Effects of Solar Active Regions on Meridional Flows

TL;DR

This study investigates how solar active regions influence meridional flows, revealing that inflows into active regions significantly affect near-equatorial flow variations, with implications for understanding solar cycle dynamics.

Contribution

It extends previous research by analyzing the latitudinal and longitudinal structure of meridional flows in magnetic regions using helioseismology data from 1996-2002.

Findings

Mass flows around active regions are dominated by inflows.

Local flows are more significant around leading magnetic polarities.

The effect explains part of the solar cycle variation at low latitudes.

Abstract

The aim of this paper is to extend our previous study of the solar-cycle variations of the meridional flows and to investigate their latitudinal and longitudinal structure in the subphotospheric layer, especially their variations in magnetic regions. Helioseismology observations indicate that mass flows around active regions are dominated by inflows into those regions. On average, those local flows are more important around leading magnetic polarities of active regions than around the following polarities, and depend on the evolutionary stage of particular active regions. We present a statistical study based on MDI/SOHO observations of 1996-2002 and show that this effect explains a significant part of the cyclic change of meridional flows in near-equatorial regions, but not at higher latitudes. A different mechanism driving solar-cycle variations of the meridional flow probably operates.