Nakamura Rumi, Nagai Tsugunobu, Birn Joachim, Sergeev Victor A, Le Contel Olivier, Varsani Ali, Baumjohann Wolfgang, Nakamura Takuma, Apatenkov Sergey, Artemyev Anton, Ergun Robert E, Fuselier Stephen A, Gershman Daniel J, Giles Barbara J, Khotyaintsev Yuri V, Lindqvist Per-Arne, Magnes Werner, Mauk Barry, Russell Christopher T, Singer Howard J, Stawarz Julia, Strangeway Robert J, Anderson Brian, Bromund Ken R, Fischer David, Kepko Laurence, Le Guan, Plaschke Ferdinand, Slavin James A, Cohen Ian, Jaynes Allison, Turner Drew L
1Space Research Institute, Austrian Academy of Sciences, Graz, Austria.
2Tokyo Institute of Technology, Tokyo, Japan.
Earth Planets Space. 2017;69(1):129. doi: 10.1186/s40623-017-0707-2. Epub 2017 Sep 18.
We report on the large-scale evolution of dipolarization in the near-Earth plasma sheet during an intense (AL ~ -1000 nT) substorm on August 10, 2016, when multiple spacecraft at radial distances between 4 and 15 were present in the night-side magnetosphere. This global dipolarization consisted of multiple short-timescale (a couple of minutes) disturbances detected by spacecraft distributed over 9 MLT, consistent with the large-scale substorm current wedge observed by ground-based magnetometers. The four spacecraft of the Magnetospheric Multiscale were located in the southern hemisphere plasma sheet and observed fast flow disturbances associated with this dipolarization. The high-time-resolution measurements from MMS enable us to detect the rapid motion of the field structures and flow disturbances separately. A distinct pattern of the flow and field disturbance near the plasma boundaries was found. We suggest that a vortex motion created around the localized flows resulted in another field-aligned current system at the off-equatorial side of the BBF-associated R1/R2 systems, as was predicted by the MHD simulation of a localized reconnection jet. The observations by GOES and Geotail, which were located in the opposite hemisphere and local time, support this view. We demonstrate that the processes of both Earthward flow braking and of accumulated magnetic flux evolving tailward also control the dynamics in the boundary region of the near-Earth plasma sheet.Graphical AbstractMultispacecraft observations of dipolarization (). Magnetic field component normal to the current sheet (BZ) observed in the night side magnetosphere are plotted from post-midnight to premidnight region: GOES 13, Van Allen Probe-A, GOES 14, GOES 15, MMS3, Geotail, Cluster 1, together with a combined product of energy spectra of electrons from MMS1 and MMS3 and auroral electrojet indices. Spacecraft location in the GSM X-Y plane (). Colorcoded By disturbances around the reconnection jets from the MHD simulation of the reconnection by Birn and Hesse (1996) (). MMS and GOES 14-15 observed disturbances similar to those at the location indicated by arrows.
我们报告了2016年8月10日一次强烈（AL约为 -1000 nT）亚暴期间近地等离子体片中双极化的大规模演化情况，当时在夜侧磁层中存在多个位于4至15个地球半径距离之间的航天器。这种全球双极化由分布在9个磁地方时（MLT）的航天器检测到的多个短时间尺度（几分钟）的扰动组成，这与地面磁力仪观测到的大规模亚暴电流楔一致。磁层多尺度任务（Magnetospheric Multiscale）的四个航天器位于南半球等离子体片中，并观测到了与这种双极化相关的快速流动扰动。磁层多尺度任务航天器的高时间分辨率测量使我们能够分别检测场结构和流动扰动的快速运动。在等离子体边界附近发现了流动和场扰动的独特模式。我们认为，在局部流动周围产生的涡旋运动在与束流型流（BBF）相关的R1/R2系统的赤道外一侧导致了另一个场向电流系统，正如局部重联喷流的磁流体动力学（MHD）模拟所预测的那样。位于相反半球和地方时的地球同步环境卫星（GOES）和“地球尾”（Geotail）的观测结果支持了这一观点。我们证明，向地球方向流动的制动过程和积累的磁通量向尾部演化的过程也控制着近地等离子体片边界区域的动力学。
图形摘要
双极化的多航天器观测（）。从午夜后到午夜前区域绘制了夜侧磁层中观测到的垂直于电流片的磁场分量（BZ）：地球同步环境卫星13号、范艾伦探测器A、地球同步环境卫星14号、地球同步环境卫星15号、磁层多尺度任务3号航天器、“地球尾”、星簇1号，以及磁层多尺度任务1号和3号航天器电子能谱的组合产物和极光电集流指数。航天器在地理坐标系（GSM）X - Y平面中的位置（）。由比尔恩和黑塞（1996年）重联的磁流体动力学模拟中重联喷流周围的扰动进行颜色编码（）。磁层多尺度任务航天器和地球同步环境卫星14 - 15号观测到的扰动与箭头所示位置的扰动相似。
