRACE data. Surv Geophys. doi:10.1007/s10712-008-9038-y

  8. Gunter B, Ries J, Bettadpur S, Tapley B (2006) A simulation study of the errors of omission and commission for GRACE RL01 gravity fields. J Geod. doi:10.1007/s00190-006-0083-3

  9. Han S-C, Simons F (2008) Spatiospectral localization of global geopotential fields from the gravity recovery and climate experiment (GRACE) reveals the coseismic gravity change owing to the 2004 Sumatra–Andaman earthquake. J Geophys Res/Solid Earth 113: B01405. doi:10.1029/2007JB004927

    Article  Google Scholar 

  10. Klees R, Revtova E, Gunter B, Ditmar P, Oudman E, Winsemius H, Savenije H (2008) The design of an optimal filter for monthly GRACE gravity models. Geophys J Int. doi:10.1011/j.1365-246X.2008.03922.x

  11. Kusche J (2007) Approximate decorrelation and non-isotropic smoothing of time-variable GRACE-type gravity field models. J Geod 81: 733–749. doi:10.1007/s00190-007-0143-3

    Article  Google Scholar 

  12. Parker RL (1994) Geophysical inverse theory. Princeton University Press, New Jersey

    Google Scholar 

  13. Petrovic S, Schmidt R, Wünsch J, Barthelmes F, Güntner A, Rothacher M (2007) Towards a characterization of temporal gravity field variations in GRACE observations and global hydrology models. J Mapping 18: 199–204

    Google Scholar 

  14. Schmidt R, Schwintzer P, Flechtner F, Reigber C, Güntner A, Döll P, Ramillien G, Cazenave A, Petrovic S, Jochmann H, Wünsch J (2006) GRACE observations of changes in continental water storage. Glob Planet Change 50(1–2): 112–126

    Article  Google Scholar 

  15. Schmidt R, Petrovic S, Güntner A, Barthelmes F, Wünsch J, Kusche J (2008a) Periodic components of water storage changes from GRACE and global hydrology models. J Geophys Res/Solid Earth. doi:10.1029/2007JB005363

  16. Schmidt R, Flechtner F, Meyer U, Neumayer K-H, Dahle C, König R, Kusche J (2008b) Hydrological signals observed by the GRACE satellites. Surv Geophys. doi:10.1007/s10712-008-9033-3

  17. Swenson S, Wahr J (2006) Post-processing removal of correlated errors in GRACE data. Geophys Res Lett 33: L08402. doi:10.1029/2005GL025285

    Article  Google Scholar 

  18. Swenson S, Wahr J (2007) Multi-sensor analysis of water storage variations in the Caspian Sea. Geophys Res Lett 34: L16401. doi:10.1029/2007GL030733

    Article  Google Scholar 

  19. Tapley B, Bettadpur S, Ries J, Thompson P, Watkins M (2004a) GRACE measurements of mass variability in the Earth system. Science 305: 503–505

    Article  Google Scholar 

  20. Tapley B, Bettadpur S, Watkins M, Reigber C (2004) The gravity recovery and climate experiment: Mission overview and early results. Geophys Res Lett 31: L09607. doi:10.1029/2004GL019920

    Article  Google Scholar 

  21. Wahr J, Molenaar M, Bryan F (1998) Time variability of the Earth’s gravity field: hydrological and oceanic effects and their possible detection using GRACE. J Geophy Res/Solid Earth 108(B12):30,205–30,229

  22. Wouters B, Schrama EJO (2007) Improved accuracy of GRACE gravity solutions through empirical orthogonal function filtering of spherical harmonics. Geophys Res Lett 34: L23711. doi:10.1029/2007GL032098

    Article  Google Scholar 

  23. Velicogna I, Wahr J (2006) Measurements of time-variable gravity show mass loss in Antarctica. Science 311: 1754

    Article  Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to J. Kusche.

Electronic supplementary material

The Below is the Electronic Supplementary Material.

ESM 1 (PDF 37kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Kusche, J., Schmidt, R., Petrovic, S. et al. Decorrelated GRACE time-variable gravity solutions by GFZ, and their validation using a hydrological model. J Geod 83, 903–913 (2009). https://doi.org/10.1007/s00190-009-0308-3

Download citation

Keywords

  • GRACE
  • Time-variable gravity
  • Smoothing
  • Decorrelation
  • Hydrological model validation