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Recovery of the gravity field signal due to a low viscosity crustal layer in GIA models from simulated GOCE data

Hugo Schotman(1), Radboud Koop(2) , Bert Vermeersen(3) , and Pieter Visser(3)

(1) DEOS, Delft University of Technology & SRON, Kluyverweg 1, 2629 HS Delft, Netherlands
(2) SRON National Institute for Space Research, Sorbonnelaan 2, 3584 CA UTRECHT, Netherlands
(3) DEOS, Delft University of Technology, Kluyverweg 1, 2629 HS Delft, Netherlands

Abstract

We model the glacial isostatic adjustment (GIA) process using a semi-analytical normal mode technique (Vermeersen & Sabadini 1997) and a pseudo-spectral sea level code (Mitrovica & Peltier 1991) to compute the response of a model Earth to a sea and ice load history. The results of these computations are 3-D displacements, free-air gravity anomalies and geoid heights.

In previous studies (Vermeersen (2003), van der Wal et al. (2003), Schotman et al. (2003)), we have investigated the influence on the high resolution gravity field signal of a ductile, low viscosity layer in the lower crust of the Earth, and the use of different sea and ice load histories. We have compared the results with the expected GOCE performance.

In this study, we use this forward model in the simulation of GOCE satellite gravity gradient (SSG) measurements. First, reference SSG measurements are simulated by an a priori gravity field model. Second, SSG measurements are simulated by extending the a priori gravity field model with the gravity signal due to a ductile crustal layer. The differences between these measurements or residues then show the effect of such a layer on GOCE measurements.

In the next step, the gravity field model is further extended by additional signals due to for example topography, and time-variable signals as the atmosphere. We recover the gravity field signal due to the ductile crustal layer from these measurements and estimate the inversion or aliasing error.

Our current Earth model can handle variations in the radial direction only. To make full use of the spatial high resolution capabilities of GOCE, we are developing a regional finite element model to include lateral heterogeneities. To study the effect of these results on GOCE measurements, we consider investigating the use of a non-global inversion.

 

Full paper

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry

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