GEM: Cold Dense and/or Heavy Plasma Controlling the Magnetopause Dynamics

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The effects of oxygen ions, flowing out of the ionosphere, on the processes that allow mass, energy, and momentum from the solar wind to penetrate into the magnetosphere is an open question of critical importance in understanding the way the Geospace system works to protect the Earth. This is also a critical element affecting how space weather disturbances are generated in our vicinity. The Geospace system is composed of: (1) the upper regions of our atmosphere, (2) the ionosphere (which is an embedded layer of ions within this region), and (3) the magnetosphere (which is the extension of the Earth's magnetic field into space). The solar wind is the hot upper atmosphere of the sun, which gravity is unable to contain, blowing outward carrying with it solar magnetic fields. Only a few percent of the energy in the solar wind actually leaks into the magnetosphere, which acts as a magnetic shield, but this is enough to power severe space weather disturbances near the Earth. One way solar wind mass and energy leaks into the magnetosphere is through magnetic reconnection which is, essentially, the breaking of the Earth's magnetic field lines and joining with the interplanetary magnetic field lines, accompanied by explosive energy releases. In another process, solar wind momentum and mass are transmitted across the magnetopause through large vortices (called Kelvin-Helmholtz waves) that develop at the interface between the fast solar wind and the much slower magnetospheric plasma. However during disturbed space weather conditions, heated ionospheric oxygen ions flow outward and mix with the hotter more tenuous hydrogen ions in the dayside magnetosphere. Their presence alters the conditions for magnetic reconnection and for the formation of Kelvin-Helmholtz waves. This modulates the entry of the solar wind in unknown ways. This project will combine a coordinated set of spacecraft and ground-based observations with global models to investigate how these processes change in the presence of cooler denser ionospheric-origin oxygen ions and what controls the amount of these oxygen ions that reach the magnetosphere. New knowledge about how the Geospace system works is expected to result from this investigation. The broader impacts are significant including: the further training of a postdoctoral researcher who is also a co-I on the project, the support of two female scientists (one being the PI), which contributes to diversity in the field, and a plan for participating in outreach activities involving high school and undergraduate students. Knowledge gained from this work will also be of interest to researchers studying solar system, astrophysical and laboratory plasmas and will in the long-term be an important component in improving the ability to forecast space weather disturbances of importance to society.The methodology of the study will combine both statistical and case studies of coordinated observations that connect the dayside magnetopause with outflows from the upper ionosphere or plasmaspheric drainage plumes from the inner magnetosphere. The coordinated observations of magnetosphere and ionosphere parameters will be taken from the MMS, THEMIS, Cluster, Van Allen Probes, DMSP, and FAST satellite datasets; solar wind parameters from ACE and Wind satellites upstream of the Earth; and information on the magnetopause/magnetosphere from ground-based observations including magnetograms, radar and all-sky imagers. Simulations of the global magnetosphere will be used to aid in interpreting the observations.