Specific interplanetary conditions for CIR-, Sheath-, and ICME-induced geomagnetic storms obtained by double superposed epoch analysis

TL;DR

This study uses double superposed epoch analysis to compare interplanetary conditions associated with different types of geomagnetic storms, highlighting the significant role of Sheath regions and differences between magnetic cloud and Ejecta impacts.

Contribution

It introduces a novel application of double superposed epoch analysis to categorize and compare interplanetary drivers of geomagnetic storms, revealing new insights into their properties and effects.

Findings

Sheath regions are highly important in storm generation.

Distinct differences exist between magnetic cloud and Ejecta impacts.

The method allows for standardized comparison of storm main phases.

Abstract

The comparison of specific interplanetary conditions for 798 magnetic storms with Dst < -50 nT for the period 1976-2000 was made on the basis of the OMNI archive data.We categorized various large-scale types of solar wind as interplanetary drivers of storms: corotating interaction region (CIR), Sheath, interplanetary CME (ICME) including magnetic cloud (MC) and Ejecta, separately MC and Ejecta, and "Indeterminate" type. The data processing was carried out by the method of double superposed epoch analysis which uses two reference times (onset of storm and the minimum Dst index) and make a re-scaling of main phase of storm a such way that after this transformation all storms have equal durations of main phase in new time reference frame. This method reproduced some well-known results and allowed us to obtain some new results. Specifically, obtained results demonstrate high importance of Sheath in generation of magnetic storms as well as a significant differences in properties of MC and Ejecta and in their geoeffectiveness.