North–south asymmetry in solar activity and Solar Cycle prediction, V: prediction for the north–south asymmetry in the amplitude of Solar Cycle 25

Abstract

We analyzed the daily sunspot-group data reported by the Greenwich Photoheliographic Results (GPR) during the period 1874-1976 and Debrecen Photoheligraphic Data (DPD) during the period 1977-2017, and the revised Version-2 of ISSN during the period 1874-2017. We determined the amplitude of the Solar Cycles 12-24 and the 13-month smoothed monthly mean corrected areas of the sunspot groups in the Sun's whole-sphere (WSGA), northern hemisphere (NSGA), and southern hemisphere (SSGA) at the epochs of the maxima of the Solar Cycles 12-24. Using all these we obtained the relations similar to that found in our earlier analyzes -- i.e., the existence of a high correlation between the sum of the areas of sunspot groups in the southern-hemisphere near-equatorial band during a small interval (7-9 months) just after a maximum epoch of a solar cycle and the amplitude of next solar cycle -- separately for the Sun's whole-sphere and northern- and southern-hemispheres. By using these relations we predicted ~701 msh (millionth of solar hemisphere), ~429 msh, and ~366 msh for the values of WSGA, NSGA, and SSGA, respectively, at the maximum epoch of the Solar Cycle 25. We predicted 86 + or - 18 for the amplitude of Solar Cycle 25. The 13-month smoothed monthly mean sunspot-group area highly correlate with that of ISSN. Using this relation and the predicted values of WSGA, NSGA, and SSGA we have obtained 68 + or -11 for the amplitude of Solar Cycle 25, which is slightly lower than the aforementioned predicted value, and 39 + or - 4 and 31 + or - 6 for the values of northern- and southern-hemispheres' sunspot numbers at the maximum epoch of Solar Cycle 25. Overall, our results suggest that the amplitude of Solar Cycle 25 would be 25%-40% smaller, and the corresponding north-south asymmetry would be much smaller, than those of Solar Cycle 24.