Geo-effectiveness of ICMES/MCs of different magnetic-polarity configurations

Abstract

This research investigates the geoeffectiveness of interplanetary magnetic field configurations by analyzing 203 geomagnetic storm events recorded between 1995 and 2015. The study systematically categorizes events into five intensity levels: quiet, weak, moderate, intense, and severe, to evaluate how different polarity configurations and flux rope configurations influence geomagnetic activity. Utilizing an extensive methodology, we employed correlation analysis and superposed epoch analysis on 17 parameters extracted from OMNI/NASA hourly datasets. The investigation focused on identifying how specific magnetic configurations impact geomagnetic storm characteristics, with special attention to the Disturbance Storm-Time Index (Dst). The findings reveal nuanced variations in geoeffectiveness across magnetic configurations. Configurations were stratified into two primary groups, with Group 1 (S, SN, SNN, SNS) demonstrating notably higher geomagnetic responsiveness. Notably, the SNS configuration emerged as the most geoeffective, accounting for 37% of intense storms and exhibiting an extended main phase lasting 48 hours. Conversely, Group 2 configurations (N, NS, NSS, NSN) generally displayed reduced geoeffectiveness, contributing to 30% of quiet storms and merely 3% of severe storms. However, the NSS configuration presented an intriguing anomaly, characterized by the lowest negative Dst value and an unprecedented 96-hour recovery phase, attributed to its distinctive two-step main phase storm. Flux rope configurations also demonstrated differential impacts, with the \(F^{+}\) rotation being particularly geoeffective, contributing to 11% of severe storms. We further uncovered a remarkably strong correlation between the dawn-dusk electric field (Ey) and \(Dst_{min}\) in the NSS configuration, registering a correlation coefficient of -0.95.