Solar activity in the past and the chaotic behaviour of the dynamo

TL;DR

This paper reviews historical solar activity records, emphasizing sunspot positions and isotope proxies, to explore the complex, chaotic behavior of the solar dynamo over millennia.

Contribution

It highlights the importance of sunspot positional data and isotope proxies in understanding the solar dynamo's variable solutions and chaotic nature.

Findings

Recurrent grand minima identified over 9500 years.

Solar dynamo exhibits multiple solutions with different symmetries.

Episodes of strong and mild modulation suggest chaotic dynamo behavior.

Abstract

The record of solar activity is reviewed here with emphasis on peculiarities. Since sunspot positions tell us a lot more about the solar dynamo than the various global sunspot numbers, we first focus on the records of telescopic observations of sunspots leading to positional information. Then we turn to the proxy record from cosmogenic isotope abundances, which shows recurrent grand minima over the last 9500 years. The apparent distinction between episodes of strong modulation, and intervening episodes with milder modulation and weaker overall activity, hints at the solar dynamo following a variety of solutions, with different symmetries, over the course of millennia.