Solar Activities and Heliospheric Variations in Cosmic Rays Intensity in Solar Cycle 24

Abstract

Modulations and short-term periodicities in solar activity were analyzed using various proxies, including the solar flare index (FI), cosmic ray intensity (CRI), sunspot area (SSA), sunspot number (SSN), and solar radio flux (F10.7). In Solar Cycle 24, both the maximum phase and the peak activity phase are components of the solar rotational period, representing a non-Rieger-type short-term periodicity. The periodogram and wavelet power spectra of SSN, SSA, F10.7, MCI, FI, and CRI revealed distinct short-term variations. During periods of maximum solar activity, the heliosphere can be affected for up to 27 days. At the peak of Solar Cycle 24, cross-correlation coefficients and temporal delays between CRI and solar activity parameters were computed, with estimated delays of approximately 200 days for SSN, 46 days for SSA, 281 days for MCI, 39 days for FI, and 47 days for F10.7.