3D GUMICS Simulations of Northward IMF Magnetotail Structure
3D GUMICS Simulations of Northward IMF Magnetotail Structure
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DOI：
10.1029/2023ja031317
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发表时间：
2023-07
期刊：
影响因子：
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通讯作者：
L. J. Fryer;R. Fear;I. Gingell;J. Coxon;M. Palmroth;S. Hoilijoki;P. Janhunen;A. Kullen;P. Cassak
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文献类型：
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作者：
L. J. Fryer;R. Fear;I. Gingell;J. Coxon;M. Palmroth;S. Hoilijoki;P. Janhunen;A. Kullen;P. Cassak
本研究使用全球MHD模型大统一磁层-电离层耦合模拟第4版（GUMICS-4）重新评估了Kullen和Janhunen（2004，https：//doi.org/10.5194/angeo-22-951-2004）的全球北向行星际磁场（IMF）模拟。我们研究了向北IMF条件和地球磁尾之间的动态耦合，并将结果与基于观测的跨极弧形成机制进行了比较。这项研究的结果表明，在向北IMF条件（和向北IMF初始化），一个大的封闭的磁力线区域形成的磁尾，与从航天器数据观察到的跨极弧结构的相似之处。这一解释得到了磁尾闭合磁通量同时增加的支持。然而，重联配置不同，在几个方面，从以前的理论磁尾结构，已推断出从观测和模拟结果，并与transpolar弧。我们观察到黎明-黄昏波瓣区域是由于初始化阶段的高纬度重联而形成的，后来随着IMF By分量的变化导致磁尾扭曲而接触。我们的结论是，在GUMICS模拟中，跨极弧状结构是由于磁尾重联而形成的，而不是高纬度重联，或者是由于等离子体片通过扭曲的磁尾的映射，正如先前对GUMICS模拟的分析所解释的那样。
This study presents a re‐evaluation of the Kullen and Janhunen (2004, https://doi.org/10.5194/angeo-22-951-2004) global northward interplanetary magnetic field (IMF) simulation, using the Grand Unified Magnetosphere–Ionosphere Coupling Simulation version 4 (GUMICS‐4), a global MHD model. We investigate the dynamic coupling between northward IMF conditions and the Earth’s magnetotail and compare the results to observation‐based mechanisms for the formation of transpolar arcs. The results of this study reveal that under northward IMF conditions (and northward IMF initialization), a large closed field line region forms in the magnetotail, with similarities to transpolar arc structures observed from spacecraft data. This interpretation is supported by the simultaneous increase of closed flux measured in the magnetotail. However, the reconnection configuration differs in several respects from previously theorized magnetotail structures that have been inferred from both observations and simulations results and associated with transpolar arcs. We observe that dawn–dusk lobe regions form as a result of high‐latitude reconnection during the initialization stages, which later come into contact as the change in the IMF By component causes the magnetotail to twist. We conclude that in the GUMICS simulation, transpolar arc‐like structures are formed as a result of reconnection in the magnetotail, rather than high‐latitude reconnection or due to the mapping of the plasma sheet through a twisted magnetotail as interpreted from previous analysis of GUMICS simulations.