An alternative measure of solar activity from detailed sunspot datasets

TL;DR

This paper proposes an alternative solar activity measure based on sunspot area data, addressing ambiguities in traditional sunspot numbers by focusing on magnetic flux as a more objective indicator.

Contribution

It introduces a new activity index derived from detailed sunspot area data, offering a more physically meaningful measure of solar activity.

Findings

Traditional sunspot numbers have subjective and objective ambiguities.

The proposed index is based on magnetic flux derived from sunspot areas.

Debrecen sunspot databases enable calibration of the new activity measure.

Abstract

The sunspot number is analyzed by using detailed sunspot data, including aspects of observability, sunspot sizes, and proper identification of sunspot groups as discrete entities of the solar activity. The tests show that besides the subjective factors there are also objective causes of the ambiguities in the series of sunspot numbers. To introduce an alternative activity measure the physical meaning of the sunspot number has to be reconsidered. It contains two components whose numbers are governed by different physical mechanisms, this is one source of the ambiguity. This article suggests an activity index, which is the amount of emerged magnetic flux. The only long-term proxy measure is the detailed sunspot area dataset with proper calibration to the magnetic flux amount. The Debrecen sunspot databases provide an appropriate source for the establishment of the suggested activity index.