Evolution of the inner core of the Earth: consequences for geodynamo

M. Reshetnyak^{1, 2}

¹ Institute of the Physics of the Earth, 10 B.Gruzinskaya str., Moscow 123995, Russia
² Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation RAS, 4 Kaluzhskoe rd., Moscow, Troitsk 108840, Russia

Abstract
Using models of the Earth's core evolution and the length of the day observations, the change of the dimensionless geodynamo parameters is considered. The evolutionary model includes cooling of the liquid adiabatic core, growing solid core, and the region in the outer part of the core with a subadiabatic temperature gradient. The model covers the time period 4.5 Ga in the past till 1.5 Gy to the future and produces an evolution of the energy sources of thermal and compositional convection, spatial scales of the convective zone. These quantities are used for Ekman, Rayleigh and Rossby numbers' estimates. So far as these numbers determine the regime of the geomagnetic field generation, we discuss the evolution of the geomagnetic field over the Earth's evolution. Tables 1, Figs 3, Refs 14.