Nightside Ionospheric Convection Asymmetries During the Early Substorm Expansion Phase: Relationship to Onset Local Time
Nightside Ionospheric Convection Asymmetries During the Early Substorm Expansion Phase: Relationship to Onset Local Time
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DOI：
10.1002/2017gl075763
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发表时间：
2017-12
影响因子：
5.2
通讯作者：
A. Grocott;H. Laurens;J. Wild
中科院分区：
文献类型：
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作者：
A. Grocott;H. Laurens;J. Wild
我们提出了超级双极光雷达网在亚暴期间对电离层对流的观测。亚暴根据其起始纬度、起始磁地方时和行星际磁场（IMF）盛行感BY进行分组。然后，根据产生的亚暴群和平均对流模式对雷达观测进行分类。在这里，我们讨论发生在65°-67°起始纬度范围内的亚暴的模式，发生在地磁时的早（20-22小时）或晚（01-03小时），在主导的IMF BY为正或负的时间间隔内。我们发现对流模式的形态与现有经验模型预测的不同，夜侧对流喉部的位置与亚暴发生的位置基本一致。当亚暴发生在一个偶然的位置时，预期的IMF BY诱导的黎明-黄昏对流不对称可以在夜侧得到增强，但同样可以从这种预期状态中移除甚至逆转。因此，夜侧对流的不对称似乎与IMF BY的瞬时感无关。
We present Super Dual Auroral Radar Network observations of ionospheric convection during substorms. Substorms were grouped according to their onset latitude, onset magnetic local time, and the prevailing sense of interplanetary magnetic field (IMF) BY. The radar observations were then sorted according to substorm group and average convection patterns produced. Here we discuss the patterns corresponding to substorms with onsets occurring in the 65∘–67∘ onset latitude range, at either early (20–22 h) or late (01–03 h) magnetic local times, during intervals of either dominant positive or negative IMF BY. We show that the morphology of the convection patterns differs from that predicted by existing empirical models, with the location of the nightside convection throat being largely consistent with the location of substorm onset. The expected IMF BY‐induced dawn‐dusk convection asymmetry can be enhanced on the nightside when the substorm onset occurs at a fortuitous location but can equally be removed or even reversed from this expected state. Thus, the nightside convection asymmetries are seemingly unrelated to the instantaneous sense of IMF BY.