How does the planetary bow shock at earth process ICME shock, sheath, and ejecta? An MHD simulation event study.

Authors: Austin Brenner (University of Michigan), Matti Ala-Lahti (University of Michigan), Tuija Pulkkinen (University of Michigan)

When an interplanetary coronal mass ejection impacts the earth’s bow shock it can have severe consequences for human interests on the planet. In order to better understand the consequences of kinetic scale phenomena in collisionless shock wave physics we must also consider the macro scale dynamics. In this study we use MHD simulation results of real ICME impact events on Feb 2014 and May 2019 to investigate how the bow shock at earth responds to and processes the shock, sheath, and ejecta portions of the ICME. The bow shock location is determined via local MHD variables, comparing the local specific entropy to a free stream value. The properties changing across the shock are taken via flow field tracing at various locations at the identified shock surface. Finally Cluster and Geotail observations are used to check the simulation results for bow shock position and characteristics.