This study presents a statistical investigation of Forbush decrease (FD) events and their association with solar and interplanetary drivers, particularly coronal mass ejection (CMEs) and solar flare activity. The results show that a dominant fraction of FD events (70 events; 88.57%) are associated with halo and partial-halo CMEs, confirming that Earth-directed CME structures play a key role in the generation of FD events. Among these, 54 events (77.14%) correspond to halo CMEs, while 8 events (11.42%) are linked to partial-halo CMEs.
A moderate positive correlation (r = 0.43) is observed between FD magnitude and CME speed, indicating that faster CMEs tend to produce stronger cosmic ray depressions at Earth. Importantly, all analyzed FD events (100%) are associated with solar X-ray flares of varying classes, establishing a universal flare connection. The flare distribution is dominated by M-class flares (37 events; 52.85%), followed by X-class flares (17 events; 24.28%), C-class flares (15 events; 21.42%), and a minor contribution from B-class flares (1 event; 1.42%). These findings collectively highlight that energetic, Earth-directed CMEs accompanied by significant flare activity are the primary drivers of FD events and play a crucial role in space weather modulation.
KEYWORDS
Forbush Decrease, Coronal Mass Ejection, Halo CME, Solar Flare, CME Speed.
Ajay Kumar Saket1*, Nand Kumar Patel2
1Research Scholar PM Excellence, Chhatrasal Govt. P. G. College, Panna- 488001, M.P., India
2Department of Physics PM Excellence, Chhatrasal Govt. P. G. College, Panna- 488001, M.P., India