Living Reviews in Solar Physics

"The Solar Cycle"
by
David H. Hathaway  

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Abstract
1 Introduction
2 The Solar Cycle Discovered
2.1 Schwabe’s discovery
2.2 Wolf’s relative sunspot number
2.3 Wolf’s reconstruction of earlier data
3 Solar Activity Data
3.1 Sunspot numbers
3.2 Sunspot areas
3.3 10.7 cm solar flux
3.4 Total irradiance
3.5 Magnetic field
3.6 Flares and Coronal Mass Ejections
3.7 Geomagnetic activity
3.8 Cosmic rays
3.9 Radioisotopes in tree rings and ice cores
4 Individual Cycle Characteristics
4.1 Minima and maxima
4.2 Smoothing
4.3 Cycle periods
4.4 Cycle amplitudes
4.5 Cycle shape
4.6 Rise time vs. amplitude (The Waldmeier Effect)
4.7 Period vs. amplitude
4.8 Active latitudes
4.9 Active hemispheres
4.10 Active longitudes
5 Long-Term Variability
5.1 The Maunder Minimum
5.2 The secular trend
5.3 The Gleissberg Cycle
5.4 Gnevyshev–Ohl Rule (Even–Odd Effect)
5.5 Long-term variations from radioisotope studies
5.6 The Suess cycle
6 Short-Term Variability
6.1 154-day periodicity
6.2 Quasi-biennial variations and double peaked maxima
7 Solar Cycle Predictions
7.1 Predicting an ongoing cycle
7.2 Predicting future cycle amplitudes based on cycle statistics
7.3 Predicting future cycle amplitudes based on geomagnetic precursors
7.4 Predicting future cycle amplitudes based on dynamo theory
8 Conclusions
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