Dynamically consistent nonlinear dynamos driven by convection in a rotating spherical shell. II - Dynamos with cycles and strong feedbacks

Abstract

Nonlinear dynamos with cycles and strong feedback are investigated theoretically. The convectively driven dynamo model of Gilman and Miller (1981) is applied to cases with viscosity and thermal diffusivity reduced by a factor of 10, so that weaker global convection drives an equatorial acceleration of solar magnitude and profile, and differential rotation (DR) makes up nearly 80 percent of the system kinetic energy. The schematics of the dynamo process are introduced, and the design of the calculations is outlined. The results are discussed in terms of the onset of dynamo action, the phenomenology of cyclic solutions, symmetry preservation and switching, total energy statistics, the maintenance of convection and DR against dissipation and feedbacks, changes in DR profiles, maintenance of toroidal and poloidal fields, kinetic and magnetic energy spectra, and applications to the sun and stars. It is found that the model gives cyclic dynamos with periods one order of magnitude shorter than that of the sun. Drawings and graphs illustrating the findings are provided.