50. Comparison of Various Topographic-Isostatic Effects in Terms of Smoothing Gradiometric Observations

The main intention of the contribution is the computation and the comparison of five different topographic-isostatic effects and the analysis of the influence on all components of the disturbing gravity tensor. Based on the five different isostatic models, the topographic-isostatic effects are generated and their influence is analyzed for a GOCE-like satellite orbit. In particular the models of Airy-Heiskanen (A-H) and Pratt-Hayford (P-H), the combination of the Airy-Heiskanen model (land area) and the Pratt-Hayford model (ocean area) and the first (H1) and the second (H2) condensation model of Helmert, are considered. As it has been widely known, the reduction of the topographic-isostatic effect can significantly smooth the gravity signal, especially in or above the mountains. The benefit of this natural phenomenon is appreciated by the geodetic and geophysical community. Geodesists use the smoothed data, e.g. the refined Bouguer gravity anomalies, for interpolation and block-mean value computation, while geophysicists analyze the anomalous density distribution. A similar smoothing effect and advantageous use can also be expected in case of the gravity tensor components. A possibility to use the smoothing of measured satellite gradiometric data for regularization of the gradiometric inverse problem is discussed. The results can be applied on satellite gradiometry data in general; of course the primary interest is the application on the expected data of the ESA gradiometric mission GOCE.