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Magnetic fields generated by thermally, chemically, and thermochemically driven dynamos

Ján Šimkanin*

Juraj Kyselica†

  • *Contact author: j.simkanin@hzdr.de
  • †Contact author: kyselica@ig.cas.cz
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Phys. Rev. Fluids 10, 103705 – Published 27 October, 2025

DOI: https://doi.org/10.1103/b7ym-jxrf

Abstract

Solidification processes at the boundary between the Earth's inner and outer core are the primary source of buoyancy forces that drive convection and Geodynamo in the outer core. This study aims to numerically investigate the impact of different buoyancy sources on convection within the Earth's core and the resulting magnetic field. We analyze three models: thermally driven, chemically driven, and thermochemically driven dynamos. The results confirm that both the magnetic field and the convective velocity field depend on the sources of buoyancy. Additionally, dipole polarity reversals and the super-rotation of the Earth's inner core are influenced by different buoyancy sources. As the Ekman number decreases, this dependence weakens.

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References (47)

  1. K. Moffatt and E. Dormy, Self-Exciting Fluid Dynamos (Cambridge University Press, Cambridge, UK, 2019).
  2. G. A. Glatzmaier and P. H. Roberts, Simulating the geodynamo, Contemp. Phys. 38, 269 (1997).
  3. U. R. Christensen and J. Wicht, Numerical dynamo simulations, in Treatise on Geophysics, edited by G. Schubert (Elsevier, Amsterdam, 2007), Vol. 8, pp. 245–282.
  4. C. A. Jones, Planetary magnetic fields and fluid dynamos, Annu. Rev. Fluid Mech. 43, 583 (2011).
  5. F. H. Busse and R. Simitev, Convection in rotating spherical fluid shells and its dynamo states, in Fluid Dynamics and Dynamos in Astrophysics and Geophysics, edited by A. M. Soward, C. A. Jones, D. W. Hughes, and N. O. Weiss (CRC Press, New York, NY, 2005), pp. 359–392.
  6. P. H. Roberts and G. A. Glatzmaier, Geodynamo theory and simulations, Rev. Mod. Phys. 72, 1081 (2000).
  7. U. R. Christensen, P. Olson, and G. A. Glatzmaier, Numerical modeling of the geodynamo: A systematic parameter study, Geophys. J. Int. 138, 393 (1999).
  8. E. Dormy, L. Oruba, and L. Petitdemange, Three branches of dynamo action, Fluid Dyn. Res. 50, 011415 (2018).
  9. N. Schaeffer, D. Jault, H.-C. Nataf, and A. Fournier, Turbulent geodynamo simulations: A leap towards Earth's core, Geophys. J. Int. 211, 1 (2017).
  10. S. I. Braginsky and P. H. Roberts, Equations governing convection in the Earth's core and the geodynamo, Geophys. Astrophys. Fluid Dynam. 79, 1 (1995).
  11. J. R. Lister and B. A. Buffett, The strength and efficiency of thermal and compositional convection in the geodynamo, Phys. Earth Planet. Inter. 91, 17 (1995).
  12. J. Aubert, J. Aurnou, and J. Wicht, The magnetic structure of convection-driven numerical dynamos, Geophys. J. Int. 172, 945 (2008).
  13. U. R. Christensen and J. Aubert, Scaling properties of convection drivne dynamos in rotating spherical shells and application to planetary magnetic fields, Geophys. J. Int. 166, 97 (2006).
  14. M. Breuer, A. Manglik, J. Wicht, T. Trümper, H. Harder, and U. Hansen, Thermochemically driven convection in a rotating spherical shell, Geophys. J. Int. 183, 150 (2010).
  15. M. Landeau, A. Fournier, H.-C. Nataf, D. Cébron, and N. Schaeffer, Sustaining Earth's magnetic dynamo, Nat. Rev. Earth Environ. 3, 255 (2022).
  16. L. Cappanera, J.-L. Guermond, J. Leorat, and C. Nore, Two spinning ways for precession dynamo, Phys. Rev. E 93, 043113 (2016).
  17. D. Cebron and R. Hollerbach, Tidally driven dynamos in a rotating sphere, Astrophys. J. 789, L25 (2014).
  18. A. Tilgner, On models of precession driven core flow, Studia Geophys. Geod. 42, 232 (1998).
  19. A. Tilgner, Precession driven dynamos, Phys. Fluids 17, 034104 (2005).
  20. A. Tilgner, Kinematic dynamos with precession driven flow in a sphere, Geophys. Astrophys. Fluid Dyn. 101, 1 (2007).
  21. F. Pizzi, A. Giesecke, J. Šimkanin, and F. Stefani, Prograde and retrograde precession of a fluid-filled cylinder, New J. Phys. 23, 123016 (2021).
  22. V. Kumar, F. Pizzi, A. Giesecke, J. Šimkanin, T. Gundrum, M. Ratajczak, and F. Stefani, The effect of nutation angle on the flow inside a precessing cylinder and its dynamo action, Phys. Fluids 35, 014114 (2023).
  23. G. A. Glatzmaier and P. H. Roberts, Rotation and magnetism of Earth's inner core, Science 274, 1887 (1996).
  24. B. A. Buffett and G. A. Glatzmaier, Gravitational braking of inner-core rotation in geodynamo simulations, Geophys. Res. Lett. 27, 3125 (2000).
  25. A. Witze, Has Earth's inner core stopped its strange spin? Nature (London) 614, 19 (2023).
  26. Y. Yang and X. D. Song, Multidecadal variation of the Earth's inner-core rotation, Nat. Geosci. 16, 182 (2023).
  27. C. Kutzner and U. R. Christensen, From stable dipolar towards reversing numerical dynamos, Phys. Earth Planet. Inter. 131, 29 (2002).
  28. U. R. Christensen, J. Aubert, P. Cardin, E. Dormy, S. Gibbons, G. Glatzmaier, E. Grote, Y. Honkura, C. Jones, M. Kono, M. Matsushima, A. Sakuraba, F. Takahashi, A. Tilgner, J. Wicht, and K. Zhang, A numerical dynamo benchmark, Phys. Earth Planet. Inter. 128, 25 (2001).
  29. J. Šimkanin and P. Hejda, Magnetic fields generated by hydromagnetic dynamos at the low Prandtl number in dependence on the Ekman and magnetic Prandtl numbers, Phys. Earth Planet. Inter. 217, 22 (2013).
  30. J. Šimkanin, Polarity reversals in dependence on the Prandtl number and density stratification, Stud. Geophys. Geod. 59, 137 (2015).
  31. J. Šimkanin and J. Kyselica, Transition from laminar to turbulent dynamo: The effect of varying Prandtl number, Geophys. Astrophys. Fluid Dynam. 115, 192 (2021).
  32. J. Aubert, S. Labrosse, and C. Poitou, Modelling the palaeo-evolution of the geodynamo, Geophys. J. Int. 179, 1414 (2009).
  33. J. Šimkanin, J. Kyselica, and P. Guba, Inertial effects on thermochemically driven convection in a spherical shell, Geophys. J. Int. 212, 2194 (2018).
  34. J. Šimkanin, P. Guba, J. Kyselica, and M. Y. Nnaedu, Thermochemical convection in a slowly rotating spherical shell: A transition between prograde and retrograde flows, Geophys. Astrophys. Fluid Dynam. 118, 120 (2024).
  35. E. Dormy, Modélisation numérique de la dynamo terrestre, Ph.D. thesis, Institut de Physique du Globe de Paris, 1997.
  36. E. Dormy, P. Cardin, and D. Jault, MHD flow in a slightly differentially rotating spherical shell, with conducting inner core, in a dipolar magnetic field, Earth Planet. Sci. Lett. 160, 15 (1998).
  37. R. Raynaud and E. Dormy, Intermittency in spherical Couette dynamos, Phys. Rev. E 87, 033011 (2013).
  38. K. K. Zhang and F. H. Busse, On the onset of convection in rotating spherical shells, Geophys. Astrophys. Fluid Dynam. 39, 119 (1987).
  39. E. Dormy, Strong-field spherical dynamos, J. Fluid Mech. 789, 500 (2016).
  40. P. H. Roberts and G. A. Glatzmaier, The geodynamo, past, present and future, Geophys. Astrophys. Fluid Dynam. 94, 47 (2001).
  41. J. Aubert and M. Dumberry, Steady and fluctuating inner core rotation in numerical geodynamo models, Geophys. J. Int. 184, 162 (2011).
  42. G. Pichon, J. Aubert, and A. Fournier, Coupled dynamics of Earth's geomagnetic westward drift and inner core super-rotation, Earth Planet. Sci. Lett. 437, 114 (2016).
  43. J. Šimkanin and J. Kyselica, Magnetic and velocity fields in a dynamo operating at extremely small Ekman and magnetic Prandtl numbers, Contrib. Geophys. Geod. 47, 261 (2017).
  44. J. Brestenský, S. Ševčík, and J. Šimkanin, Magnetoconvection in dependence on Roberts number, Studia Geophys. Geod. 42, 280 (1998).
  45. J. Wicht and D. G. Meduri, A Gaussian model for simulated geomagnetic field reversals, Phys. Earth Planet. Inter. 259, 45 (2016).
  46. P. W. Livermore, R. Hollerbach, and A. Jackson, Electromagnetically driven westward drift and inner-core superrotation in Earth's core, Proc. Natl. Acad. Sci. USA 110, 15914 (2013).
  47. H. Tkalčić, M. Young, T. Bodin, S. Ngo, and M. Sambridge, The shuffling rotation of the Earth's inner core revealed by earthquake doublets, Nat. Geosci. 6, 497 (2013).

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Phys. Rev. Fluids 10, 103705– Published 27 October, 2025
  • Received 27 February 2025
  • Accepted 30 September 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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