A comparative study of solar activity parameters during the period 2009–2012 and 2020–2023 (ascending phase of solar cycles 24 and 25)

Abstract

In this paper, we performed solar synodic period (∼27 days) and heliospheric effect for selected solar activity parameters: sunspot number (SSN), sunspot area (SSA), modified coronal index (MCI), solar radio flux (F10.7), chromospheric composite Mg II index and Galactic cosmic rays (GCRs), during the ascending phase of solar cycles 24 and 25 (2009–2012 and 2020 to 2023). The Wavelet analyses of daily data of SSN, SSA, MCI, Mg II, and F10.7, reveal a solar rotational period of ∼27 days. The R Robper method is used to validate the observed periods; near one solar rotational period during the ascending phase of solar cycles 24 and 25. We observed cross-correlation and time lag for solar activity parameters (SSN, SSA, MCI, Mg II, and F10.7) with GCRs during the ascending phase of solar cycles 24 and 25 (2009–2012 and 2020 to 2023). We found the highest time lag for SSA is ∼300 days, and for SSN is ∼270 days during the ascending phase of solar cycle 25. We also found the highest cross-correlation values are 0.998 and 0.996 for chromospheric composite Mg II index with Galactic cosmic rays (GCRs) during the ascending phase of solar cycle 24 and 25 respectively. We found the chromospheric composite Mg II index is a good indicator of solar activity indices and it is strongly correlated to SSN.