GEOSTROPHIC BALANCE AND REVERSALS OF THE GEOMAGNETIC FIELD
Abstract and keywords
Abstract (English):
The 3D geodynamo model in the rapidly rotating spherical shell with heating from below is considered. We show that correlation of the geomagnetic dipole with total magnetic energy in the core depends on the forces balance in the dynamo system. As a result, reversals of the field not always reflect essential changes of the magnetic energy in the core. This result is closely related to the slow decay of the magnetic spectrum at the surface of the core, and in the bulk of the liquid core, especially.

Keywords:
Earth's liquid core, turbulence, geodynamo
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References

1. Buchlin, Dynamo model with thermal convection and with the free-rotating inner core, Planet. Space Sci., v. 50, 2011.

2. Canuto, Spectral methods in Fluids Dynamics, 1998.

3. Christensen, Numerical modeling of the geodynamo: A systematic parameter study, Geophys. J. Int., v. 138, 1999., doi: 10.1046/j.1365-246X.1999.00886.x

4. Christensen, Scaling properties of convection-driven dynamos in rotating spherical shells and application to planetary magnetic fields, Geophys. J. Int., v. 166, 2006., doi: 10.1111/j.1365-246X.2006.03009.x

5. Christensen, Conditions for Earth-like geodynamo models, Earth Planet. Sci. Lett., v. 296, 2010., doi: 10.1016/j.epsl.2010.06.009

6. Frisch, Turbulence: The Legacy of A. N. Kolmogorov, 1995.

7. Glatzmaier, A three-dimension self-consistent computer simulation of a geomagnetic field reversal, Nature, v. 377, 1995., doi: 10.1038/377203a0

8. Gubbins, The Rayleigh number for convection in the Earth's core, Phys. Earth Planet. Int., v. 128, 2001., doi: 10.1016/S0031-9201(01)00273-4

9. Hollerbach, Influence of the Earth's inner core on reversals, Nature, v. 365, 1993., doi: 10.1038/365541a0

10. Hejda, Effects of anisotropy in the geostrophic turbulence, Phys. Earth Planet. Int., v. 177, 2009., doi: 10.1016/j.pepi.2009.08.006

11. Jacobs, Reversals of the Earth's Magnetic Field, 1994., doi: 10.1017/CBO9780511524929

12. Jones, Convection-driven geodynamo models, Phil. Trans.~R.~Soc.~London, v. A358, 2000., doi: 10.1098/rsta.2000.0565

13. Kuang, An Earth-like numerical dynamo model, Nature, v. 389, 1997., doi: 10.1038/38712

14. Kutzner, From stable dipolar towards reversing numerical dynamos, Phys. Earth Planet. Int., v. 131, 2002., doi: 10.1016/S0031-9201(02)00016-X

15. Langel, The main field, In Geomagnetism. Ed. J. A. Jacobs, v. 1, 1987.

16. Reshetnyak, Geomagnetic field intensity and suppression of helicity in the geodynamo, Izvestiya, Physics of the Solid Earth, v. 39, no. 9, 2003.

17. Reshetnyak, Direct and inverse cascades in the geodynamo, Nonlin. Proc. Geophys, v. 15, 2003., doi: 10.5194/npg-15-873-2008

18. Roberts, A test of the frozen-flux approximation using a new geodynamo model, Phil. Trans. R. Soc. Lond., v. A358, 2000., doi: 10.1098/rsta.2000.0576

19. Schrinner, Saturation and time dependence of geodynamo models, Geophys. J. Int., v. 182, 2010., doi: 10.1111/j.1365-246X.2010.04650.x

20. Schubert, Core dynamics, In Treatise on Geophysics. Ed. P. Olson, v. 8, 2007.

21. Simitev, Convection and magnetic field generation in rotating spherical fluid shells, 2004.

22. Wicht, Inner-core conductivity in numerical dynamo simulations, Phys. Earth Planet. Int., v. 132, 2002., doi: 10.1016/S0031-9201(02)00078-X

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