Changes of the solar meridional velocity profile during cycle 23 explained by flows towards the activity belts

TL;DR

This study explains the observed variations in the solar meridional flow during cycle 23 as resulting from localized inflows towards active regions, rather than changes in the overall flow amplitude, refining our understanding of solar dynamics.

Contribution

The paper demonstrates that cycle-related variations in meridional flow can be explained by flows towards activity belts, without requiring changes in the overall flow amplitude.

Findings

Variations in the $P_2^1$ term are due to localized inflows.

No need to assume overall flow amplitude changes.

Flow patterns are linked to magnetic flux distribution.

Abstract

The solar meridional flow is an important ingredient in Babcock-Leighton type models of the solar dynamo. Global variations of this flow have been suggested to explain the variations in the amplitudes and lengths of the activity cycles. Recently, cycle-related variations in the amplitude of the $P_2^1$ term in the Legendre decomposition of the observed meridional flow have been reported. The result is often interpreted in terms of an overall variation in the flow amplitude during the activity cycle. Using a semi-empirical model based upon the observed distribution of magnetic flux on the solar surface, we show that the reported variations of the $P_2^1$ term can be explained by the observed localized inflows into the active region belts. No variation of the overall meridional flow amplitude is required.