Average annual total sunspot area in the last 410 years: The most probable values and limits of their uncertainties

TL;DR

This study reconstructs a 410-year series of average annual sunspot areas using historical and modern data, accounting for uncertainties, and analyzes solar activity cycles and their variations over centuries.

Contribution

It introduces a new long-term sunspot activity index with uncertainty limits, combining multiple data sources and methods for a comprehensive 410-year reconstruction.

Findings

The series fulfills known solar activity rules like Gnevyshev-Ohl and Waldmeier.

Identifies main solar cycle periods of 8.4-13.8 years.

Detects multi-decadal Gleissberg cycles of 50-60 and 90-110 years.

Abstract

The aim of this work is to create a long (410 years) series of average annual total sunspot areas AR - physically-based index of sunspot activity. We used telescopic observations of the AR index in 1832-1868 and 1875-2020, as well as the relationship between AR and long series of sunspot indices SN (ISN version 2.0) and sunspot groups GN (Svalgaard and Schatten (2016) GSN version). The Royal Greenwich observatory series after 1976 is extended by the Kislovodsk Mountain Astronomical Station data. When reconstructing AR from SN, it is taken into account that the function AR = f (SN) has a nonlinear systematic character and uncertainty associated with the heterogeneity of these indices. Therefore, in addition to modeling the most probable AR values, predictive limits of reconstruction uncertainty are determined. In the interval 1610-1699 the reconstruction we carried out on the basis of the GN series using the previously proposed decomposition in pseudo-phase space method (DPS). The resulting series NO21y is freely available online. We show that for this series the empirical Gnevyshev-Ohl rule and Waldmeier effect are fulfilled. Wavelet analysis reveals periodicities of 8.4-13.8 years for the main cycle (with a sharp decrease of the period before the global Maunder and Dalton minima) and a two-component Gleissberg cycle with typical periods of 50-60 years and 90-110 years.