Russian Journal of Earth Sciences Russian Journal of Earth Sciences Russian Journal of Earth Sciences 1681-1208 46900 ОРИГИНАЛЬНЫЕ СТАТЬИ ORIGINAL ARTICLES ОРИГИНАЛЬНЫЕ СТАТЬИ The mean-field dynamo model in geodynamo The mean-field dynamo model in geodynamo Reshetnyak M Yu Reshetnyak M Yu Schmidt United Institute of Physics of the Earth, Russian Academy of Sciences ru Schmidt United Institute of Physics of the Earth, Russian Academy of Sciences ru 14 2 1 7 10 11 2021 https://rjes.ru/en/nauka/article/46900/view

The 2D Parker's mean-field dynamo equations with a various distributions of the #x3B1;- and #x3C9;-effects are considered. We show that smooth profiles of #x3B1; and #x3C9; can produce dipole configuration of the magnetic field with the realistic magnetic energy spectrum. We emphasize that fluctuating #x3B1;-effect leads to increase of the magnetic energy at the small scales, breaking the dipole configuration of the field. The considered geostrophic profiles of #x3B1; and #x3C9; correspond to the small-scale polarwards/equatorwards travelling waves with the small dipole field contribution. The same result is observed for the dynamic form of the #x3B1;-quenching, where two branches of the weak and strong solution coexist.

The 2D Parker's mean-field dynamo equations with a various distributions of the #x3B1;- and #x3C9;-effects are considered. We show that smooth profiles of #x3B1; and #x3C9; can produce dipole configuration of the magnetic field with the realistic magnetic energy spectrum. We emphasize that fluctuating #x3B1;-effect leads to increase of the magnetic energy at the small scales, breaking the dipole configuration of the field. The considered geostrophic profiles of #x3B1; and #x3C9; correspond to the small-scale polarwards/equatorwards travelling waves with the small dipole field contribution. The same result is observed for the dynamic form of the #x3B1;-quenching, where two branches of the weak and strong solution coexist.

Earth's liquid core turbulence geodynamo Earth's liquid core turbulence geodynamo

Belvedere, A two-dimensional asymptotic solution for a dynamo wave in the light of the solar internal rotation, // Mon. Not. R. Astron. Soc., v. 315, 2000. Belvedere, A two-dimensional asymptotic solution for a dynamo wave in the light of the solar internal rotation, // Mon. Not. R. Astron. Soc., v. 315, 2000. Braginsky, Nearly axially symmetric model of the hydromagnetic dynamo of the Earth, I, Geomagn. Aeron., v. 15, 1975. Braginsky, Nearly axially symmetric model of the hydromagnetic dynamo of the Earth, I, Geomagn. Aeron., v. 15, 1975. Brandenburg, Astrophysical magnetic fields and nonlinear dynamo theory, // Phys. Rep., v. 417, 2005., doi: 10.1016/j.physrep.2005.06.005 Brandenburg, Astrophysical magnetic fields and nonlinear dynamo theory, // Phys. Rep., v. 417, 2005., doi: 10.1016/j.physrep.2005.06.005 Christensen, Numerical modeling of the geodynamo: a systematic parameter study, // Geophys. J. Int., v. 138, 1999. Christensen, Numerical modeling of the geodynamo: a systematic parameter study, // Geophys. J. Int., v. 138, 1999. Finlay, International Geomagnetic Reference Field: the eleventh generation, // Geophys. J. Int., v. 183, no. 3, 2010., doi: 10.1111/j.1365-246X.2010.04804.x Finlay, International Geomagnetic Reference Field: the eleventh generation, // Geophys. J. Int., v. 183, no. 3, 2010., doi: 10.1111/j.1365-246X.2010.04804.x Hejda, Nonlinearity in dynamo, // Geophys. Astrophys. Fluid Dynam., v. 104, no. 6, 1993., doi: 10.1080/03091929.2010.496365 Hejda, Nonlinearity in dynamo, // Geophys. Astrophys. Fluid Dynam., v. 104, no. 6, 1993., doi: 10.1080/03091929.2010.496365 Hoyng, Helicity fluctuations in mean field theory: an explanation for the variability of the solar cycle?, // Astron. Astrophys., v. 272, 1993. Hoyng, Helicity fluctuations in mean field theory: an explanation for the variability of the solar cycle?, // Astron. Astrophys., v. 272, 1993. Jones, Convection-driven geodynamo models, // Phil. Trans.~R.~Soc.~London, v. A358, 2000., doi: 10.1098/rsta.2000.0565 Jones, Convection-driven geodynamo models, // Phil. Trans.~R.~Soc.~London, v. A358, 2000., doi: 10.1098/rsta.2000.0565 Jouve, A solar mean field dynamo benchmark, // Astron. Astrophys., v. 483, 2008., doi: 10.1051/0004-6361:20078351 Jouve, A solar mean field dynamo benchmark, // Astron. Astrophys., v. 483, 2008., doi: 10.1051/0004-6361:20078351 Kleeorin, Magnitude of dynamo-generated magnetic field in solar-type convective zones, // Astronomy and Astrophysics, v. 297, 1995. Kleeorin, Magnitude of dynamo-generated magnetic field in solar-type convective zones, // Astronomy and Astrophysics, v. 297, 1995. Kraichnan, Two-dimensional turbulence, Rep. Prog. Phys., v. 43, 1980. Kraichnan, Two-dimensional turbulence, Rep. Prog. Phys., v. 43, 1980. Krause, Mean-Field Magnetohydrodynamics and Dynamo Theory, 1980. Krause, Mean-Field Magnetohydrodynamics and Dynamo Theory, 1980. Langel, The Main Field, Geomagnetism, edited by J. A. Jacobs, v. 1, 1987. Langel, The Main Field, Geomagnetism, edited by J. A. Jacobs, v. 1, 1987. Moss, Polar branches of stellar activity waves: dynamo models and observations, // Astronomy and Astrophysics, v. 531, 2011., doi: 10.1051/0004-6361/201015949 Moss, Polar branches of stellar activity waves: dynamo models and observations, // Astronomy and Astrophysics, v. 531, 2011., doi: 10.1051/0004-6361/201015949 Moss, Reversals of the solar dipole, // Astronomy and Astrophysics, v. 550, 2013., doi: 10.1051/0004-6361/201220766 Moss, Reversals of the solar dipole, // Astronomy and Astrophysics, v. 550, 2013., doi: 10.1051/0004-6361/201220766 Pedlosky, Geophysical Fluid Dynamics, 2nd ed., 1987. Pedlosky, Geophysical Fluid Dynamics, 2nd ed., 1987. Pouquet, Strong MHD helical turbulence and the nonlinear dynamo effect, // J. Fluid Mech., v. 77, 1976. Pouquet, Strong MHD helical turbulence and the nonlinear dynamo effect, // J. Fluid Mech., v. 77, 1976. Reshetnyak, Geomagnetic field intensity and suppression of helicity in the geodynamo, // Izvestiya, Physics of the Solid Earth, v. 39, no. 9, 2003. Reshetnyak, Geomagnetic field intensity and suppression of helicity in the geodynamo, // Izvestiya, Physics of the Solid Earth, v. 39, no. 9, 2003. Reshetnyak, Taylor cylinder and convection in a spherical shell, // Geomagn. Aeron., v. 50, no. 2, 2010., doi: 10.1134/S0016793210020143 Reshetnyak, Taylor cylinder and convection in a spherical shell, // Geomagn. Aeron., v. 50, no. 2, 2010., doi: 10.1134/S0016793210020143 Reshetnyak, Geostrophic balance and reversals of the geomagnetic field, // Russ. J. Earth Sci., v. 13, 2013., doi: 10.2205/2013ES000526 Reshetnyak, Geostrophic balance and reversals of the geomagnetic field, // Russ. J. Earth Sci., v. 13, 2013., doi: 10.2205/2013ES000526 Roberts, On the genesis of the Earth's magnetism, // Rep. Prog. Phys., v. 76, no. 9, 2013., doi: 10.1088/0034-4885/76/9/096801 Roberts, On the genesis of the Earth's magnetism, // Rep. Prog. Phys., v. 76, no. 9, 2013., doi: 10.1088/0034-4885/76/9/096801 Sobko, Geomagnetic reversals in a simple geodynamo model, // Geomagnetism and Aeronomy, v. 52, no. 2, 2012., doi: 10.1134/S0016793212020144 Sobko, Geomagnetic reversals in a simple geodynamo model, // Geomagnetism and Aeronomy, v. 52, no. 2, 2012., doi: 10.1134/S0016793212020144 Wicht, Inner-core conductivity in numerical dynamo simulations, // Phys. Earth Planet. Int., v. 132, 2002., doi: 10.1016/S0031-92010200078-X Wicht, Inner-core conductivity in numerical dynamo simulations, // Phys. Earth Planet. Int., v. 132, 2002., doi: 10.1016/S0031-92010200078-X Zeldovich, Magnetic Fields in Astrophysics, 1990. Zeldovich, Magnetic Fields in Astrophysics, 1990.