HR: 0800h
AN: G31C-0812    [Abstracts]
TI: Issues in the Comparison of Ground Gravity with GRACE Data
AU: * Crossley, D J
EM: crossley@eas.slu.edu
AF: Saint Louis University, Department of Earth and Atmospheric Sciences, 3507 Laclede Ave., St. Louis, MO 63049 United States
AU: Hinderer, J
EM: jacques.hinderer@eost.u-strasbg.fr
AF: EOST / IPG Strasbourg, 5, Rue Descartes, Strasbourg, 67084 France
AU: Neumeyer, J
EM: neum@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg A17, Potsdam, D-14473 Germany
AB: Agreement in general has previously been established between superconducting gravimeter (SG) data of the Global Geodynamics Project, GRACE satellite data, and hydrology models of soil moisture for a region in central Europe. Nonetheless, there are several issues still to be resolved before one can be convinced of the robustness of the correlation. In this paper we extend the previous work (years 2000-2002) with the most recent SG and GRACE data available. From the point of view of ground gravity, our previous atmospheric corrections for the European stations were insufficient. Here we include a 3-D atmospheric model that incorporates data on vertical structure and that is known to contribute a seasonal component of about 1 microgal into the gravity residuals. We also discuss the use of GPS data to represent a vertical displacement of the surface that affects grounds measurements but is not seen by the satellite. Perhaps the most difficult and controversial aspect is how to incorporate local hydrology into the SG data reduction. The spatial averaging of many ground-based stations, although in principle equivalent to a satellite-derived smoothing of the hydrology, is clearly problematic when using only a handful of stations. We here discuss the role of local topographic and hydrological models, especially where there is mass above the station as in an underground installation, in the analysis of the SG data. Using Strasbourg (J9) as an example installation, we present the results of initial modeling that show the potential benefit of using a sub-array of gravity measurements around an SG station to solve the problem.
DE: 1214 Geopotential theory and determination
DE: 1219 Local gravity anomalies and crustal structure
DE: 1249 Tides--Earth
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting