Dayside magnetospheric and ionospheric responses to solar wind pressure increase: Multispacecraft and ground observations
Dayside magnetospheric and ionospheric responses to solar wind pressure increase: Multispacecraft and ground observations
复制标题
日侧磁层和电离层对太阳风压力增加的响应：多航天器和地面观测
DOI：
10.1002/2016ja022459
复制
发表时间：
2016
影响因子：
2.8
通讯作者：
Fu S Y
中科院分区：
文献类型：
--
作者：
Tian A M;Shen X C;Shi Q Q;Tang B B;Nowada M;Zong Q G;Fu S Y
我们提供了2008年9月30日初冲（PI）和主冲（MI）事件期间日侧磁层瞬变现象的现场观测。PI和MI地磁信号是由等效电离层电流中极性相反的双行对流涡旋引起的，这是由于太阳风动压的突然增加。两个与PI‐相关的电离层涡旋分别集中在~07磁地方时（MLT）、67°磁纬度（MLAT）和~14磁地方时（MLAT）、73°磁纬度（MLAT）。黎明侧MI流中心位于~68°MLAT和~6 MLT，而黄昏侧MI流中心在~67°MLAT和~75°MLAT之间以~5.6 ~ 7.4 km/s的速度向极地移动。研究发现，在4 MLT范围内，都能看到黎明侧PI -和MI -相关的涡旋。在日侧外磁层中，利用“亚暴期间事件时间历史与宏观尺度相互作用”（THEMIS）卫星观测到一个径向尺度大于3re的顺时针涡旋流，并伴有正场对准电流（FAC）。流动涡旋在磁层中扩展并向尾部移动，也被全球MHD模拟再现。基于观测和模拟技术，我们发现与MI相关的FACs与大尺度流动涡相关。PI - FACs部分是由近赤道平面的快模波向alfvsamn波的模式转换提供的，而大部分可能在磁层的高纬度区域产生。
We provide in situ observations of the transient phenomena in the dayside magnetosphere during the preliminary impulse (PI) and main impulse (MI) event on 30 September 2008. The PI and MI geomagnetic signals are induced by twin traveling convection vortices with opposite polarities in the equivalent ionospheric currents due to a sudden increase of the solar wind dynamic pressure. The two PI‐associated ionospheric current vortices centered at ~07 magnetic local time (MLT), 67° magnetic latitude (MLAT) in the dawnside and ~14 MLT, 73°MLAT in the duskside, respectively. The dawnside MI current vortex centered at ~68° MLAT and 6 MLT, while the duskside vortex center was traveling poleward from ~67° MLAT to ~75° MLAT at a speed of ~5.6–7.4 km/s around 14 MLT. It is found that both dawnside PI‐ and MI‐related current vortices were azimuthally seen up to 4 MLT. Following the magnetosphere sudden impulse, a clockwise flow vortex with a radial scale larger than 3 RE, associated with positive field‐aligned current (FAC), was observed by Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft in the outer dayside magnetosphere. The flow vortex expanded and traveled tailward in the magnetosphere, also being reproduced with global MHD simulations. Based on both observation and simulation technique, we show that the MI‐related FACs are correlated with the large‐scale flow vortex. The PI FACs are partially provided by the mode conversion of fast mode waves into the Alfvén waves near the equatorial plane, while most of it may be generated at a higher‐latitude region in the magnetosphere.