ESA's gravity mission GOCE measures the Earth's mean gravitational field with unprecedented accuracy with a spatial resolution of 100 km or better. Comparing GOCE gravity gradients with gradients from geophysical modelling for the North-East Atlantic (NEA) margin shows that the spatial patterns are similar, but that the amplitudes differs. This indicates that even in well-surveyed areas, such as the NEA, GOCE data may contribute to improved modelling of the Earth's interior.
GOCE data may improve the understanding and modelling of the Earth’s interior and its dynamic processes, contributing to gain new insights into the geodynamics associated with the lithosphere, mantle composition and rheology, uplift and subduction processes. However, to achieve this challenging target, GOCE should be used in combination with additional data sources: e.g. magnetic, gravity and seismology in situ, airborne and satellite data sets. In the context of an ESA sponsored study, part of ESA’s Support to Science Element (STSE), DGFI collaborates with NGU (Norway) and TNO (The Netherlands). The overall objective of the study is to combine GOCE gravity gradients with heterogeneous other satellite gravity information to arrive at a combined set of gravity gradients complementing (near)-surface data sets and demonstrate their utility to complement additional data to enhance geophysical modelling and exploration.
In a first step, we compared the shape and amplitude of gravity gradients from a 3D lithosphere density model for the North-East Atlantic Margin with GOCE data. Gravity gradients in the north-oriented frame at GOCE altitude were used and EGM2008 to degree and order 10 was subtracted. The long wavelength signal of the original GOCE gradients is not well determined and was replaced by GOCO01S signal before rotation from the instrument frame to the northoriented frame. The model and GOCE gravity gradients show similar anomalies, although with different amplitudes (see Figure). The difference in orientation of the reference frames for the density model and GOCE has to be accounted for. The modeled density gradients have the orientation East-North-Up, whereas the GOCE gradients are oriented North-West-Up. In addition, geophysical modeling software normally uses a Cartesian coordinate system, whereas the GOCE data product is defined in a geographical system, which leads to a difference in azimuth between the two systems.