Solar parity issue with flux-transport dynamo

TL;DR

This study uses axisymmetric kinematic dynamo simulations to explore how turbulent diffusivity and meridional flow influence the Sun's magnetic parity, revealing key factors that determine whether the magnetic field is dipolar or quadrupolar.

Contribution

It provides a detailed analysis of the conditions under which the solar magnetic field adopts dipolar or quadrupolar configurations, focusing on diffusivity and meridional flow effects.

Findings

Stronger surface diffusivity favors dipole magnetic fields.

Thinner strong diffusivity layers near the surface promote dipolar fields.

Faster meridional flow tends to produce quadrupolar magnetic configurations.

Abstract

We investigated the dependence of the solar magnetic parity between the hemispheres on two important parameters, the turbulent diffusivity and the meridional flow, by means of axisymmetric kinematic dynamo simulations based on the flux-transport dynamo model. It is known that the coupling of the magnetic field between hemispheres due to turbulent diffusivity is an important factor for the solar parity issue, but the detailed criterion for the generation of the dipole field has not been investigated. Our conclusions are as follows. (1) The stronger diffusivity near the surface is more likely to cause the magnetic field to be a dipole. (2) The thinner layer of the strong diffusivity near the surface is also more apt to generate a dipolar magnetic field. (3) The faster meridional flow is more prone to cause the magnetic field to be a quadrupole, i.e., symmetric about the equator. These results show that turbulent diffusivity and meridional flow are crucial for the configuration of the solar global magnetic field.