Using a Magnetohydrodynamic (MHD) Model to Simulate the Magnetospheric Response to a Kinetic Foreshock Transient

Abstract A global magnetohydrodynamic model predicts the response of the magnetosphere to the passage of a foreshock transient. We simulate the transient as an antisunward‐ and dawnward‐moving slab of hot tenuous solar wind plasma and weak magnetic field strengths on magnetic field lines connected to the bow shock. The slab elicits large‐amplitude outward bow shock motion with a stronger jump in plasma and magnetic field parameters on the trailing than the leading edges of this motion. The outward bulge in the bow shock bounds a magnetosheath region containing a hot tenuous plasma with weakened magnetic field strengths and flows deflected away from the Sun‐earth line. The magnetopause bulges outward into this magnetosheath region to distances beyond the nominal bow shock. Despite the large amplitude magnetopause motion, perturbations at geosynchronous orbit are miniscule. Model predictions compare well to the observed characteristics of foreshock transients and their effects on the magnetosphere.