Overlapping Magnetic Activity Cycles and the Sunspot Number: Forecasting Sunspot Cycle 25 Amplitude

Abstract

The Sun exhibits a well-observed modulation in the number of spots on its disk over a period of about 11 years. From the dawn of modern observational astronomy sunspots have presented a challenge to understanding -- their quasi-periodic variation in number, first noted 175 years ago, stimulates community-wide interest to this day. A large number of techniques are able to explain the temporal landmarks, (geometric) shape, and amplitude of sunspot "cycles," however forecasting these features accurately in advance remains elusive. Recent observationally-motivated studies have illustrated a relationship between the Sun's 22-year (Hale) magnetic cycle and the production of the sunspot cycle landmarks and patterns, but not the amplitude of the sunspot cycle. Using (discrete) Hilbert transforms on more than 270 years of (monthly) sunspot numbers we robustly identify the so-called "termination" events that mark the end of the previous 11-yr sunspot cycle, the enhancement/acceleration of the present cycle, and the end of 22-yr magnetic activity cycles. Using these we extract a relationship between the temporal spacing of terminators and the magnitude of sunspot cycles. Given this relationship and our prediction of a terminator event in 2020, we deduce that Sunspot Cycle 25 could have a magnitude that rivals the top few since records began. This outcome would be in stark contrast to the community consensus estimate of sunspot cycle 25 magnitude.

arXiv comment12 pages, 6 figures. Submitted to Nature Astronomy 3/9/2020. In third iteration with reviewers. Revised and reformatted for Solar Physics - 15 pages, 8 figures. 8/25/2020

References in corpus (10)

• The Solar Cycle
• Revisiting the Sunspot Number
• Solar cycle prediction
• Prediction of the strength and timing of sunspot cycle 25 reveal decadal-scale space environmental conditions
• An Updated Solar Cycle 25 Prediction with AFT: The Modern Minimum
• Deciphering Solar Magnetic Activity I: On The Relationship Between The Sunspot Cycle And The Evolution Of Small Magnetic Features
• The Global Solar Dynamo
• What the sudden death of solar cycles can tell us about the nature of the solar interior
• Timing Terminators: Forecasting Sunspot Cycle 25 Onset
• Application of Synoptic Magnetograms to Global Solar Activity Forecast

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