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<p>During Solar Cycle 23, a detailed analysis was conducted to identify the interplanetary drivers of severe geomagnetic storms (Dst ≤ − 150 nT) and to investigate their dependence on solar cycle phases. All such storms were associated with prolonged intervals of southward interplanetary magnetic field (IMF Bz), emphasizing magnetic reconnection as the dominant triggering mechanism. Using OMNI data, key interplanetary parameters (B, Bz, Vsw, Dsw, Tsw) and geomagnetic indices (Kp, Ap, SYM-H) were examined, along with solar proxies (Sunspot Number, SSN; and solar radio flux, F10.7). The results indicate that most severe storms were driven by four primary interplanetary structures: magnetic clouds with shocks (sMC, 30.4%), sheath fields (Sh, 30.4%), combined sheath–magnetic cloud events (Sh + MC, 17.4%), and non-magnetic cloud ICMEs (non-MC, 17.4%), with complex structures contributing only 4.3%. Together, these accounted for roughly 75% of all severe storms during Solar Cycle 23. In terms of solar cycle dependence, sMCs and sheaths were the most frequent drivers during the rising phase, sheath fields dominated during solar maximum, and sMCs, sheaths, and CIRs were the primary contributors during the declining phase. The analysis further confirms that interplanetary magnetic field strength (B, Bz) and solar wind conditions (Vsw, Dsw, Tsw) are more directly responsible for storm intensity than solar proxies (SSN, F10.7), reinforcing the importance of interplanetary monitoring for space weather forecasting.</p>

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Investigating the interplanetary causes of severe geomagnetic storms during solar cycle 23 using SYM-H and OMNI data

  • 期刊论文

  • 发表日期：

    2026年1月9日

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  • Saket Kumar,
  • Swapnil Garg,
  • Palak Singh Takur,
  • Shrish Lata Soni,
  • O. P. Tripathi

摘要

During Solar Cycle 23, a detailed analysis was conducted to identify the interplanetary drivers of severe geomagnetic storms (Dst ≤ − 150 nT) and to investigate their dependence on solar cycle phases. All such storms were associated with prolonged intervals of southward interplanetary magnetic field (IMF Bz), emphasizing magnetic reconnection as the dominant triggering mechanism. Using OMNI data, key interplanetary parameters (B, Bz, Vsw, Dsw, Tsw) and geomagnetic indices (Kp, Ap, SYM-H) were examined, along with solar proxies (Sunspot Number, SSN; and solar radio flux, F10.7). The results indicate that most severe storms were driven by four primary interplanetary structures: magnetic clouds with shocks (sMC, 30.4%), sheath fields (Sh, 30.4%), combined sheath–magnetic cloud events (Sh + MC, 17.4%), and non-magnetic cloud ICMEs (non-MC, 17.4%), with complex structures contributing only 4.3%. Together, these accounted for roughly 75% of all severe storms during Solar Cycle 23. In terms of solar cycle dependence, sMCs and sheaths were the most frequent drivers during the rising phase, sheath fields dominated during solar maximum, and sMCs, sheaths, and CIRs were the primary contributors during the declining phase. The analysis further confirms that interplanetary magnetic field strength (B, Bz) and solar wind conditions (Vsw, Dsw, Tsw) are more directly responsible for storm intensity than solar proxies (SSN, F10.7), reinforcing the importance of interplanetary monitoring for space weather forecasting.