Electron precipitation from EMIC waves: A case study from 31 May 2013
Electron precipitation from EMIC waves: A case study from 31 May 2013
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DOI：
10.1002/2015ja021090
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发表时间：
2015-05
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影响因子：
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通讯作者：
M. Clilverd;R. Duthie;Rachael L. Hardman;A. Hendry;C. Rodger;T. Raita;M. Engebretson;M. Lessard;D. Danskin;D. Milling
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文献类型：
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作者：
M. Clilverd;R. Duthie;Rachael L. Hardman;A. Hendry;C. Rodger;T. Raita;M. Engebretson;M. Lessard;D. Danskin;D. Milling
2013 年 5 月 31 日，在中/大型地磁暴爆发期间，在磁当地时间下午和晚间区域观察到了几个具有递减周期脉动间隔的升调电磁离子回旋（EMIC）波。芬兰、南极洲和加拿大西部相继观测到了这些波浪。还观测到由地基南极北极辐射带动态沉积甚低频大气研究联盟和测厚仪仪器以及极轨运行环境卫星（POES）电子望远镜组成的网络同时发生的电子降水。与此同时，POES在与地面观测一致的位置检测到30-80 keV质子降水向西漂移，表明存在亚暴注入。通过地面和卫星观测相结合的详细建模，EMIC诱发的电子沉淀的特征被确定为纬度宽度为2-3°或ΔL = 1 Re，纵向宽度~50°或3 h磁本地时间，下截止能量280 keV，典型通量1 × 104 el cm−2 sr−1 s−1 > 300 keV。本研究中最明确定义的 EMIC 上升音调的较低截止能量证实了一类 EMIC 诱发的降水事件的识别，其截止能量出人意料地低于 400 keV。
On 31 May 2013 several rising tone electromagnetic ion cyclotron (EMIC) waves with intervals of pulsations of diminishing periods were observed in the magnetic local time afternoon and evening sectors during the onset of a moderate/large geomagnetic storm. The waves were sequentially observed in Finland, Antarctica, and western Canada. Coincident electron precipitation by a network of ground‐based Antarctic Arctic Radiation‐belt Dynamic Deposition VLF Atmospheric Research Konsortia and riometer instruments, as well as the Polar‐orbiting Operational Environmental Satellite (POES) electron telescopes, was also observed. At the same time, POES detected 30–80 keV proton precipitation drifting westward at locations that were consistent with the ground‐based observations, indicating substorm injection. Through detailed modeling of the combination of ground and satellite observations, the characteristics of the EMIC‐induced electron precipitation were identified as latitudinal width of 2–3° or ΔL = 1 Re, longitudinal width ~50° or 3 h magnetic local time, lower cutoff energy 280 keV, typical flux 1 × 104 el cm−2 sr−1 s−1 > 300 keV. The lower cutoff energy of the most clearly defined EMIC rising tone in this study confirms the identification of a class of EMIC‐induced precipitation events with unexpectedly low‐energy cutoffs of <400 keV.