Tackling mass redistribution phenomena by time-dependent GRACE- and terrestrial gravity observations

Superconducting Gravimetry

“…Weise et al (2009), in a similar study, did not use the EOF technique, preferring to compare solutions at each station. Recently, two rather similar papers by Weise et al (2012) and Abe et al (2012) more or less came to the same conclusions, and so all studies agree on the strong common seasonal variations that are seen at the same level by the ground and GRACE data. Crossley et al (2012) did not correct for local hydrology, but still found a 79% agreement (Figure 41) between the first EOF mode from seven GGP stations (1s error of 1.0 mGal) and the improved GRACE satellite solutions (1s error of 1.5 mGal) from the GRGS/CNES group (Bruinsma et al, 2010).…”

“…This hydrologic seasonal signal in Europe of a few mGal according to the stations was the basis of recent studies that attempt to correlate ground and satellite gravity data Neumeyer et al, 2006;Weise et al, 2012). Even some variability in the seasonal component is visible in gravity; for instance, the drought impact in Europe during the summer of 2003 was well captured in some European SGs (Andersen and Hinderer, 2005;Hinderer et al, 2006).…”

Comment on: ‘The quest for a consistent signal in ground and GRACE gravity time-series’, by Michel Van Camp, Olivier de Viron, Laurent Metivier, Bruno Meurers and Olivier Francis

“…Several studies (e.g. Weise et al 2012) have shown that for some stations such as MO, ST and VI, the local hydrology effect is quite large and with a reversed sign, compared to a surface station, that consequently can dominate the regional part.…”

“…those using empirical orthogonal function (EOF) analysis: Neumeyer et al (2008), Crossley et al (2012), Abe et al (2012) and Weise et al (2012). In these papers, comparisons are made using the EOF decomposition of GRACE satellite gravity fields (computed as if at the Earth's surface), surface gravity as measured by a sparse network of superconducting gravimeters (SGs) that are part of the global geodynamics project (GGP) and global hydrology models.…”

Mass distribution and mass transport in the Earth system

“…They conclude that the GIA contribution dominates the secular GC motion. Weise et al (2012) employ the data of the -relatively sparsenetwork of superconducting gravimeters (SG) of the 'Global Geodynamics Project' (GGP) in order to validate GRACE data. However, they show that local hydrological effects in the SG observations, station stability of the SG sites with respect to vertical deformations, and filtering of the GRACE spherical harmonic models are all of serious concern for this kind of comparison.…”