Large Scale Flows through the Solar Cycle

Abstract

Large scale flows within the solar convection zone are the primary drivers of the Sun's magnetic activity cycle. Differential rotation amplifies the magnetic field and converts poloidal fields into toroidal fields. Poleward meridional flow near the surface carries magnetic flux that reverses the magnetic poles and converts toroidal fields into poloidal fields. The deeper, equatorward meridional flow carries magnetic flux toward the equator where it must reconnect with oppositely directed fields in the other hemisphere. These axisymmetric flows are themselves driven by large scale convective motions. Given these intimate connections between the large scale flows and solar activity, it would be surprising if there weren't solar cycle variations in the flow characteristics. Some variations, namely the torsional oscillations, are well established. Other variations, namely changes in the meridional flow and in the convective motions themselves, are more controversial. In this presentation I will describe the observed characteristics of the large scale flows and discuss possible variations associated with the solar cycle.