Geomagnetic Reversals in a Simple Geodynamo Model

A simple finite-dimensional geodynamo model, obtained from the equations of the mean field electrodynamics and reproducing the phenomenon of geomagnetic reversals, is proposed. It has been indicated that the reversal scale obtained in the scope of this model is rather close to the observed scale in its properties. The reversal mechanism is related to the alpha-effect fluctuations. It is not necessary to substantially change the hydrodynamic parameters of the problem so that a reversal originates in the scope of such a model, but it is only sufficient to take the alpha-effect fluctuations into account. If the rms deviation of fluctuations accounts for 10% of the average alpha value, a fluctuation of two-three standard deviations is sufficient for the origination of a reversal, which quite agrees with the concept that reversals are rather rare phenomena. Another factor resulting in the regime with reversals is that the model can generate magnetic fields with different behaviors in different regions of the parametric space in linear mode: monotonically increasing fields and fields increasing with oscillations. DOI: 10.1134/S0016793212020144