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 | |