How Large-scale Flows May Influence Solar Activity

摘要

Large-scale flows within the solar convection zone are the pri-mary drivers of the Sun's magnetic activity cycle and play important roles inshaping the Suns magnetic field. Differential rotation amplifies the magneticfield through its shearing action and converts poloidal field into toroidal field.Poleward meridional flow near the surface carries magnetic flux that, reversesthe magnetic poles at about the time of solar maximum. The deeper, equator-ward meridional flow can carry magnetic flux back toward the lower latitudeswhere it erupts through the surface to form tilted active regions that converttoroidal fields into oppositely directed poloidal fields. These axisymmetric flowsare themselves driven by large-scale convective motions. The effects of the Sunsrotation on convection produce velocity correlations that can maintain both thedifferential rotation and the meridional circulation. These convective motionscan also influence solar activity directly by shaping the magnetic field pattern.While considerable theoretical advances have been made toward understandingthese large-scale flows, outstanding problems in matching theory to observationsstill remain.