Climate‐driven deformation of the solid Earth from GRACE and GPS

Davis, J. L.; Elósegui, P.; Mitrovica, J. X.; Tamisiea, M. E.

doi:10.1029/2004gl021435

Cited by 190 publications

(165 citation statements)

References 13 publications

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“…Half or a bit more of the observed annual signal is driven by seasonal variations in environmental surface loads (see, for example, Dong et al 2002;Davis et al 2004;Blewitt et al 2001;Kusche and Schrama 2005;Horwath et al 2010;Wu et al 2006;van Dam et al 2007, etc.). Thermal deformation of the GPS monuments and the bedrock to which they are attached probably also contribute an annual signal (Dong et al 2002;Yan et al 2009).…”

Section: Seasonal Signalsmentioning

confidence: 99%

Nontidal ocean loading: amplitudes and potential effects in GPS height time series

Dam

Collilieux

Wuite

et al. 2012

J Geod

107

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Ocean bottom pressure (OBP) changes are caused by a redistribution of the ocean's internal mass that are driven by atmospheric circulation, a change in the mass entering or leaving the ocean, and/or a change in the integrated atmospheric mass over the ocean areas. The only previous global analysis investigating the magnitude of OBP surface displacements used older OBP data sets (van Dam et al. in J Geophys Res 129:507-517, 1997). Since then significant improvements in meteorological forcing models used to predict OBP have been made, augmented by observations from satellite altimetry and expendable bathythermograph profiles. Using more recent OBP estimates from the Estimating the Circulation and Climate of the Ocean (ECCO) project, we reassess the amplitude of the predicted effect of OBP on the height coordinate time series from a global distribution of GPS stations. OBP-predicted loading effects display an RMS scatter in the height of between 0.2 and 3.7 mm, larger than previously reported but still much smaller (by a factor of 2) than the scatter observed due to atmospheric pressure loading. Given the improvement in GPS hardware and data analysis techniques, the OBP signal is similar to the precision of weekly GPS height coordinates. We estimate the effect of OBP on GPS height coordinate time series using the MIT reprocessed solution, mi1. When we compare the predicted OBP height time series with mi1, we find that the scatter is reduced over all stations by 0.1 mm on average with reductions as high as 0.7 mm at some stations. More importantly we are able to reduce the scatter on 65 % of the stations investigated. The annual component of the OBP signal is responsible for 80 % of the reduction in scatter on average. We find that stations located close to semi-enclosed bays or seas are affected by OBP loading to a greater extent than other stations.

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Section: Seasonal Signalsmentioning

confidence: 99%

Nontidal ocean loading: amplitudes and potential effects in GPS height time series

Dam

Collilieux

Wuite

et al. 2012

J Geod

107

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“…Davis et al (2004) applied an F-test (Lunneborg 1994) to determine whether fitting for an annual variation yielded a significant decrease in the scatter of the coefficient time-series, and only chose the Stokes coefficients that passed the 99.95% level of significance, which included only 72 degree/order pairs under spherical harmonic degree 10. This technique can significantly reduce the 'striping' noise in GRACE data.…”

Section: Introductionmentioning

confidence: 99%

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

Chen

Wilson

Famiglietti

et al. 2006

J Geod

103

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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 basinscale 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.

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“…More recently, promising results of geocenter motion estimates have been reported for joint inversions of a wide number of di erent observations, i.e. satellite altimetry over the oceans, GPS permanent station observations, in-situ ocean bottom pressure observations, GRACE time-variable gravity elds (Davis et al, 2004;Jansen et al, 2009;Rietbroek et al, 2012). Partially augmented by information from geophysical models, those joint inversions provide geocenter motion estimates that are presumably more robust and less noisy than results from a single observing system alone.…”

Section: Introductionmentioning

confidence: 99%

Global Eustatic Sea-Level Variations for the Approximation of Geocenter Motion from Grace

Bergmann-Wolf

Zhang

Dobslaw

2014

Journal of Geodetic Science

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Global degree-1 coe cients are derived by means of the method by Swenson et al. (2008) from a model of ocean mass variability and RL05 GRACE monthly mean gravity elds. Since an ocean model consistent with the GRACE GSM elds is required to solely include eustatic sea-level variability which can be safely assumed to be globally homogeneous, it can be empirically derived from GRACE as well, thereby allowing to approximate geocenter motion entirely out of the GRACE monthly mean gravity elds. Numerical experiments with a decade-long model time-series reveal that the methodology is generally robust both with respect to potential errors in the atmospheric part of AOD1B and assumptions on global degree-1 coe cients for the eustatic sea-level model. Good correspondence of the GRACE RL05-based geocenter estimates with independent results let us conclude that this approximate method for the geocenter motion is well suited to be used for oceanographic and hydrological applications of regional mass variability from GRACE, where otherwise an important part of the signal would be omitted.

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Climate‐driven deformation of the solid Earth from GRACE and GPS

Cited by 190 publications

References 13 publications

Nontidal ocean loading: amplitudes and potential effects in GPS height time series

Nontidal ocean loading: amplitudes and potential effects in GPS height time series

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

Global Eustatic Sea-Level Variations for the Approximation of Geocenter Motion from Grace

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