Accepted Paper


Geoeffectiveness of Halo, Non-Halo and Partial Halo Coronal Mass Ejections in Solar Cycle 25 (2020--2024)

Nisha Kohli1, Suman Garia1, Geeta Brithwal2
1Department of Physics, S.S.M.M.U.S.S.S. Govt. P.G. College, Dwarahat -263653, Almora, Uttarakhand, India
2Department of Physics, Soban Singh Jeena University, Almora, Pt. B.D. Pandey Campus, Bageshwar 263642, Uttarakhand, India
Abstract. Coronal mass ejections (CMEs) are key drivers of geomagnetic storms (GSs) that significantly impact Earth's magnetosphere and space weather. Analyzing 701 CMEs observed during Solar Cycle 25 (2020-2024), classified by propagation speed and angular width, this study reveals that CME speed, angular width, and flare class alone do not reliably predict GS intensity. Among 142 fast CMEs (≥ 1000 km/s) including halo, partial-halo, and non-halo types and 559 slower CMEs, the strongest storm (Dst = -406 nT) followed interacting halo CMEs, highlighting the importance of CME-CME interactions. Weak correlations between CME kinematics (∣r∣ ≤ 0.31) and Dst, alongside frequent intense storms from moderate or even flare-less events, emphasize the dominant role of the interplanetary magnetic field (IMF) orientation especially sustained southward Bz components and CME trajectory. Narrow and non-halo CMEs also generate strong geomagnetic responses under favorable IMF conditions. These findings underscore the necessity of multi-parameter forecasting approaches integrating CME kinematics, magnetic structure, and geometry to enhance geomagnetic storm prediction accuracy.

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