Self-excitation of motions in near-convection zones and the generation of solar magnetic field

In view of the recently discovered time variations in rotation velocity wit hin the solar differentially rotating tachocline (Howe et al. 2000), we stu dy conditions for the equilibrium and excitation of motions in nonrigidly r otating magnetized layers of the radiative zones located near the boundarie s of the convection zone. The emphasis is on the possible relationship betw een quasi-periodic tachocline pulsations and the generation of a nonaxisymm etric magnetic field in the convection zone. This field generation is studi ed under the assumption that it results from a reduction in the expenditure of energy on convective heat transport. The (antisymmetric about the equat or) field is shown to increase in strength if there are both a radial gradi ent in angular velocity and steady-state axisymmetric meridional circulatio n of matter. The sense of circulation is assumed to change (causing the sig n of the generated field to change) after the maximum permissible field str ength is reached. This is apparently attributable to the excitation of the corresponding turbulent viscosity of the medium. It is also important that the cyclic field variations under discussion are accompanied by variations in solar-type dipole magnetic field. (C) 2001 MAIK "Nauka/Interperiodica".