Living Planet   


GOCE Gravity Field Processing

Dr Gernot Plank(1)

(1) Graz University of Technology, Steyrergasse 30, 8010 GRAZ, Austria


The dedicated satellite gravity mission, the first Core Mission of ESA's Living Planet Programme, strives for a high-accuracy, high-resolution global model of the Earth's gravity field. GOCE is based on a sensor fusion concept: satellite-to-satellite tracking in the high-low mode (hl-SST) using GPS, plus on-board satellite gravity gradiometry (SGG). The recovery of a full set of gravity field parameters (spherical harmonic coefficients) from these complementary data is a huge numerical and computational task. Therefore, parallel computing strategies have to be applied, which solve the fully occupied normal equation systems rigorously. The large matrices involved (e.g. 30 GB storage requirement for a system complete up to degree/order 300) have to be distributed over a Beowulf cluster. This distributed matrix has to be set up (each observation holds information which reflects onto the whole normal equations) and afterwards the system is solved to deliver the unknowns (harmonic coefficients) and the corresponding full variance - covariance information. Several numerical solution strategies and their combination for an optimum exploitation of the data are presented, assessed and compared both theoretically and on the basis of a realistic-as-possible numerical simulation, regarding the accuracy of the results as well as the computational effort. Special concern is given to the correct treatment of the coloured noise characteristics of the gradiometer as well as to the benefits which are achieved from the data combination of the SGG and hl-SST component.


Workshop presentation

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