Interpretation of Level 2 GOCE SGG data over limited geographical regions: a case study for Greece
19/09/2016 | 16:45 | Session 1: Current and future satellite gravity missions
Author(s): Christos Moukoulis and Dimitrios Tsoulis
Christos Moukoulis and Dimitrios Tsoulis
One of the main goals of the GOCE satellite mission was to improve the understanding of the Earth’s interior structure. The second-order derivatives of the Earth's gravity potential are particularly sensitive to the density and the geometry of the Earth’s inner structure. As our planet’s interior consists of layers with varying density and geometry, their contribution to the measured gravity gradient signal at satellite altitude, varies. In this paper, we isolate the gravity gradient radial component Vr of the various layers (crust, lithosphere, mantle and core) in order to investigate the corresponding gravity effects and their variations to the measured gradiometric signal. The used test area is the region surrounding Greece.
For our modeling purposes we approximate each layer as a spherical shell with known density and width. In this way, we can calculate the gradient radial component of each layer and compare it directly with the corresponding one from GOCE observed at a mean satellite altitude (250km). LITHO 1.0 global model of crust and lithosphere was used for the numerical data concerning the layers’ density and thickness. A GOCE gradient grid at mean satellite altitude was created by the projection of two years (2012-2013) of GOCE gradients data (EGG_NOM_2) to a mean sphere. These data where processed with a Butterworth filter inside the Measurement Bandwidth (5mHz – 0.05Hz) while their long wavelength signal was replaced with the corresponding part of a combined GOCE-GRACE geopotential model (GOGRA04S). The final outcome of this investigation is the correlation between the form, density and location of the individual layers with the gradiometric signal.