Dynamics of Subsurface Flows in Solar Active Regions During the May 2024 Storm

TL;DR

This study analyzes the subsurface plasma flows in solar active regions during the May 2024 solar storm, revealing how flow dynamics relate to flare activity and magnetic properties using ring-diagram analysis.

Contribution

It provides new insights into the depth-dependent evolution of subsurface flows and their correlation with flare activity during a major solar storm.

Findings

Flares tend to occur when the normalized helicity gradient variance peaks.

Pronounced temporal and depth-dependent variations in flow divergence, vorticity, and kinetic helicity.

Subsurface flow dynamics are closely related to surface magnetic properties.

Abstract

In May 2024, the Sun exhibited intense magnetic activity, marked by numerous high-intensity flares resulting from the interaction and merging of NOAA ARs 13664 and 13668 in the southern hemisphere and AR 13663 in the northern hemisphere. Notably, AR 13664 displayed an extended lifetime, remaining visible after a full solar rotation and continuing to produce significant flaring activity. In this study, we investigate the evolution of sub-photospheric plasma flows associated with these ARs during their disk passage using ring-diagram analysis of SDO/HMI Dopplergrams. We analyze flow divergence, vorticity, and kinetic helicity across depths from the surface to 25 Mm, revealing pronounced temporal and depth-dependent variations. Our observations indicate that the majority of flares occur on the days when the Normalized Helicity Gradient Variance, a measure of kinetic helicity spread, peaks or on the following day. Furthermore, we examine the relationship between subsurface flow dynamics and surface magnetic properties of these complex active regions to understand the interaction between them.