International Journal of Science, Engineering and TechnologyAuthors: Rekha Agarwal, Rajesh Kumar Mishra, Divyansh Mishra
Abstract: Solar Cycle 25 (SC25), the most energetically active solar cycle in approximately two decades, has produced a remarkable sequence of solar events that have profoundly modulated the flux of high-energy cosmic ray (CR) particles near Earth. This paper presents a systematic, multi-instrument analysis of the effects of recent SC25 events — including five Ground-Level Enhancements (GLEs), extreme Forbush Decreases (FDs), and an Anisotropic Cosmic-Ray Enhancement (ACRE) — on high-energy galactic cosmic rays (GCRs) and solar energetic particles (SEPs) detected by the global neutron monitor (NM) network, the SEVAN multi-directional detector, and space-based platforms. We reconstruct the differential rigidity spectra of SEPs during GLE73–GLE77, characterise the rigidity-dependent amplitude of major FDs across stations spanning Rc = 0.01–13 GV, and demonstrate a fundamental spectral asymmetry between GLE enhancements (hard SEP component concentrated at R ~ 1–4 GV) and FD suppressions (selectively removing the softer GCR component below ~5 GV). GLE74 (11 May 2024), embedded within the largest FD of SC25 (−15.7% at Oulu NM, 10 GV rigidity) and a G5 geomagnetic storm, exhibited a moderately soft spectrum (γ ≈ 5.0–6.3) with a spectral rollover above ~2 GV and an unusually broad angular distribution indicative of pitch-angle scattering in the highly disturbed heliospheric field. GLE77 (11 November 2025), the strongest event in 19 years, displayed a harder spectrum (γ ≈ 4.5–5.0) and a characteristic double-peak structure attributable to distinct flare-impulsive and CME-shock-accelerated particle populations, confirmed by the first simultaneous gamma-ray detection at both Arctic and Antarctic polar stations. The ACRE event of 5 November 2023 — only the third known event of its kind and the first detected to 8 GV midrigidity — demonstrates that complex heliospheric magnetic configurations can focus and intensify high-energy GCRs from the anti-Sun direction at energies above 10 GeV. These findings collectively advance the physical understanding of CR acceleration, transport, and modulation in the inner heliosphere during a strong solar maximum and carry direct implications for radiation protection in aviation, human spaceflight, and space weather operations.
