Magnetosheath dynamic pressure enhancements associated with a solar wind rotational discontinuity: Results from a hybrid-Vlasov simulation

When plasma and magnetic field discontinuities in the solar wind interact with Earth’s magnetic field, they can significantly alter the properties and dynamics of Earth’s bow shock, magnetosheath, and magnetopause. In this study, we investigate magnetosheath dynamic pressure enhancements generated by the interaction between a solar wind rotational discontinuity with Earth’s bow shock in a 2D simulation run of the global magnetospheric hybrid-Vlasov model Vlasiator. We find that as the discontinuity is advected into the bow shock, several fast-mode pulses associated with enhanced dynamic pressure are launched toward the Earth. In addition, the interaction between discontinuity and shock generates transient enhancements of dynamic pressure at the bow shock that move Earthward together with the discontinuity. We find that the fast-mode pulses are able to traverse the magnetosheath and disturb the magnetopause. This finding differs from the results of previous studies using 2D and 3D MHD simulations as well as spacecraft measurements, which concluded that magnetopause disturbances should be caused by the rotational discontinuity itself and the dynamic pressure enhancement associated with it.