Shantanu Jain, Astrid Veronig, Werner Pötzi, Frédéric Clette, Olga Sutyrina, Mateja Dumbovic

Forecasting the solar cycle amplitude is important for many space weather applications. We demonstrate a steady relationship between the maximal growth rate of sunspot activity in the cycle ascending phase and the subsequent cycle amplitude using four data sets of solar activity indices: total sunspot numbers, hemispheric sunspot numbers from the new catalogue, total sunspot areas, and hemispheric sunspot areas. For all the data sets, a linear regression based on the maximal growth rate precursor shows a significant correlation. Validation of predictions for cycles 1-24 shows high correlations between the true and predicted cycle amplitudes reaching r = 0.93 for the total sunspot numbers. Furthermore, our findings provide a strong foundation for supporting regular monitoring, recording, and predictions of solar activity with hemispheric sunspot data, which capture the asymmetric behaviour of the solar activity and solar magnetic field and enhance solar cycle prediction methods.