Magnetosheath Effects in Solar Wind - Magnetosphere Coupling Processes

Abstract:

Magnetic reconnection at the magnetopause is the dominant process allowing energy entry from the solar wind into the magnetosphere especially during southward IMF periods. Before reaching the magnetopause, the solar wind plasma transits through a bow shock, which decelerates the plasma and changes the magnetic field magnitude and orientation, and thus the local reconnection geometry. Differences of the shock physics in the quasi-parallel and quasi-perpendicular side cause asymmetries in the magnetosheath plasma that impacts the coupling processes at the magnetopause. Fluctuations in the magnetic field or plasma density and velocity can also contribute to the efficiency of the energy transfer processes both during southward and northward IMF conditions. We use the OMNI measurements in the solar wind and ionosphere together with the THEMIS observations in the magnetosheath to study the effects of the magnetosheath processes and IMF and velocity fluctuations on the energy and plasma input into the magnetosphere. MHD simulations both in global and local scales complement the observational analyses, which allow us to draw more quantitative conclusions and develop understanding of the underlying physics.