A Three-Dimensional Babcock-Leighton Solar Dynamo Model: Initial Results with Axisymmetric Flows

TL;DR

This paper introduces the STABLE 3D solar dynamo model, which simulates magnetic field generation via bipolar magnetic regions and axisymmetric flows, demonstrating solar-like cyclic behavior under certain conditions.

Contribution

The paper presents the detailed development and verification of the STABLE 3D Babcock-Leighton solar dynamo model, including initial simulation results and analysis of flux generation mechanisms.

Findings

Sustained dynamo solutions depend on BMR size, depth, and number.

Surface differential rotation shears magnetic flux, contributing to toroidal flux.

High turbulent diffusion can hinder dynamo sustainability.

Abstract

The main objective of this paper is to introduce the STABLE (Surface flux Transport And Babcock-LEighton) solar dynamo model. STABLE is a 3D Babcock-Leighton/Flux Transport dynamo model in which the source of poloidal field is the explicit emergence, distortion, and dispersal of bipolar magnetic regions (BMRs). Here we describe the STABLE model in more detail than we have previously and we verify it by reproducing a 2D mean-field benchmark. We also present some representative dynamo simulations, focusing on the special case of kinematic magnetic induction and axisymmetric flow fields. Not all solutions are supercritical; it can be a challenge for the BL mechanism to sustain the dynamo when the turbulent diffusion near the surface is $\geq 10^{12}$ cm$^2$ s$^{-1}$. However, if BMRs are sufficiently large, deep, and numerous, then sustained, cyclic, dynamo solutions can be found that exhibit solar-like features. Furthermore, we find that the shearing of radial magnetic flux by the surface differential rotation can account for most of the net toroidal flux generation in each hemisphere, as has been recently argued for the Sun by Cameron & Schussler (2015).