Traveling convection vortices induced by solar wind tangential discontinuities
Traveling convection vortices induced by solar wind tangential discontinuities
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太阳风切向不连续性引起的行进对流涡旋
DOI：
10.1029/2002ja009459
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发表时间：
2002
影响因子：
--
通讯作者：
J. Watermann
中科院分区：
文献类型：
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作者：
R. Kataoka;H. Fukunishi;L. Lanzerotti;T. Rosenberg;A. Weatherwax;M. Engebretson;J. Watermann
[1]研究了两个典型的伴有对流涡旋的磁脉冲事件。利用从北方和南半球高纬度地面磁力仪网络获得的磁场数据，对其共轭等效对流模式进行了分析。还利用从多颗国际日地物理卫星获得的太阳风数据对太阳风结构进行了三维分析。在1996年5月22日世界时13时10分观测到的第一次事件中，一个向西移动的TCV同时出现在北方和南半球的中午到黎明部门。太阳风源的TCV被发现是一个切向不连续（TD），这导致行星际磁场（IMF）的快速北转和突然的动态压力变化。在1998年5月27日世界时16时10分观测到的第二次事件中，一个向东移动的TCV出现在北方和南半球的正午扇区，在南半球的时间延迟为2至3分钟。再次发现TCV的太阳风源是TD，它导致了IMF的快速负转向和动压的突然增强。分析表明，驱动这些事件的TD的运动电场指向TD，其法向矢量与向日方向呈大锥角。这些TD满足在弓形激波处形成热流异常（HFA）的条件。扫过的TD和弓激波的交叉点的磁层的运动被发现是一致的，在每个事件中所观察到的TCV运动。HFA引起的磁层顶形变可以解释观测到的所有形态特征和这两个MIE的触发过程。然而，有人建议，突发合并和/或压力脉冲将加强由HFA产生的过程，因为TD通常伴随着IMF的突然变化和压力增强。因此，似乎可以合理地得出这样的结论：HFA、突发磁场合并和压力脉冲的综合过程产生了这些MIE和TCV的演化。索引术语：2784磁层物理学：太阳风/磁层相互作用; 2724磁层物理学：磁层顶、尖点和边界层; 2708磁层物理学：电流系统（2409）; 2463电离层：等离子体对流;关键词：移动对流涡旋、磁脉冲事件、行星际切向不连续性
[1] Two typical magnetic impulse events (MIEs) accompanied by traveling convection vortices (TCVs) are investigated. The analysis of their conjugate equivalent convection patterns is performed using magnetic field data obtained from high-latitude ground magnetometer networks in the Northern and Southern Hemispheres. A three-dimensional analysis of solar wind structures is also performed using solar wind data obtained from multiple International Solar-Terrestrial Physics satellites. In the first event observed at � 1310 UT on 22 May 1996, a westward moving TCV appeared simultaneously in the noon-to-dawn sector in the Northern and Southern Hemispheres. The solar wind source of this TCV is found to be a tangential discontinuity (TD), which causes a rapid northward turning of the interplanetary magnetic field (IMF) and abrupt dynamic pressure changes. In the second event observed at � 1610 UT on 27 May 1998, an eastward moving TCV appeared in the noon sector in the Northern and Southern Hemispheres, with a timing delay of 2 to 3 min in the Southern Hemisphere. The solar wind source of this TCV is found again to be a TD, which causes a rapid IMF By negative turning and an abrupt enhancement of dynamic pressure. Analyses show that the TDs driving these events have their motional electric fields pointing toward the TDs and their normal vectors with large cone angles from the sunward direction. These TDs satisfy the conditions for the formation of a hot flow anomaly (HFA) at the bow shock. The sweeping motion across the magnetosphere of the intersection of the TD and the bow shock is found to be consistent with the observed TCV motion in each event. Magnetopause deformations due to HFAs can explain all the observed morphological features and the triggering process of these two MIEs. It is suggested, however, that bursty merging and/or pressure pulses would reinforce the processes produced by the HFAs, since the TDs are usually accompanied by both abrupt IMF changes and pressure enhancements. Consequently, it seems reasonable to conclude that the integrated processes of HFA, bursty magnetic field merging, and pressure pulses produce the evolution of these MIEs and TCVs. INDEX TERMS: 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2724 Magnetospheric Physics: Magnetopause, cusp, and boundary layers; 2708 Magnetospheric Physics: Current systems (2409); 2463 Ionosphere: Plasma convection; KEYWORDS: traveling convection vortex, magnetic impulse event, interplanetary tangential discontinuity