Prévision du cycle des taches solaires

Given the dates tand Tfor sunspot cycle minima and maxima and allowing for a probable secondary modulation with an approximate 16 cycles period, the author applies a forecasting method developed earlier to sunspot cycles n ^os 21 and 22. According to the resulting prediction these coming elementary cycles will be longer (about 14 years) than the 11 years average. Predicted values for the Zürich number Rare about 80 and 50, respectively.