**Bulletin of Taras Shevchenko National University of Kyiv. Astronomy, no. 65, p. 35-39 (2022)**

**Forecast of the maximum 25th cуcle of Solar activity based on data on the rate of increase in the number of sunspots**

**V. Efimenko, PhD,**

**V. Lozitsky, Dr Hab.**

**Taras Shevchenko National University of Kyiv, Kyiv, Ukraine**

**Abstract**

Based on data on 24 previous solar cycles, 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 was considered. It turned out that the result of forecast of cycle amplitude depends on which section of the growth curve is taken as a basis for forecasting, as well as whether all 24 cycles are taken into account, or only the odd ones. The prediction result is also affected by the initial assumption about monotonicity or non-monotonicity of the growth phase. It was concluded that, most likely, the maximum smoothed number of sunspots in the 25th cycle 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 Gnievyshev-Ohl rule. With such parameters of this cycle, there are no signs of approaching the deep minimum of the age cycle in the middle of the 21st century.

**Key words
**Sun, solar activity, number of sunspots, amplitude forecast of the 25th cycle, Hnievyshev-Ohl rule, minimum of the age cycle.

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