Mantle plumes and the geoid: Plume dynamics and their signature in the GRACE derived gravity field

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We will systematically study the relation between plumes and the geoid or gravity and dynamic topography to identify plumes and resolve their upper/lower mantle structure, their dynamics, their (laterally varying) rheology, and their origin. In up to two case studies surface effects of plumes will be discriminated from deep effects and regional seismic tomography anomalies will be used to fit the residual gravity field and the dynamic topography. In a more general approach synthetic plumes, the observed gravity field and the topography will be analysed and characterized by a spatially and scale dependent wavelet analysis. This will allow a regional space and frequency characterization of plumes, their effects to the gravitational field as well as their specific influences on topography. In consequence, it gives a representation of the admittance (spectral ratio of geoid to topography) in scale and space, i.e. the spatial evolution of the frequency properties of the admittance. By comparison with modelled field characteristics detection of plumes from the gravity field and a classification into different plume groups will be tried. High precision observations of the gravity potential and the geoid by CHAMP, GRACE will be needed to differentiate between different types of plumes. As a byproduct, the time dependence of the gravity field and dynamic topography of ultrafast power-law rheology plumes will be studied and compared to GRACE data.