Sunspot periodicity

TL;DR

This paper discusses the ~11-year sunspot cycle, its complex origins, and the importance of understanding its true periodicity beyond simple statistical correlation, considering alternative solar activity indicators.

Contribution

It critically examines the traditional view of the sunspot cycle, explores planetary influences, and emphasizes the need for a deeper understanding of solar periodicity beyond the standard model.

Findings

The ~11 yr cycle is complex and not fully explained by existing dynamo models.

Planetary dynamics may play a role in solar cycle periodicity.

Alternative indicators like solar wind flux could be more fundamental than sunspots.

Abstract

The Schwabe (~11 yr) value for the annual sunspot number is sometimes uncritically applied to other measures of solar activity, direct and indirect, including the 10.7 cm radio flux, the inflow of galactic cosmic rays, solar flare frequency, terrestrial weather, and components of space climate, with the risk of a resulting loss of information. The ruling (Babcock) hypothesis and its derivatives link the sunspot cycle to dynamo processes mediated by differential solar rotation, but despite 60 years of observation and analysis the ~11 yr periodicity remains difficult to model; the possible contribution of planetary dynamics is undergoing a revival. The various solar sequences that genuinely display an ~11 yr cycle stand to benefit from an understanding of its periodicity that goes beyond statistical kinship. The outcome could ironically prompt the demotion of sunspots from their dominant historical role in favour of other possible indicators of solar cyclicity, such as the solar wind flux and its isotopic signatures, even if they are less accessible.