Poleward-moving recurrent auroral arcs associated with impulse-excited standing hydromagnetic waves

查看全文 作　　者：HuaYu [1]Zhao;Xu-Zhi [1]Zhou;Ying [1]Liu;Qiu-Gang [1]Zong;Robert [2]Rankin;YongFu [1]Wang;QuanQi [3]Shi;Xiao-Chen [4]Shen;Jie [1]Ren;Han [1]Liu;XingRan [1]Chen

机构地区：[1]School of Earth and Space Sciences, Peking University, Beijing 100871, China;[2]Department of Physics, University of Alberta, Edmonton, Alberta T6G2J1, Canada;[3]School of Space Science and Physics, Shandong University, Weihai 264209, China;[4]Center for Space Physics, Boston University, Boston, Massachusetts 02215, USA

出　　处：《Earth and Planetary Physics》索引2019年第3卷第4期,共9页

基　　金：supported by the National Natural Science Foundation of China (grant numbers 41774168 and 41421003) 摘　　要：In Earth's high-latitude ionosphere, the poleward motion of east–west elongated auroral arcs has been attributed to standing hydromagnetic waves, especially when the auroral arcs appear quasi-periodically with a recurrence time of a few minutes. The validation of this scenario requires spacecraft observations of ultra-low-frequency hydromagnetic waves in the magnetosphere and simultaneous observations of poleward-moving auroral arcs near the spacecraft footprints. Here we present the first observational evidence from the multi-spacecraft THEMIS (Time History of Events and Macroscale Interactions during Substorms) mission and the conjugated all-sky imager to support the scenario that standing hydromagnetic waves can generate the quasi-periodic appearance of poleward-moving auroral arcs. In this specific event, the observed waves were toroidal branches of the standing hydromagnetic waves, which were excited by a pulse in the solar wind dynamic pressure. Multi-spacecraft measurements from THEMIS also suggest higher wave frequencies at lower L shells (consistent with the distribution of magnetic field line eigenfrequencies), which indicates that the phase difference across latitudes would increase with time. As time proceeds, the enlarged phase difference corresponds to a lower propagation speed of the auroral arcs, which agrees very well with the ground-based optical data. 关键词：poleward-moving auroral ARCS ULF WAVES STANDING HYDROMAGNETIC WAVES field-aligned currents solar wind dynamic pressure pulse

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Poleward-moving recurrent auroral arcs associated with impulse-excited standing hydromagnetic waves

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