The Solar Cycle

TL;DR

This paper reviews the 11-year solar cycle, detailing its characteristics, variability, and indicators, and discusses methods for predicting future cycles based on historical data and recent cycles 23 and 24.

Contribution

It provides a comprehensive overview of solar cycle features, variability patterns, and advances in prediction techniques, integrating multiple solar activity indicators.

Findings

Solar activity correlates with sunspots, radio flux, and irradiance.

Cycle variability includes Maunder Minimum and Gleissberg Cycle.

Prediction methods are evolving with recent cycle analyses.

Abstract

The Solar Cycle is reviewed. The 11-year cycle of solar activity is characterized by the rise and fall in the numbers and surface area of sunspots. A number of other solar activity indicators also vary in association with the sunspots including; the 10.7cm radio flux, the total solar irradiance, the magnetic field, flares and coronal mass ejections, geomagnetic activity, galactic cosmic ray fluxes, and radioisotopes in tree rings and ice cores. Individual solar cycles are characterized by their maxima and minima, cycle periods and amplitudes, cycle shape, the equatorward drift of the active latitudes, hemispheric asymmetries, and active longitudes. Cycle-to-cycle variability includes the Maunder Minimum, the Gleissberg Cycle, and the Gnevyshev-Ohl (even-odd) Rule. Short-term variability includes the 154-day periodicity, quasi-biennial variations, and double-peaked maxima. We conclude with an examination of prediction techniques for the solar cycle and a closer look at cycles 23 and 24.