Abstract
The question of what exactly happens with the geodynamo process during the reversal of a geomagnetic field is studied in a simple geodynamo model. The geodynamo action is described by the so called dynamo number characterizing the joint action of the main drivers of the geomagnetic field, i.e., the differential rotation and mirror–asymmetric convection. In mirror-asymmetric convection, for instance, in the northern hemisphere, there are more right vortices than left vortices, whereas in the southern hemisphere, there are more left vortices than right vortices. The effect of the magnetic field on the flow is described by the suppression of the mirror asymmetry: due to this suppression, e.g., in the northern hemisphere, the excess of right vortices over left vortices decreases. It is also assumed that due to this suppression, the mirror asymmetry can change its sign; i.e., the number of left vortices in the northern hemisphere can become larger than the number of right vortices. Correspondingly, the dynamo number can also change its sign. It is shown that the short-term changes of the sign of the dynamo number are responsible for the very short time span accommodating the reversal, when compared to the interval between the reversals.
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Berhanu, M., Monchaux, R., Fauve, S., Mordant, N., Pétrélis, F., Chiffaudel, A., Daviaud, F., Dubrulle, B., Marié, L., Ravelet, F., Bourgoin, M., Odier, Ph., Pinton, J.-F., and Volk, R., Magnetic field reversals in an experimental turbulent dynamo, Europhys. Lett., 2007, vol. 77, no. 5, p. 59001.
Kalashnikov, I.Yu., Sokoloff, D.D., and Chechetkin, V.M., Statistics of the geomagnetic dipole reversals based on paleomagnetic observations and simple geodynamo models, Izv., Phys. Solid Earth, 2015, vol. 51, no. 3, pp. 383–391.
Olson, P.L., Christensen, U.R., and Driscoll, P.E., From superchrons to secular variation: a broadband dynamo frequency spectrum for the geomagnetic dipole, Earth Planet. Sci. Lett., 2012a, vol. 319, pp. 75–82.
Olson, P.L., Glatzmaier, G.A., and Coe, R.S., Complex polarity reversals in a geodynamo model, Earth Planet. Sci. Lett., 2012b, vols. 319–320, pp. 75–82.
Parker, E.N., Hydromagnetic dynamo models, Astrophys. J., 1955, vol. 122, pp. 293–314.
Petrova, G.N., Nechaeva, T.B., and Pospelova, G.A., Kharakternye izmeneniya geomagnitnogo polya v proshlom (Characteristic Variations of Geomagnetic Field in the Past), Moscow: Nauka, 1992.
Reshetnyak, M.Yu. and Pavlov, V.E., Evolution of the dipole geomagnetic fField. Observations and Models, Geomagn. Aeron., 2016, vol. 56, no. 1, pp. 110–124.
Sobko, G.S., Zadkov, V.N., Sokoloff, D.D., and Trukhin, V.I., Geomagnetic reversals in a simple geodynamo model, Geomagn. Aeron., 2012, vol. 52, no. 2, pp. 254–260.
Sorriso-Valvo, L., Stefani, F., Carbone, V., Nigro, G., Leperti, F., Vecchio, A., and Veltri, P., A statistical analysis of polarity reversals of the geomagnetic field, Phys. Earth Planet Inter., 2007, vol. 164, nos. 3–4, pp. 197–207.
Valet, J.-P., Meynadier, L., and Guyodo, Y., Geomagnetic dipole strength and reversal rate over the past two million years, Nature, 2005, vol. 435, pp. 802–805.
Zeldovich, Ya.B., Ruzmaikin, A.A., and Sokoloff, D.D., Magnetic Fields in Astrophysics, New York: Gordon and Breach, 1983.
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Original Russian Text © E.V. Yushkov, D.D. Sokoloff, 2018, published in Fizika Zemli, 2018, No. 4.
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Yushkov, E.V., Sokoloff, D.D. Geomagnetic Reversals and Dynamo Bursts in a Simple Geodynamo Model. Izv., Phys. Solid Earth 54, 652–657 (2018). https://doi.org/10.1134/S1069351318040122
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DOI: https://doi.org/10.1134/S1069351318040122