Can strong substorm-associated MeV electron injections be an important cause of large radiation belt enhancements?
Can strong substorm-associated MeV electron injections be an important cause of large radiation belt enhancements?
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DOI：
10.3389/fspas.2023.1128923
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发表时间：
2023-03
期刊：
影响因子：
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通讯作者：
Hee‐Jeong Kim;S. Noh;D. Y. Lee;L. Lyons;J. Bortnik;T. Nagai;W. Choe;M. Hua
中科院分区：
文献类型：
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作者：
Hee‐Jeong Kim;S. Noh;D. Y. Lee;L. Lyons;J. Bortnik;T. Nagai;W. Choe;M. Hua
已经确定的是，强烈的外辐射带增强是由于波驱动的电子被哨声模式的合唱波所激发。然而，在这项研究中，我们检查了2019年7月10日的强MeV电子注入，并发现了大量证据表明这种注入可能是外辐射带增强事件的关键因素。为了进行这样的检查，必须将货车艾伦探测器沿沿着移动时观测到的时间通量变化与空间变化精确地分开。采用一种新的“每小时快照”的分析方法，我们发现了前所未有的细节，电子通量的演变表明，对于这个事件，外带增强不是连续的，而是间歇性的，主要由4个大的离散注入驱动的通量增加。当在远地点附近观测时，注入表现为急剧的通量增加。否则，通过比较不同时间的每小时快照，我们推断注入和注入之间的时间稳定的通量，尽管强烈和连续的合唱发射。快速和间歇性的电子通量增长连续向地球延伸意味着累积的外带增强通过一系列的重复向内传输与注入诱导电场。
It has become well-established that strong outer radiation belt enhancements are due to wave-driven electron energization by whistler-mode chorus waves. However, in this study, we examine strong MeV electron injections on 10 July 2019 and find substantial evidence that such injections may be a crucial contributor to outer radiation belt enhancement events. For such an examination, it is essential to precisely separate temporal flux changes from spatial variations observed as Van Allen Probes move along their orbits. Employing a new “hourly snapshot” analysis approach, we discover unprecedented details of electron flux evolutions that suggest that for this event, the outer belt enhancement was not continuous but instead intermittent, mostly composed of 4 large discrete injection-driven flux increases. The injections appear as sharp flux increases when observed near apogee. Otherwise, by comparing hourly snapshots for different times, we infer injections and infer temporally stable fluxes between injections, despite strong and continuous chorus emission. The fast and intermittent electron flux growth successively extending earthwards implies cumulative outer belt enhancement via a series of repetitive inward transport associated with injection-induced electric fields.