Solar small-scale dynamo and polarity of sunspot groups

TL;DR

This paper investigates the role of small-scale dynamo action in the Sun by analyzing the occurrence of anti-Hale sunspot groups, finding their prevalence peaks during solar minima, supporting the dynamo hypothesis.

Contribution

It provides observational evidence linking anti-Hale sunspot groups' distribution to small-scale dynamo activity in the solar convective zone.

Findings

Anti-Hale sunspot groups peak during solar minima.

The percentage of anti-Hale groups is independent of the solar cycle phase.

Results support the existence of small-scale dynamo action in the Sun.

Abstract

In order to clarify a possible role of small-scale dynamo in formation of solar magnetic field, we suggest an observational test for small-scale dynamo action based on statistics of anti-Hale sunspot groups. As we have shown, according to theoretical expectations the small-scale dynamo action has to provide a population of sunspot groups which do not follow the Hale polarity law, and the density of such groups on the time-latitude diagram is expected to be independent on the phase of the solar cycle. Correspondingly, a percentage of the anti-Hale groups is expected to reach its maximum values during solar minima. For several solar cycles, we considered statistics of anti-Hale groups obtained by several scientific teams, including ours, to find that the percentage of anti-Hale groups becomes indeed maximal during a solar minimum. Our interpretation is that this fact may be explained by the small-scale dynamo action inside the solar convective zone.