Quenching of Meridional Circulation in Flux Transport Dynamo Models

TL;DR

This paper investigates how including a magnetic field-dependent quenching of the Sun's meridional circulation affects flux transport dynamo models, revealing stability conditions and reproducing observed solar cycle variations.

Contribution

It introduces a parametric quenching mechanism for meridional circulation linked to magnetic field strength in solar dynamo models, analyzing its impact on stability and solar cycle behavior.

Findings

Quenching causes instability in low diffusivity models.

High diffusivity models remain stable despite quenching.

A solar-like solution shows periodic meridional circulation variation.

Abstract

Guided by the recent observational result that the meridional circulation of the Sun becomes weaker at the time of the sunspot maximum, we have included a parametric quenching of the meridional circulation in solar dynamo models such that the meridional circulation becomes weaker when the magnetic field at the base of the convection zone is stronger. We find that a flux transport solar dynamo tends to become unstable on including this quenching of meridional circulation if the diffusivity in the convection zone is less than about 2 * 10^{11} cm^2/s. The quenching of alpha, however, has a stabilizing effect and it is possible to stabilize a dynamo with low diffusivity with sufficiently strong alpha-quenching. For dynamo models with high diffusivity, the quenching of meridional circulation does not produce a large effect and the dynamo remains stable. We present a solar-like solution from a dynamo model with diffusivity 2.8 * 10^{12} cm^2/s in which the quenching of meridional circulation makes the meridional circulation vary periodically with solar cycle as observed and does not have any other significant effect on the dynamo.