Magnetopause properties at the dusk magnetospheric flank from global MHD simulations, kinetic Vlasov equilibrium and in-situ observations – potential implications for SMILE

We derive the properties of the terrestrial magnetopause (MP) from two modelling approaches, one global-fluid, the other local-kinetic, and compare their results with data collected in-situ by MMS2 spacecraft. We use global MHD simulations of the Earth’s magnetosphere (publicly available from NASA-CCMC) and local Vlasov equilibrium models (based on kinetic models for tangential discontinuities) to extract spatial profiles of the plasma and field variables at the Earth’s magnetopause. The global MHD simulations use initial solar wind conditions extracted from OMNI database at time epoch when MMS2 observes the magnetopause. The kinetic Vlasov model uses asymptotic boundary conditions derived from the same in-situ MMS measurements upstream/downstream the MP. The global MHD simulations provide a 3-D image of the magnetosphere at the time when MMS2 crosses the magnetopause. The Vlasov model provides a 1-D local view of the magnetopause derived from first principles of kinetic theory. The MMS2 experimental data also serve as a reference for comparing/validating the numerical simulations and modelling. We find the magnetopause transition layer formed in global MHD simulations is generally localized closer to the Earth (roughly by one Earth radius) from the position of the real magnetopause observed by MMS. We also find the global MHD simulations overestimate the thickness of the MP transition by one order of magnitude for three analyzed variables: magnetic field, density and tangential speed. The MP thickness derived from local Vlasov equilibrium is consistent with observations for all three variables mentioned above. The overestimation of the density in Vlasov equilibrium is reduced compared to global MHD solutions. We discuss our results in the context of future SMILE campaigns for observing the Earth’s magnetopause.