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Multi-resolution representation of the gravity field from a combination of GOCE and GRACE data

Michael Schmidt(1), C.K. Shum(2), Shin-Chan Han(2) and Juergen Kusche(3)

(1) DGFI, Alfons-Goppel-Strasse 11, 80539 Muenchen, Germany
(2) The Ohio State University, 275 Mendenhall, Columbus, OH 43210-1308, United States
(3) DEOS, Kluyverweg 1, 2600 GB Delft, Netherlands

Abstract

The GOCE mission will allow the determination of the Earth's static gravity field down to features less than 100km w.r.t. the spatial resolution. Traditionally in satellite gravity recovery problems the global gravity field of the Earth has been modeled as a spherical harmonic expansion. Recently, regional modeling techniques have been successfully applied to GRACE data and provide new insights in gravity field determination. In our approach a multi-resolution representation, i.e. the decomposition of the gravity field into constituents or levels of different spatial resolution, has been realized using spherical scaling functions and spherical wavelets.

The combination of GRACE and GOCE is a particular challenging area of research. A combined time-averaged mean field will benefit from GOCE gradiometry in the high degrees - the higher resolution levels in our approach - and GRACE POD and K-band tracking in the lower degrees or resolution levels, with a time-variable parameterization of the lower degrees absorbing time-variable signals. In our concept, the time-variable representation of the lower resolution levels, i.e. one-dimensional series expansions for the corresponding scaling and wavelet coefficients, will be estimated jointly with the static higher resolution levels that benefit from GOCE, leading to optimal estimates for all field constituents.

 

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