The magnetic helicity density patterns from non-axisymmetric solar dynamo

TL;DR

This study investigates magnetic helicity density patterns resulting from bipolar regions in the solar dynamo, revealing their dependence on ambient magnetic fields, tilt angles, and fluxes, with implications for understanding solar magnetic activity.

Contribution

It demonstrates how bipolar regions influence helicity density patterns and their relation to the large-scale magnetic field, using a dynamo model and conservation laws.

Findings

Helicity density patterns depend on ambient magnetic field configuration.

Patterns show quadrupole distribution around bipolar regions.

Helicity fluxes have negligible effect on dynamo saturation.

Abstract

In the paper we study the helicity density patterns which can result from the emerging bipolar regions. Using the relevant dynamo model and the magnetic helicity conservation law we find that the helicity density pattern around the bipolar regions depends on the configuration of the ambient large-scale magnetic field, and in general they show the quadrupole distribution. The position of this pattern relative to the equator can depend on the tilt of the bipolar region. We compute the time-latitude diagrams of the helicity density evolution. The longitudinally averaged effect of the bipolar regions show two bands of sign for the density distribution in each hemisphere. Similar helicity density patterns are provided by the helicity density flux from the emerging bipolar regions subjected to the surface differential rotation. Examining effect of helicity fluxes from the bipolar regions on the large-scale dynamo we find that its effect to the dynamo saturation is negligible.