The mean-field dynamo model

TL;DR

This paper investigates the 2D Parker mean-field dynamo equations, demonstrating how smooth $ extalpha$ and $ extomega$ profiles produce realistic dipole magnetic fields, while fluctuations and quenching affect field configurations and energy spectra.

Contribution

It provides new insights into how smooth and fluctuating $ extalpha$-effects influence magnetic field configurations in mean-field dynamo models.

Findings

Smooth profiles produce realistic dipole magnetic fields.

Fluctuating $ extalpha$-effects increase small-scale magnetic energy.

Dynamic $ extalpha$-quenching results in coexisting weak and strong solutions.

Abstract

The 2D Parker's mean-field dynamo equations with a various distributions of the $\alpha$- and $\omega$-effects are considered. We show that smooth profiles of $\alpha$ and $\omega$ can produce dipole configuration of the magnetic field with the realistic magnetic energy spectrum. We emphasize that fluctuating $\alpha$-effect leads to increase of the magnetic energy at the small scales, breaking the dipole configuration of the field. The considered geostrophic profiles of $\alpha$ and $\omega$ correspond to the small-scale polarwards/equatorwards travelling waves with the small dipole field contribution. The same result is observed for the dynamic form of the $\alpha$-quenching, where two branches of the weak and strong solution coexist.