Magnetohydrodynamic with embedded particle-in-cell simulation of the Geospace Environment Modeling dayside kinetic processes challenge event

TL;DR

This study employs a combined MHD-EPIC simulation to analyze dayside kinetic processes during a GEM event, successfully reproducing observed magnetic and plasma features, including flux ropes and reconnection sites, with insights into X-line dynamics.

Contribution

The paper introduces a coupled MHD-EPIC simulation approach to accurately model dayside magnetopause reconnection and flux rope formation, aligning well with spacecraft observations.

Findings

Simulation reproduces MMS3 observations of magnetic and plasma features.

Multiple X-lines are identified at the magnetopause with moving speeds around 70 km/s.

Flux ropes and reconnection dynamics are effectively captured by the model.

Abstract

We use the MHD with embedded particle-in-cell model (MHD-EPIC) to study the Geospace Environment Modeling (GEM) dayside kinetic processes challenge event at 01:50-03:00 UT on 2015-11-18, when the magnetosphere was driven by a steady southward IMF. In the MHD-EPIC simulation, the dayside magnetopause is covered by a PIC code so that the dayside reconnection is properly handled. We compare the magnetic fields and the plasma profiles of the magnetopause crossing with the MMS3 spacecraft observations. Most variables match the observations well in the magnetosphere, in the magnetosheath, and also during the current sheet crossing. The MHD-EPIC simulation produces flux ropes, and we demonstrate that some magnetic field and plasma features observed by the MMS3 spacecraft can be reproduced by a flux rope crossing event. We use an algorithm to automatically identify the reconnection sites from the simulation results. It turns out that there are usually multiple X-lines at the magnetopause. By tracing the locations of the X-lines, we find the typical moving speed of the X-line endpoints is about 70~km/s, which is higher than but still comparable with the ground-based observations.