Synchrony between dipole and quadrupole during magnetic field reversals and excursions

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In contrast to reversals, excursions of the geomagnetic field can occur at lower convection intensities in the Earth’s core. Since in such geodynamo regimes the behavior of the magnetic field is still quasi regular, a reduction of the dipole field during an excursion may indicate a global failure of the dynamo process. As a consequence, it is possible that during the excursion, not only the dipole component, but also the higher harmonics of the field decrease. This hypothesis is tested in a three-dimensional (3D) dynamo model.

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作者简介

M. Reshetnyak

Schmidt Institute of Physics of the Earth, Russian Academy of Sciences; Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences

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Email: m.reshetnyak@gmail.com
俄罗斯联邦, Moscow; Moscow

参考

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2. Fig. 1. Dependence on time t of the angle of deviation of the axial dipole from the geographic axis (a), the amplitude of the axial dipole (b), kinetic Ek (c) and magnetic Em (d) energies, and the axisymmetric quadrupole (e) for Ra = 4 10– 5. The most striking excursions are marked with numbers.

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3. Fig. 2. Dependence on time t of the angle of deviation of the axial dipole from the geographic axis (a), the amplitude of the axial dipole (b), kinetic Ek (c) and magnetic Em (d) energies, and the axisymmetric quadrupole (e) for Ra = 5 10- 5. The numbers indicate the most striking inversions.

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4. Fig. 3. Dependence on time t of the axial dipole (a), (c), (e) and quadrupole (b), (d), (f) during inversions (1, 2, 3) in Fig. 2 respectively on an enlarged scale.

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