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Dynamics of Variable Dusk-Dawn Flow Associated with Magnetotail Current Sheet Flapping
Annales Geophysicae ( IF 1.9 ) Pub Date : 2021-06-03 , DOI: 10.5194/angeo-2021-32
James Henry Lane , Adrian Grocott , Nathan Anthony Case , Maria-Theresia Walach

Abstract. Previous observations have provided a clear indication that the dusk-dawn (v⊥y) sense of both slow (< 200 km s−1) and fast (> 200 km s−1) convective magnetotail flows is strongly governed by the Interplanetary Magnetic Field (IMF) By conditions. The related “untwisting hypothesis” of magnetotail dynamics is commonly invoked to explain this dependence, in terms of a large-scale magnetospheric asymmetry. In the current study, we present Cluster spacecraft observations from 12 October 2006 of earthward convective magnetotail plasma flows whose dusk-dawn sense disagrees with the untwisting hypothesis of IMF By control of the magnetotail flows. During this interval, observations of the upstream solar wind conditions from OMNI, and ionospheric convection data using SuperDARN, indicate a large-scale magnetospheric morphology consistent with positive IMF By penetration into the magnetotail. Inspection of the in-situ Cluster magnetic field data reveals a flapping of the magnetotail current sheet; a phenomenon known to influence dusk-dawn flow. Results from the curlometer analysis technique suggest that the dusk-dawn flow perturbations may have been driven by the J x B force associated with a dawnward-propagating flapping of the magnetotail current sheet, locally overriding the expected IMF By control of the flows. We conclude that invocation of the untwisting hypothesis may be inappropriate when interpreting intervals of dynamic magnetotail behaviour such as during current sheet flapping.

中文翻译:

与磁尾电流片拍动相关的可变黄昏-黎明流动力学

摘要。先前的观察已经清楚地表明,慢(< 200 km s -1)和快速(> 200 km s -1)对流磁尾流的黄昏-黎明(v ⊥y)感强烈地受行星际磁场控制(IMF)ÿ条件。磁尾动力学的相关“解旋假设”通常被用来解释这种依赖性,即大规模磁层不对称性。在目前的研究中,我们展示了集群航天器从 2006 年 10 月 12 日对地球对流磁尾等离子体流的观测,其黄昏-黎明意义与 IMF B y的解旋假设不一致。控制磁尾流。在此期间,来自 OMNI 的上游太阳风条件的观测以及使用 SuperDARN 的电离层对流数据表明,大规模磁层形态与正 IMF B y穿透到磁尾一致。原位集群磁场数据的检查揭示了磁尾电流片的摆动;一种已知会影响黄昏-黎明流动的现象。卷曲计分析技术的结果表明,黄昏-黎明流动扰动可能是由J  x  B力驱动的,该力与磁尾电流片的黎明向传播拍打相关,局部覆盖了预期的 IMF B y流量的控制。我们得出的结论是,在解释动态磁尾行为的间隔时,例如在电流片摆动期间,调用解捻假设可能是不合适的。
更新日期:2021-06-03
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