Predicting Maximum Amplitude and Rise Time of Solar Cycle 25 Using Modified Geomagnetic Precursor Technique

Abstract

The sun is rapidly approaching towards the pinnacle of its activity in ongoing cycle 25. Solar activity variations cause changes in interplanetary and near-Earth space environment and may deteriorate the operation of space-borne and ground based technological systems (space flights, navigation, radars, high-frequency radio communications, ground power lines, etc.). Scientists predict the exact duration and intensity of each solar cycle based on a variety of methods ranging from purely statistical models using observations of previous cycles to complex simulations of solar physics. In the present study, we utilized the planetary magnetic activity ‘Ap’ index in relation to sunspot activity and sunspot area for the period 1932–2019, covering Solar Cycles 17 to 24, as geomagnetic precursor pair for predicting the maximum amplitude and its time of occurrence for ongoing Cycle 25. The monthly average sunspot data and disturbed days are processed through regression analysis and the obtained analytical results further validated by the observed sunspots of cycle 17 to 24. Hind casting results show close agreement between predicted and observed maximum amplitudes of cycles 17 to 24 to about 10 percent. A multivariate fit using the two best DI indices in variate block 9 also gives the similar correlation to about 0.94 with standard error of estimation (±14). This study divulges that the maximum sunspot number for Solar Cycle 25 is expected to be ≈ 112 ± 18. The probable peak time of cycle 25, after analysis, is found to be 48 ± 3 months. The peak might appear in between October 2023 – April 2024. The obtained results suggest that ongoing cycle akin to the previous Solar Cycle 24 in terms of predicted maximum sunspot numbers.