Multiscale Observation of Two Polar Cap Arcs Occurring on Different Magnetic Field Topologies
Multiscale Observation of Two Polar Cap Arcs Occurring on Different Magnetic Field Topologies
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DOI：
10.1029/2019ja027611
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发表时间：
2020-08
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影响因子：
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通讯作者：
J. Reidy;J. Reidy;R. Fear;D. Whiter;B. Lanchester;A. Kavanagh;Daniel J. Price;J. Chadney;Yongliang Zhang;L. Paxton
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文献类型：
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作者：
J. Reidy;J. Reidy;R. Fear;D. Whiter;B. Lanchester;A. Kavanagh;Daniel J. Price;J. Chadney;Yongliang Zhang;L. Paxton
本文介绍了极冠弧子结构的观测，尺度可达米，时间分辨率可达毫秒。两个案例研究包含极地帽弧发生在斯瓦尔巴特群岛。第一次发生在2016年2月4日，与闭合磁力线上的地层一致;第二次发生在2015年12月15日，与开放磁力线上的地层一致。这些事件是使用国防气象卫星计划（DMSP）航天器上的特殊传感器紫外光谱成像仪（SSUSI）仪器的全球范围图像识别的。当弧通过位于斯瓦尔巴特群岛的极光结构和动力学（ASK）仪器的小尺度视场时，然后使用来自也位于斯瓦尔巴特群岛的相机的所有天空图像找到了时间间隔。这些观测为小规模极冠弧结构提供了前所未有的见解。结合南安普顿电离层模式，利用ASK观测资料对这些弧上方的沉降粒子的能量和通量进行了估算。然后将这些估计值与现场DMSP粒子测量以及地面仪器的数据进行比较，以推断有关其形成机制的进一步信息。本文发现，在不同的磁场拓扑结构上形成的极帽弧在小尺度上表现出不同的行为，与它们各自的形成机制一致。
This paper presents observations of polar cap arc substructure down to scale sizes of meters and temporal resolution of milliseconds. Two case studies containing polar cap arcs occurring over Svalbard are investigated. The first occurred on 4 February 2016 and is consistent with formation on closed field lines; the second occurred on 15 December 2015 and is consistent with formation on open field lines. These events were identified using global‐scale images from the Special Sensor Ultra‐violet Spectrographic Imager (SSUSI) instruments on board Defense Meteorological Satellite Program (DMSP) spacecraft. Intervals when the arcs passed through the small‐scale field of view of the Auroral Structure and Kinetics (ASK) instrument, located on Svalbard, were then found using all sky images from a camera also located on Svalbard. These observations give unprecedented insight into small‐scale polar cap arc structure. The energy and flux of the precipitating particles above these arcs are estimated using the ASK observations in conjunction with the Southampton Ionospheric model. These estimates are then compared to in situ DMSP particle measurements, as well as data from ground‐based instrumentation, to infer further information about their formation mechanisms. This paper finds that polar cap arcs formed on different magnetic field topologies exhibit different behavior at small‐scale sizes, consistent with their respective formation mechanisms.