Articles | Volume 15, issue 6
Nonlin. Processes Geophys., 15, 873–880, 2008
https://doi.org/10.5194/npg-15-873-2008
Nonlin. Processes Geophys., 15, 873–880, 2008
https://doi.org/10.5194/npg-15-873-2008

  24 Nov 2008

24 Nov 2008

Direct and inverse cascades in the geodynamo

M. Reshetnyak1 and P. Hejda2 M. Reshetnyak and P. Hejda
  • 1Institute of the Physics of the Earth, Russian Acad. Sci, 123995 Moscow, Russia
  • 2Institute of Geophysics, Academy of Sciences, 141 31 Prague, Czech Republic

Abstract. The rapid rotation of planets causes cyclonic thermal turbulence in their cores which may generate the large-scale magnetic fields observed outside the planets. We investigate numerically a model based on the geodynamo equations in simplified geometry, which enables us to reproduce the main features of small-scale geostrophic flows in physical and wave vector spaces. We find fluxes of kinetic and magnetic energy as a function of the wave number and demonstrate the co-existence of forward and inverse cascades. We also explain the mechanism of magnetic field saturation at the end of the kinematic dynamo regime.