Mass motion in the Earth's core and mantle and their influence on polar motion

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Mass motion is the Earth¿s interior cause variations of polar motion and the gravity field. In this project, geophysical phenomena connected with the Earth core and mantle will be investigated, in particular for the decadal and subdecadal time scale ¿ a scale range, which is important for the objectives of the DFG Research Unit. The objectives of this project are (i) an improved modeling of core-mantle coupling and inner-core motions, to better understand the applied geophysical processes and to solve the present discrepancies between predicted and observed values of polar-motion variations, and (ii) to check whether the density variations and/or mass redistributions accompanying these processes are large enough to be detectable in the gravity field. A uniform model of various coupling mechanisms requires a uniform model of the coremantle transition zone. Existing models of this zone and the processes in the overlying mantle should be extended to output the polar motion and gravity quantities associated with resulting mass and density distributions and to determine their long-term changes.