Journal of Geodesy

, Volume 81, Issue 4, pp 237–245 | Cite as

Attenuation effect on seasonal basin-scale water storage changes from GRACE time-variable gravity

  • J. L. Chen
  • C. R. Wilson
  • J. S. Famiglietti
  • Matt Rodell
Original Article

Abstract

In order to effectively recover surface mass or geoid height changes from the gravity recovery and climate experiment (GRACE) time-variable gravity models, spatial smoothing is required to minimize errors from noise. Spatial smoothing, such as Gaussian smoothing, not only reduces the noise but also attenuates the real signals. Here we investigate possible amplitude attenuations and phase changes of seasonal water storage variations in four drainage basins (Amazon, Mississippi, Ganges and Zambezi) using an advanced global land data assimilation system. It appears that Gaussian smoothing significantly affects GRACE-estimated basin-scale seasonal water storage changes, e.g., in the case of 800 km smoothing, annual amplitudes are reduced by about 25–40%, while annual phases are shifted by up to 10°. With these effects restored, GRACE-estimated water storage changes are consistently larger than model estimates, indicating that the land surface model appears to underestimate terrestrial water storage change. Our analysis based on simulation suggests that normalized attenuation effects (from Gaussian smoothing) on seasonal water storage change are relatively insensitive to the magnitude of the true signal. This study provides a numerical approach that can be used to restore seasonal water storage change in the basins from spatially smoothed GRACE data.

Keywords

GRACE Spatial smoothing Water storage estimation Seasonal variations Attenuation effect 

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Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • J. L. Chen
    • 1
  • C. R. Wilson
    • 2
  • J. S. Famiglietti
    • 3
  • Matt Rodell
    • 4
  1. 1.Center for Space ResearchUniversity of Texas at AustinAustinUSA
  2. 2.Department of Geological SciencesUniversity of Texas at AustinAustinUSA
  3. 3.Department of Earth System ScienceUniversity of CaliforniaIrvineUSA
  4. 4.Hydrological Sciences Branch, Code 614.3NASA Goddard Space Flight CenterGreenbeltUSA

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