Simple stochastic model for geomagnetic excursions and reversals reproduces the temporal asymmetry of the axial dipole moment

Abstract

The geodynamo, the process that produces and controls the evolution of the Earth’s magnetic field, is still not fully understood. Despite the success of current numerical geodynamo models in reproducing some geomagnetic observations, their high complexity and computational requirements hinder their use for certain studies. Here, we present a simple model based on random fluctuations that is able to reproduce the temporal asymmetry of the dipolar strength of the field observed during polarity reversals. This behavior arises due to the existence of two parts of the model that are energetically unbalanced, imposing a preferred direction of energy transfer, and we propose that the same mechanism would be the cause of the temporal asymmetry of the geodynamo.