Inferring parameters of the geodynamo from temporal reversal characteristics

One of the most prominent features of Earth's magnetic field reversals is their asymmetric shape which includes a slow decay of the initial dipole and a fast recreation of the reversed dipole. This relaxation-oscillation-like behaviour can result from a simple mean-field dynamo model in its highly supercritical regime. The same model can also explain the deviation of paleomagnetic reversal sequences from Poisson statistics, as well as the stochastic resonance phenomenon with the Milankovitch cycle of the Earth's orbit eccentricity. Encouraged by this agreement, we utilize those three temporal reversal characteristics to constrain the most essential parameters of the geodynamo, among them the effective (turbulent) magnetic diffusivity, the degree of supercriticality, and the relative strength of the periodic forcing. Using a downhill simplex method we obtain an optimized dynamo model that yields reversal characteristics which are in surprising correspondence with paleomagnetic data.