Grand Minima and North-South Asymmetry of Solar Activity

TL;DR

This paper presents a solar dynamo model that reproduces grand minima and north-south asymmetry in solar activity, highlighting their statistical independence and potential as indicators of solar activity transitions.

Contribution

A new spherical shell dynamo model incorporating random poloidal field generation and latitude dependence, explaining grand minima and asymmetry in solar activity.

Findings

Model reproduces Maunder minimum-like epochs.

North-south asymmetry correlates with grand minima.

Grand minima occur independently, following a Poisson process.

Abstract

A solar-type dynamo model in a spherical shell is developed with allowance for random dependence of the poloidal field generation mechanism on time and latitude. The model shows repeatable epochs of strongly decreased amplitude of magnetic cycles similar to the Maunder minimum of solar activity. Random dependence of dynamo-parameters on latitude brakes the equatorial symmetry of generated fields. The model shows the correlation of the occurrence of grand minima with deviations in the dynamo-field from dipolar parity. An increased north-south asymmetry of magnetic activity can, therefore, be an indicator of transitions to grand minima. Qualitative interpretation of this correlation is suggested. Statistics of grand minima in the model are close to the Poisson random process indicating that the onset of a grand minimum is statistically independent of preceding minima.