Impact of GOCE on Lithospheric Modelling in Active Plate Margins
Hosse, Michael1; Pail, Roland1; Horwath, Martin1; Romanyuk, Tetjana2; Gutknecht, Ben3; Köther, Nils3
1TU Muenchen, Institute of Astronomical and Physical Geodesy, GERMANY; 2TU München, Institute of Astronomical and Physical Geodesy, GERMANY; 3Christian-Albrechts-Universitaet Kiel, Institute of Geosciences, Department of Geophysics, GERMANY
New gravity field data from GOCE provide new, high-accuracy and globally uniform information of the Earth’s gravity field. This new gravity field information has an impact especially in regions where the terrestrial data quality is poor, such as the active plate margin of the subduction zone in South America.
Comparison of global GOCE gravity models with terrestrial gravity data reveals that there are large systematic differences in South America, which can be attributed to a low data quality of the terrestrial data. Consequently, lithospheric models of the study region, which did not yet include GOCE, are affected with long to medium wavelength errors. In this case study area a combined gravity field model from GOCE, GRACE and ground data has been computed, which provides a new constraint for lithospheric modelling.
In a first step, the ground data (gravity anomalies and associated heights) have been validated against external information, such as global GOCE gravity models and ACE2 digital terrain model. In order to validate ground gravity satellite data, the high-frequency signal content (mainly contained in terrestrial data) has been be reduced consistently by a topographic-isostatic reduction.
The optimum combination of terrestrial gravity anomalies and GOCE gravity gradient data has been achieved by Least Squares Collocation, taking the full variance-covariance information of the gravity gradients into account. Therefore not only a combined regional gravity field model but also associated error information has been derived.
Finally, lithospheric density modelling applying the IGMAS+ software has been performed based on this new gravity field model, and the resulting density model has been compared to a model of the pre-GOCE area, thus evaluating the impact of GOCE to geophysical modelling of the lithosphere.