Direct and inverse cascades in the geodynamo
- 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.