Study of Evolution and Geo-effectiveness of CME-CME Interactions using MHD Simulations with SWASTi framework

TL;DR

This study uses 3D MHD simulations with the SWASTi framework to analyze CME-CME interactions and their effects on space weather, revealing how interactions influence geomagnetic storm intensity and structure.

Contribution

It introduces a comprehensive simulation approach to study CME-CME interactions under realistic solar wind conditions, highlighting their impact on geomagnetic disturbances.

Findings

CME-CME interactions vary along different longitudes due to solar wind inhomogeneity.

Collisions increase the momentum and energy of the leading CME.

Reverse shocks form during strong interactions, affecting storm recovery.

Abstract

The geo-effectiveness of Coronal Mass Ejections (CMEs) is a critical area of study in space weather, particularly in the lesser-explored domain of CME-CME interactions and their geomagnetic consequences. This study leverages the SWASTi framework to perform 3D MHD simulation of a range of CME-CME interaction scenarios within realistic solar wind conditions. The focus is on the dynamics of the initial magnetic flux, speed, density, and tilt of CMEs, and their individual and combined impacts on the disturbance storm time (Dst) index. Additionally, the kinematic, magnetic, and structural impacts on the leading CME, as well as the mixing of both CMEs, are analyzed. Time series in-situ studies are conducted through virtual spacecraft positioned along three different longitudes at 1 AU. Our findings reveal that CME-CME interactions are non-uniform along different longitudes due to the inhomogeneous ambient solar wind conditions. A significant increase in the momentum and kinetic energy of the leading CME is observed due to collisions with the trailing CME, along with the formation of reverse shocks in cases of strong interaction. These reverse shocks lead to complex wave patterns inside CME2, which can prolong the storm recovery phase. Furthermore, we observed that the minimum Dst value decreases with an increase in the initial density, tilt, and speed of the trailing CME.