Probing the deep Earth interior by a synergistic use of magnetic and gravity fields, and Earth's rotation

In order to understand the processes involved in the deep interior of the Earth and explaining its evolution, in particular the dynamics of the Earths fluid iron-rich outer core, only indirect satellite and ground observations are available. They each provide invaluable information about the core flow but are incomplete on their own. This is the case of (1) the magnetic field, which can be used to infer the motions of the fluid at the top of the core on decadal and sub-decadal time scales, (2) the gravity field variations, which reflect changes in the mass distribution within the Earth, and (3) the Earth's rotation changes (or variations in the length of the day). These variations are occurring at multi-annual timescales and largely related to the core fluid motions. Earth's rotation variations are induced through exchange of angular momentum between the core and the mantle at the core-mantle boundary. We are particularly interested by the 6 and 8-year variations. They are presented together with the main activities proposed in the frame of the GRACEFUL ERC project, which aims at combining all information from observation as well as modelling the core flow in a completely coupled core and mantle system.