Standard & Combined Method predictions

12-month ahead predictions of the monthly smoothed sunspot number: SC (red) : prediction method based on an interpolation of Waldmeier's standard curves; It is only based on the sunspot number series. CM (green) : method (from K. Denkmayr and P. Cugnon) combining a regression technique applied to the sunspot number series with the aa geomagnetic index used as a precursor (improved predictions during the minimum phase between solar cycles).