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Table 2 A selection of early forecasts for Cycle 25

From: Solar cycle prediction

Category

Minimum

Maximum

Peak amplitude

References

Internal precursors

2019.9

2023.8

175 (154–202)

Li et al. (2015)

External precursor

 Polar precursor

  

\(117\pm 15\)

Table 1 here

 Polar precursor

  

\(136\pm 48\)

Pesnell and Schatten (2018)

 Helicity

  

117

Hawkes and Berger (2018)

 SoDA

 

\(2025.2\pm 1.5\)

\(120\pm 39\)

Based on Pesnell and Schatten (2018)

 Rush-to-the-poles

2019.4

2024.8

130

Petrovay et al. (2018)

Model-based: SFT

 SFT

  

\(124\pm 31\)

Jiang et al. (2018)

 AFT

2020.9

 

110

Upton and Hathaway (2018)

Model-based: dynamo

 \(2{\times }2\)D

\(2020.5\pm 0.12\)

\(2027.2\pm 1.0\)

\(89^{+29}_{-14}\)

Labonville et al. (2019)

 Truncated

2019–2020

\(2024\pm 1\)

\(90\pm 15\)

Kitiashvili (2016)

Spectral

 Wavelet decomposition tree

 

2023.4

132

Rigozo et al. (2011)

Attractor analysis

 Simplex projection analysis

 

\(2024.0\pm 0.6\)

\(103\pm 25\)

Singh and Bhargawa (2017)

 Simplex proj./time-delay

 

\(2023.2\pm 1.1\)

\(154\pm 12\)

Sarp et al. (2018)

Neural networks

 Neuro-fuzzy

 

2022

\(90.7\pm 8\)

Attia et al. (2013)

 Spatiotemporal

 

2022–2023

\(57\pm 17\)

Covas et al. (2019)

Cycle 24 (comparison)

2008.9

2014.3

116

 
  1. In the case of SFT models, forecasts were obtained by multiplying the amplitude of Cycle 24 with the predicted % increase in polar field strength between the two minima. Errors resulting from a natural scatter in the polar field–cycle ampliude relation are therefore not included in the error range given