Solar Dynamo Model with Diamagnetic Pumping and Nonlocal Alpha-Effect

TL;DR

This paper presents a solar dynamo model combining diamagnetic pumping and a nonlocal alpha-effect, successfully reproducing key solar magnetic activity features without reducing magnetic diffusivity, and highlights the importance of meridional flow for realistic butterfly diagrams.

Contribution

It introduces a novel combination of diamagnetic pumping and nonlocal alpha-effect in a solar dynamo model, improving the reproduction of solar cycle features.

Findings

Reproduces solar cycle period without lowering magnetic diffusivity.

Global magnetic fields are antisymmetric and have a high toroidal-to-poloidal ratio.

Meridional flow is essential for matching observed butterfly diagrams.

Abstract

A combination of diamagnetic pumping and a nonlocal alpha-effect of the Babcock-Leighton type in a solar dynamo model helps to reproduce observations of solar magnetic activity. The period of the solar cycle can be reproduced without reducing magnetic diffusivity in the bulk of the convection zone below the standard mixing-length value of $10^{13}$ cm$^2$s$^{-1}$. The simulated global fields are antisymmetric about the equator and the toroidal-to-poloidal field ratio is about a thousand. The time-latitude diagrams of magnetic fields in the model without meridional flow, however, differ from observations. Only when the meridional flow is included and the alpha-effect profile peaking at mid latitudes is applied, can the observational butterfly diagrams be reproduced.