Observation and modeling of the injection observed by THEMIS and LANL satellites during the 23 March 2007 substorm event
Observation and modeling of the injection observed by THEMIS and LANL satellites during the 23 March 2007 substorm event
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DOI：
10.1029/2008ja013498
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发表时间：
2009
影响因子：
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通讯作者：
Wenlong Liu;Xinlin Li;T. Sarris;C. Cully;R. Ergun;V. Angelopoulos;D. Larson;A. Keiling;K. Gla
中科院分区：
文献类型：
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作者：
Wenlong Liu;Xinlin Li;T. Sarris;C. Cully;R. Ergun;V. Angelopoulos;D. Larson;A. Keiling;K. Gla
[1]在2007年3月23日遭遇亚暴期间，THEMIS星座观测到午夜前扇区的高能粒子注入和双极化。在11 RE和当地时间（LT）2100左右的区域，在三个探头（A、B和D）的主增强期间观察到清晰的注入和偶极特征。THEMIS C在8.3 RE的星座中处于领先地位，也观察到了清晰的注入特征，但双极化并不那么清晰。根据这些观测的时间，确定了一个快速向西扩展的离子注入和双极化前沿。结合从洛斯阿拉莫斯国家实验室（LANL）地球同步卫星的高能粒子观测，粒子注入似乎开始之间2100和0100 LT。这一事件提供了一个很好的机会，研究地球同步轨道以外的偶极和粒子注入过程，并在广泛的LT范围。我们通过测试粒子模拟来模拟这种注入事件，设置初始粒子分布，并从也在方位角上扩展的尾部向地球发送类似偶极的脉冲，然后记录各个卫星位置的离子和电子。试验粒子模拟再现了注入粒子的大部分特征。这些因素不仅包括向地球的注入，还包括注入的快速向西扩张，以及在进行观测的不同卫星之间观察到的注入时间。观测和模拟结果的基础上，我们认为，这个亚暴注入开始约2300 LT，更远的尾巴，径向向内传播和扩大的方位角。
[1] During the encounter of a substorm on 23 March 2007, the THEMIS constellation observed energetic particle injections and dipolarizations in the premidnight sector. Clear injection and dipolarization signatures were observed during the main intensification by three probes (A, B, and D) in the region around 11 RE and 2100 local time (LT). THEMIS C, which was leading in the constellation at 8.3 RE, also observed a clear injection signature, but the dipolarization was not so clear. From the timing based on these observations, a fast westward expanding ion injection and dipolarization front was identified. In combination with the energetic particle observations from Los Alamos National Laboratory (LANL) geosynchronous satellites, the particle injection seemed to initiate between 2100 and 0100 LT. This event provides an excellent opportunity to examine the dipolarization and particle injection processes beyond geosynchronous orbit and over a wide LT range. We model this injection event by means of test particle simulation, setting up an initial particle distribution and sending an earthward dipolarization-like pulse from the tail that also expands azimuthally, then recording the ions and electrons at the various satellite locations. Most features of the injected particles are reproduced by the test particle simulation. These include not only the earthward injections but also the fast westward expansion of the injection, as well as the timing of the injections as observed among different satellites that made the observations. On the basis of the observations and the simulation results, we suggest that this substorm injection was initiated around 2300 LT, farther down the tail, and propagated radially inward and expanded azimuthally.