Magnetopause properties from global MHD numerical simulations, local Vlasov equilibrium models and in-situ observations

We derive the properties of the terrestrial magnetopause (MP) from two modelling approaches, one global-fluid/MHD, the other local-kinetic,  as well as from in-situ data analysis. 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 across the Earth’s magnetopause. We use data from MMS spacecraft to probe in-situ the properties of the magnetopause. The experimental data also serve as a reference for comparing/validating the numerical simulations. The global MHD simulations use initial conditions in the solar wind extracted from OMNI database at time epoch when MMS crossed the magnetopause. The kinetic Vlasov model uses boundary conditions derived from the same in-situ MMS measurements upstream/downstream the MP. We find  the global MHD simulations generally locate the MP at distances of one Earth radius farther from the position observed by MMS. We also find an overestimation of  the  thickness of the MP by one order of magnitude, as well as of the plasma density in the vicinity of the magnetopause. The MP spatial scale derived from local Vlasov equilibrium is consistent with observations for three transition profiles (magnetic field, plasma density, plasma bulk velocity). The overestimation of the density in Vlasov equilibrium is reduced compared with global MHD solutions. We discuss our results in the context of future SMILE mission campaigns for observing the Earth’s magnetopause.