Multidisciplinary studies of deep Earth: From geodynamo to geodesy

It has long been known that Earth possesses a magnetic field of internal origin (geomagnetic field). This field is generated and maintained by vigorous convection in the Earth's fluid outer core (geodynamo theory). Recent success in numerical geodynamo modeling has made it possible to analyze the details of dynamical processes in the core and its forcing on solid Earth, such as electromagnetic torque driving the solid inner core rotating relative to the solid mantle, and non-hydrostatic pressure acting on the core-mantle boundary. In parallel, observations on global surface geophysical processes, such as Earth's gravity field and large-scale surface deformation, are reaching to unprecedented level in both accuracy and in long-time measurement coverage, as evidenced by recent and up-coming satellite missions.These advances in both science and technology may provide new opportunities in multi-disciplinary studies on interactions between the solid Earth and the liquid outer core. Two research fields are in particular promising: the influence of relative rotation of the inner core on global gravity field variation, and the effect of non-hydrostatic pressure on deformation of the mantle. Studies of these problems could help us not only on identifying responses of the solid Earth to the forces from the fluid outer core, but also on providing further insights on core dynamical processes from non-geomagnetic, surface observations.