Relationship Between Subsurface Flows and Magnetic Field Evolution in Solar Cycle 24

Abstract:

Local time-distance helioseismology and magnetic field measurements from the HMI instrument on SDO provide unique high-resolution data that allow us to investigate detailed dynamics of the upper convection zone and its relation to the magnetic field evolution during the first five years of the current solar cycle. This study is focused on the understanding the role of the near-surface shear layer (NSSL) in the dynamo process, generation, emergence and transport of the solar magnetic flux. The helioseismology data represent 3D flow maps in the depth range of 0-20 Mm, obtained uninterruptedly every 8 hours for almost the whole solar disk with the spatial sampling of two arcsec. We calculate the flow characteristics (such as divergence, vorticity and kinetic helicity) on different spatio-temporal scales from supergranulation to global-scale zonal and meridional flows. We investigate the multi-scale organization of the subsurface flows, including the inflows into active regions, the hemispheric `flip-flop’ asymmetry of variations of the meridional flows, the structure and dynamics of torsional oscillations, and compare the flow behavior with the evolution of the observed magnetic activity.