Evolution of a Foreshock Bubble in the Midtail Foreshock and Impact on the Magnetopause: 3‐D Global Hybrid Simulation

Abstract

AbstractForeshock transients have been observed in the midtail foreshock. How a foreshock transient evolves in nightside foreshock and how it may impact the midtail bow shock, magnetosheath, and magnetopause has not been simulated. In this study, we present three‐dimensional global hybrid simulation results of a foreshock bubble (FB) driven by an interplanetary magnetic field (IMF) rotational discontinuity. As the FB propagates in the nightside foreshock, its spatial size grows to >10 RE, and its density and dynamic pressure perturbations are enhanced by >50% of the solar wind values. As the FB interacts with the nightside bow shock, the bow shock is temporarily eroded, and the corresponding dynamic pressure perturbations in the magnetosheath penetrate deep to the magnetopause, causing localized distortion of the magnetopause shape. As the FB moves tailward, it continuously generates new perturbations in the magnetosheath and magnetopause following FB's propagation.