The model is empirically derived by combining and analyzing over 100 years of solar observations from different telescopes. We analyzed this long time series of data to mathematically describe two key properties of the Sun’s magnetic field: the faster the Sun’s activity increases at the start of a cycle, the more intense the cycle is (known as the Waldemeier effect), and that the strength of odd-cycles depends on the strengths of the previous even-cycle. To predict the strength of our current solar cycle 25, these findings are combined with the observations made during the even previous cycle 24. The prediction for plage and sunspot are illustrated in Figure.
As a result, we anticipate that cycle 25 (began in December 2019) will peak in 2024 and last for about 12 years, slightly longer than cycle 24. We also found that, in terms of sunspot and plage area coverage, the amplitude of cycle 25 will be similar or slightly higher than cycle 24. Figure shows that the model is in agreement with the sunspot and plage coverages measured at the San Fernando Observatory at the beginning of cycle 25.
The Astrophysical Journal Letters, Volume 922, Issue 1, id.L12, pp., 2021.