Solar cycle 25 amplitude prediction based on sunspot number increase rate

Abstract

We propose a prediction of the amplitude of the 25th cycle of solar activity based on the analysis of data on 24 previous solar cycles, which relate to the statistical relationship between the rate of increase in the number of sunspots in the phase of the growth curve and the amplitude of the cycle. It turned out that the forecasting result depends on several initial assumptions, in particular, which section of the growth curve is taken into account for forecasting, as well as whether all 24 cycles are considered, or only the odd ones. The assumption of a monotonic or non-monotonic growth curve also plays an important role. Regarding the latter, the cluster analysis showed that until the 35th month of the cycle, there are no visible signs of non-monotonicity of the growth curve, similar to the one that was in the 24th cycle. We conclude that the maximum smoothed number of sunspots in the 25th cycle Wmax (25), most likely, should be equal to 185 ± 18 units in the new system, which corresponds to the average power of the solar cycle, with the implementation of the Hnievyshev-Ohl rule. With such parameters of this cycle, there are no signs of approaching the deep minimum of the age cycle in the middle 21st century. This does not exclude the fact that this deep age minimum can occur suddenly and sharply immediately after the 25th cycle, as was the case, for example, in the Dalton minimum. A possible sign of the upcoming age cycle may be the abnormally long decline phase of the current 25th cycle, about 10 years, as it was in the 4th cycle.