Local Ensemble Transform Kalman Filtering Implemented on 2D and 3D Dynamo Flows

The behavior of the Earth's magnetic field and the influence of the core dynamics has been investigated in recent years through experiments and numerical models. At the University of Maryland, the geodynamo is replicated by experimental studies of the three-meter spherical Couette device filled with liquid sodium driven by two independently rotating concentric shells, an applied approximately dipole magnetic field, and dynamo action. These experiments incorporate high velocity flows in order to recreate the turbulence of convection-driven flows in the Earth. Collaborators at ISTerre have created the numerical code XSHELLS which features finite difference methods in the radial direction and pseudospectral spherical harmonic transforms for the angular directions. Highly turbulent flows are unfeasible to resolve limiting the abilities of purely numerical models. Experiments can produce highly turbulent flows but measurements can be intrusive. Our goal is to synchronize the outputs from the numerical code with the experimental magnetic boundary data to get an idea of the unknown velocity field. We present our preliminary studies of observation system simulation experiments (OSSEs) using a kinematic 2D dynamo model and the full 3D model. This research provides an avenue for making predictive models of the Earth's magnetic field. We gratefully acknowledge the support of NSF Grant No. EAR1417148 & DGE1322106.