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Gravity gradients from mean sea level – data for validation and downward continuation of GOCE gravity fields

Wolfgang Bosch(1)

(1) DGFI, Alfons-Goppel-Strasse 11, 80539 München, Germany

Abstract

Combining Laplace Differential Equation and Bruns formula yields to a well known relationship between geometry and gravity: Gravity gradients of an equipotential surface are related to the mean curvature. It is shown that – in the present context – the deviation between geoid and mean sea level, known as sea surface topography, can be neglected and that the mean curvature of the geoid can be approximated by the mean curvature of the mean sea level. Consequently, models of mean sea surface heights are used to derive gravity gradients. As the spatial resolution of GOCE-only gravity fields will be restricted by band limited spherical harmonics (developed up to degree and order 250) the gravity gradients are smoothed correspondingly and – as long as GOCE models are not yet available – compared with the most recent gravity field from GRACE. Gravity gradients from mean sea level are gravity data on the Earth surface – as close as possible to the gravitating masses. Therefore this data should allow to strengthen the downward continuation of GOCE observation. It is investigated to what extend the normal equations of satellite-only gravity fields are stabilized by gravity gradients derived from mean sea level.

 

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