The goal of the proposed research is to enhance our understanding of the maintenance and time variations of the earth's magnetic field. The PI will focus on the dynamical balances and fundamental physics of the fluid motion and dynamo action for a model of buoyancy driven flow in a rotating self- gravitating, spherical shell. He will more specifically look at the time dependence of the flow when the laminar drifting thermal Rossby waves become unstable and at the effects of inhomogeneous lateral temperature boundary conditions at the core-mantle boundary. He will solve the nonlinear governing equations for continuity, momentum, temperature and magnetic field as a function of time using expansions in terms spherical harmonics and radial functions. The resulting solutions will be subjected to time- series analysis and the energy transfer mechanisms between mean and fluctuating, poloidal and toroidal fields will be determined. This work is expected to expand our understanding of the time dependence of the geodynamo and of the typical response of dynamos to lateral temperature variations at the core-mantle boundary.
