Magnetic Field Variations in Geodynamo Models

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Abstract

An increase in the intensity of heat sources in the Earth’s core leads to a decrease in the intensity of the dipole magnetic field. The spatial spectrum of the magnetic field becomes multipole. The intensity of variations of the magnetic dipole and its deviations from the rotation axis increases. The dependence of the duration of magnetozones of constant polarity depends on the amplitude of the magnetic dipole according to a power law. The exponent of the power function can change by a factor of two depending on the dipole amplitude. Superchrons of the magnetic field correspond to high intensity of the magnetic dipole.

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About the authors

М. Yu. Reshetnyak

Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences

Author for correspondence.
Email: m.reshetnyak@gmail.com
Russian Federation, Moscow

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Supplementary files

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2. Fig. 1. Time-averaged dependence of the axisymmetric dipole amplitude, kinetic and magnetic energies on the Rayleigh number in the range Ra = (3 − 6) 104 with a step of 5 · 103.

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3. Fig. 2. Dependence of the mean-square deviation of the axisymmetric dipole, kinetic and magnetic energies on the Rayleigh number (upper figure) and of the normalised mean-square deviations of the axisymmetric dipole from the axis of rotation, kinetic and magnetic energies on the Rayleigh number (lower figure).

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4. Fig. 3. Dependence of the time-averaged deviation of the axisymmetric dipole from the axis of rotation and the standard deviation.

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5. Fig. 4. Dependence of the duration of the constant polarity zone τ on the axisymmetric dipole strength. The figure also shows approximations of some fragments of the curve by degree functions.

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