Simplified model for axial dipole moment of the geomagnetic field from Brownian fluctuations

The magnetic field of the Earth is generated in its core by the process called the geodynamo, which involves convection in the fluid and electrical conducting outer core. The evolution of this complex process is simulated by magnetohydrodynamic models, which provide the state of the core and the magnetic field at any point and any time of the simulation. Nevertheless, the complexity of these models implies a high computational cost. That is why conceptual simple models describing only the main mechanisms from a statistical perspective can also be useful.

In this work we present a conceptual model that reproduces the main features of the axial dipole moment (ADM) of the Earth magnetic field. It is based on the stochastic dynamics of two Brownian particles interacting with each other within a double-well potential. The obtained simulations are able to mimic the random temporal distribution of reversals and excursions and the asymmetric temporal evolution of ADM during reversals. The relation between the model features and the real mechanisms that lead to the observed behaviour is discussed.