Abstract

This study examines the role of the southward interplanetary magnetic field component (Bz < –10 nT) as a driver of geomagnetic super-storms during Solar Cycle 23 (1996–2008). Super-storms were defined by a Disturbance Storm Time (Dst) index of less than –250 nT. Using hourly Dst data from the World Data Center for Geomagnetism, Kyoto, and corresponding Bz values from OMNIWeb, 63 super-storm events were identified. Pearson correlation analysis was used to assess the relationship between Bz and Dst. Across the full dataset of 113,978 observations, the correlation coefficient was r = 0.0053 (p = 0.0700), indicating no significant linear relationship. Similarly, the case was the same for the 63 super-storm events, r = 0.0150 (p = 0.9071). These results suggest that Bz does not show a strong linear correlation with Dst values, even during severe geomagnetic disturbances. However, 59% (37 out of 63) of super-storms occurred when Bz < –10 nT, highlighting a strong association between southward Bz and storm intensity. This suggests Bz is a more consistent indicator of super-storm occurrence than sunspot number, which showed no reliable correlation. The study shows the importance of monitoring Bz for space weather forecasting and recommends future research across other solar cycles, including other solar wind parameters, to improve predictive models.

Key words: super-storms, Dst index, Bz, SC 23