Collapse and Recovery of the Magnetic Field During Reversals

Abstract

The process of polarity reversal of a magnetic dipole is considered using the two-dimensional model of the mean-field with random α-effect. The correlation of the sequence of fluctuations of α and the evolution of a magnetic dipole is investigated. It was shown that during fluctuations, which subsequently lead to inversions of the magnetic field, the dynamo system can switch to the mode of frequent changes in the dipole polarity with a lowered magnetic field, as well as to the temporal damping mode. Since the characteristic decay and generation times are different, a temporary asymmetry of the magnetic field arises during the reversal: the time of reduction of the magnetic dipole is several times longer than its growth time. The asymmetry for the geomagnetic field over the last five inversions is 4 : 1, which is close to the simulation results.