Prediction of Amplitude and Timing of Solar Cycle 25

Abstract

We study the geomagnetic activity Ap-index in relation to sunspot number and area for the interval covering Solar Cycles 17 to 24 (1932 – 2019), in view of the availability of data for the Ap-index from 1932 on, in order to predict the amplitude of Sunspot Cycle 25. We examine the statistical relationship between sunspot-maximum amplitude and Ap-index, and similarly that between sunspot area and Ap-index. We apply the $\chi ^{2}$-test for the best fit between two parameters and obtain the correlation coefficient. We also derive the standard deviation for the error limits in the predicted results. Our study reveals that the amplitude of the Sunspot Cycle 25 is likely to be $\approx 100.21 \pm 15.06$ and it may peak in April $2025\pm 6.5$ months. On the other hand, the sunspot area will have maximum amplitude $\approx 1110.62 \pm 186.87$ μ Hem and may peak in February $2025\pm 5.8$ months, which implies that Solar Cycle 25 will be weaker than or comparable to Solar Cycle 24. In view of our results as well as those of other investigators, we propose that the Sun is perhaps approaching a global minimum.