GEM: Solar Wind Entry into the Magnetospohere and Its Paths to the Plasma Sheet

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How and where plasma from the solar wind enters Earth's magnetosphere is still largely unknown. This project will use a combination of state-of-the-art global hybrid (kinetic ions, fluid electrons) simulations and comparison with spacecraft data to address this problem. The project has two phases. The first concerns the entry of plasma into the magnetosphere on the dayside magnetopause, while the second concerns phenomena that occur on the magnetotail flanks and the processes that transfer incoming solar wind plasma into the plasma sheet. Initially, the focus will be on issues such as the influences of the bow shock, ion foreshock and magnetosheath on dayside transport during steady and non-steady solar wind conditions. Formation of low latitude (LLBL) and high latitude (HLBL) boundary layers and their structure will be investigated. Next, the transport of the boundary layer plasma will be followed to assess its contributions to the plasma sheet population. In addition, direct entry mechanisms into the plasma sheet through the tail lobes and flanks will be investigated. The proposed modeling and spacecraft data analysis activities are designed to take advantage of the strength of each approach and achieving a synergy that will lead to an understanding of solar wind entry into the magnetosphere and its paths to the plasma sheet. By virtue of resolving ion temporal and spatial scales, global hybrid simulations are uniquely suited for addressing plasma transport questions such as the relative significance of reconnection and wave-particle interactions or local vs. non-local processes. In addition to the basic plasma moments (density, flow speed etc.), hybrid simulations will provide ion velocity distribution functions throughout the magnetosphere. The kinetic treatment of ions makes it possible to investigate mass filtering effects at the magnetopause and to trace the orbit of ions in a self consistent manner.