Study of the Interplanetary Coronal Mass Ejection (ICME) Disturbances of Different Structure Types between 1995 and 2022 and Their Relative Geoeffectiveness: Superposed Epoch Analysis

Abstract

This study presents an analysis of the solar wind plasma and field parameters and geomagnetic indices response to 255 events between 1995 and 2022 with Disturbance storm time Dst ≤ –30 nT. The events were divided into nine groups and structures. Superposed epoch analysis was performed on the selected events to study the effect based on each group. We also performed a correlation analysis between geomagnetic indices, solar wind plasma and field parameters. We found that Dst has a strong correlation with Planetary Kp index (Ap) and a moderate correlation with Auroral Electrojet index (AE), while ap has a strong correlation with Dst and AE. Duskward electric field (Ey) is consistently better related to all three geomagnetic indices (Dst, Ap and AE), Dst relation is relatively stronger with Bz than Ey. Other two indices (Ap and AE) correlation is relatively weaker with Bz than Ey. In addition to Ey, another interplanetary parameter, the interplanetary electric field (BV), correlates reasonably well with the Ap and AE indices. Thus, Ey can be universally used as coupling function in all three domains (equatorial, mid-latitude and polar), represented by Dst, Ap, and AE indices, respectively. However, Bz in the equatorial, and BV in the mid-latitude and equatorial regions, may also be considered as alternate coupling functions. Best-fit linear equations obtained between geomagnetic indices and best-related field parameters can be utilized to estimate the expected strength of geomagnetic disturbances in the equatorial, mid-latitude and polar regions using plasma/field observations during passage of ICME associated structures. Furthermore, we investigated the recovery phase of each parameter within each group. We observed a strong correlation between the time constants of the geomagnetic indices, both amongst themselves and with Bz.