The main goal of the GOCE mission is to determine the Earth’s stationary gravity field with unprecedented accuracy and resolution. Applications are expected in the area of marine geoid determination, a better understanding of the Earth’s interior, global height datum unification and the estimation of mass and thickness of polar ice sheets. To do so, the nominal mission lifetime is about two years with originally two measurement phases of six months and a hibernation phase of 5 months. However, due to the currently low solar activity and the lower than expected effect of drag on GOCE a hibernation phase is not necessary and probably GOCE can stay at one mean altitude for the entire mission lifetime. This opens the innovative possibility to study the aspect to study the Earth’s time-varying gravity field in the GOCE data.
The idea is that on the one hand the GOCE data may add additional information to what GRACE observes because GOCE is in a lower orbit than GRACE and the GOCE ground track pattern is regular instead of irregular for GRACE. The combination of GOCE and GRACE data may stabilize the GRACE only solution and may lead to a reduction of the well-known “stripes” in the GRACE solution. On the other hand, it appears that the GOCE gradiometer provides very accurate gravity gradient information, which may allow detecting large earthquakes. Whereas GRACE and terrestrial gravity data provide mostly 1D information on the gravity field, the GOCE gravity gradients provide 3D information, which may yield improved geophysical understanding.
The overall objective of the study is to investigate and explore at feasibility level the potential of GOCE data in the context of the Earth’s time-variable gravity field. In particular:
regional gravity field solutions will be computed for Greenland from a combination of GRACE and GOCE data;
- it is studied whether the signal of large earthquakes, such as the Chile February 2010 earthquake, are detectable with GOCE.