Hemispheric magnetic asymmetry and cross-equatorial circulation cells within the sun’s near-surface shear layer

Abstract

Using time─distance helioseismic measurements of meridional flow in the near-surface shear layer over a period of 14 yr starting from 2010 May, we probe the depth structure and evolution of its cross-equatorial part. We confirm that the hemispheric magnetic asymmetry determines the amplitude and direction of such flows. Additionally, we find that these flows turn over and change direction at depths below 0.97R⊙ forming circulation cells with lifetimes dictated again by the hemispheric magnetic imbalance, which is dominated by the occurrences of large sunspots. We also examine connections between cross-equatorial magnetic flux plumes and flows and discuss their implications for the equatorial flux cancellation/submergence and the poleward transport of flux.