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A regional GOCE validation and combination experiment based on absolute gravity, deflections of the vertical and GPS/levelling data

Nina Lux(1) and Christian Voigt(2)

(1) Bundesamt für Kartographie und Geodäsie (BKG), Richard-Strauss-Allee 11, D-60598 Frankfurt, Germany
(2) Institut fuer Erdmessung(IfE) Universität Hannover, Schneiderberg 50, D-30167 Hannover, Germany

Abstract

Authors: N. Lux 1, C. Voigt 2, J. Ihde 1, H. Denker 2

Institutions: 1 Bundesamt für Kartographie und Geodäsie (BKG) Frankfurt, Germany; 2 Institut für Erdmessung (IfE) Universität Hannover, Germany

Within the framework of the GOCE-GRAND II project (GRavitationsfeldANalyse Deutschland), a regional GOCE validation and combination experiment is realized in Germany, where absolute gravity observations, deflections of the vertical and GPS/levelling data are employed as independent data sets. About 100 new absolute gravity stations are planned as spot-checks of the existing gravity data base, aiming at the validation and detection of possibly existing offsets or other systematic errors in the existing gravity data base that is used for geoid modelling. For this purpose, the new and recently developed portable absolute gravimeter A 10 is used, which is the only absolute gravity instrument suitable for field operation. In addition, deflections of the vertical are observed with a transportable digital zenith camera (TZK2-D) in profiles, traversing through all nearby GPS/levelling stations and thus allowing a cross validation of both data sets. After filtering the surface data to remove high frequencies not included in the GOCE models, all terrestrial data sets are employed in the validation of the global GOCE geopotential models.

Besides the validation of the GOCE products, the second major issue of the project is the combination of the (revised) terrestrial gravity field data with the global models from the GOCE mission in order to compute geoid or quasigeoid models which provide the complete spectrum (all wavelengths) with an accuracy at the centimeter level. The combination shall be carried out in a remove-restore procedure using a spectral combination technique (IfE) and the method of point mass modelling (BKG). The combination solutions will again be evaluated by independent data, i.e., GPS/levelling and deflection of the vertical data.

The paper will describe the project background and aims. Then the field experiences obtained so far with the absolute gravimeter A 10 and the transportable digital zenith camera TZK2-D including instrumental enhancements will be described. The accomplished part of the field campaigns will be documented and first results will be presented. An outlook will be given on further proceeding, which includes the determination of the geoid models from the combination of terrestrial and satellite gravity field models.

GOCE-GRAND II is supported under grant 03F0422A BMBF/DFG Research and Development Programme “Geotechnologien”.

 

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