[P-EM07] Dynamics in magnetosphere and ionosphere

[PEM07-01] Observations of a viable process for the loss to space of terrestrial atmospheric matter

*Qing-He Zhang¹、Michael Lockwood²、John C. Foster³、Qiu-Gang Zong⁴、Malcolm W. Dunlop⁵、Shun-Rong Zhang³、Brian Walsh⁶、Jøran Moen⁷、Bei-Chen Zhang⁸ (1.Institute of Space Sciences, Shandong University, Weihai, China、2.Department of Meteorology, University of Reading, Earley Gate, Post Office Box 243, RG6 6BB, UK.、3.MIT Haystack Observatory, Westford, MA 01886, USA、4.School of Earth and Space Sciences, Peking University, Beijing, China、5.Space Sciences Division, SSTD, Rutherford Appleton Laboratory, Didcot, UK、6.Mechanical Engineering Department and Center for Space Physics, Boston University, Boston, MA, USA.、7.Department of Physics, University of Oslo, Blindern, Oslo, Norway、8.SOA Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai, China)

キーワード：Plasmaspheric plume, Dayside magnetic reconnection, Particle acceleration

Earth’s atmosphere is protected from direct solar wind erosion by the geomagnetic field. Escape of atmospheric atoms to interplanetary space requires photoionization and subsequent upward ion acceleration to overcome Earth’s gravity. However, these ionospheric ions have not yet escaped the terrestrial environment because the Dungey circulation (convection) keeps most within the inner magnetosphere where they either remain or precipitate back into the atmosphere. Key problems in estimating isotopic loss rates on geological scales are quantifying the fluxes of source upflows and evaluating the fraction that subsequently returns to Earth. We present direct evidence of ionospheric ions making their way, via detached regions from the dusk plasmasphere, into the accelerated flows along the magnetopause generated by magnetic reconnection. Using recently developed techniques to find the transit time of open flux tubes across the polar cap, we show that they gain enough energy to escape from the terrestrial environment into interplanetary space.