3D Space-Time Adaptive Hybrid Simulations of Magnetosheath High-Speed Jets

Abstract

Abstract We study the generation and evolution of spatially localized dynamic plasma pressure enhancements in the magnetosheath (high-speed jets) by carrying out three-dimensional hybrid simulations of the Earth's dayside magnetosphere with a novel, space-time adaptive code, HYPERS. High-speed jets are shown to occur downstream of quasi-parallel bow shocks under southward and northward quasi-radial interplanetary magnetic field conditions. The physical properties and three-dimensional morphology of simulation jets are found to be consistent with general statistical knowledge acquired from the satellite observations. We discuss a “magnetokinetic” mechanism for jet origin whereby the compression of solar wind plasma and its penetration into the magnetosheath is tied to the turbulence-driven magnetic field perturbations. We compare three-dimensional jets to dynamic pressure structures observed in two-dimensional hybrid simulations and demonstrate the impact of large jets on the magnetopause and the cusp.

Plain Language Summary We present results from two global three-dimensional simulations of the Earth's dayside magnetosphere performed with a novel hybrid code, HYPERS that adaptively selects asynchronous computational updates for electromagnetic fields and kinetic ions on a stretched computational mesh. These simulations are set up with a southward and northward quasi-radial interplanetary magnetic field to provide conditions for the reflecting ions to drive strong turbulence in the magnetosheath (the region of space between the magnetopause and the bow shock). We show that this turbulence creates entangled magnetic field lines. Sporadically moving in the magnetosheath, these field lines “funnel” the solar wind plasma deeper into the magnetosheath, thereby creating compact dynamic pressure enhancements, known as high-speed jets. We show that the properties of simulation jets are generally consistent with the observations. We also compare these jets to dynamic pressure structures generated in two-dimensional hybrid simulations and demonstrate the significant impact of large jets on the magnetopause and the cusp regions of the magnetosphere.