Variation of global and local flows in the solar convection zone during activity cycles 24 and 25

TL;DR

This study analyzes how global and local plasma flows in the solar convection zone vary during solar activity cycles 24 and 25 using extensive helioseismic data, revealing correlations with solar activity and flow structure changes.

Contribution

It provides new insights into the depth-dependent behavior of solar flows and their relation to solar activity cycles, based on prolonged helioseismic observations.

Findings

Flow spectral power is anticorrelated with solar activity near the surface.

Deeper layers show a positive correlation between flow power and activity.

A secondary equatorward meridional flow is observed during Cycle 25.

Abstract

Convection, differential rotation, and meridional circulation of solar plasma are studied based on helioseismic data covering the period from May 2010 to August 2024, significantly prolonged compared to that previously considered. Depth variation in the spatial spectrum of convective motions indicates a superposition of differently scaled flows. The giant-cell-scale component of the velocity field demonstrates a tendency to form meridionally elongated (possibly bananashaped) structures. The integrated spectral power of the flows is anticorrelated with the solar-activity level in the near-surface layers and positively correlates with it in deeper layers. An extended 22-year cycle of zonal flows ("torsional oscillations" of the Sun) and variations of the meridional flows are traced. A secondary meridional flow observed at the epoch of the maximum of Solar Cycle 24 to be directed equatorward in the subsurface layers is clearly manifest in Cycle 25.