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

The present study utilizes the planetary magnetic activity A\(_{\rm p}\) index and the sunspot numbers as geomagnetic precursor pair for predicting the strength of ongoing Cycle 25. The monthly smoothed sunspot number (SSN) and disturbed days (A\(_{\rm p} \geq 25\)), during the post-peak segments of Sunspot Cycles 17 to 24 are processed through regression analysis and the obtained analytical results are validated by comparing with the observed SSN. Hind casting results show close agreement between predicted and observed maximum amplitudes within a confidence limit of up to 10 percent. The obtained results suggest the maximum sunspot number for Solar Cycle 25 to be \(\approx 112 \pm 18\). The probable peak time of Cycle 25 may appear within \(48\pm 3\) months after the commencement of the cycle, i.e., between October 2023 and April 2024.