Kinematic Dynamo Model of a Solar Magnetic Cycle

Abstract

The paper deals with the problem of explaining the origin and nature of the space-time variations in the magnetic activity of the Sun. It presents a new hydrodynamic model of the solar magnetic cycle, which uses helioseismological data on the differential rotation of the solar convective zone. The model is based on the hypothesis of the emergence of global flows as a result of the loss of stability of a differentially rotating plasma layer in the convective zone. First, the hydrodynamic global plasma flows are calculated without accounting for the effect of a magnetic field on them. Under this condition, it is shown that the solutions found describe all global flows observed on the surface of the Sun: permanent meridional circulation from the equator to the poles, torsional oscillations and space-time variations of the meridional flow. We conclude that the last two flows are azimuthal and meridional components of a single three-dimensional global hydrodynamic flow. Second, to simulate the dynamics of the magnetic field, the found velocities of global migrating flows and the spatial profile of the angular velocity of the internal differential rotation of the solar convective zone obtained from helioseismic measurements were used. Good coincidences have been obtained between the characteristics of the calculated dynamics of global migrating flows and the variable global magnetic fields generated by them with the observed values on the solar surface. An explanation is given for some phenomena on the surface of the Sun, which could not be explained within the framework of the available models.