The Sun’s near surface shear layer (NSSL) is characterized by using HMI ring-diagram results. It is found the NSSL is composed of three distinct layers: a deeper larger region with a small shear, a narrow middle layer with a strong shear, and a layer very close to the surface.
An analysis of zonal flow acceleration/deceleration inside the Sun reveals patterns of dynamo waves, and suggests that the primary seat of the dynamo is located in a high-latitude zone of the tachocline.
New helioseismic analysis of the Sun’s subsurface zonal flows shows the equator-migrating branch of the faster-than-average rotation, a sign of the Solar Cycle 25.
Subsurface meridional flow speed shows an anti-correlation with the magnetic flux being transported poleward above the latitude of 35°. In the lower latitude, the residual meridional flow, after a long-time mean profile is subtracted, shows converging flow toward the activity belts.