A case study of relationship between substorm expansion and global plasma convection
A case study of relationship between substorm expansion and global plasma convection
复制标题
亚暴扩展与全球等离子体对流关系的实例研究
DOI：
10.1029/2005gl024736
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发表时间：
2006
影响因子：
5.2
通讯作者：
J. Ruohoniemi
中科院分区：
文献类型：
--
作者：
K. Liou;J. Ruohoniemi
这封信报告了在两次大型且罕见的亚暴事件期间，SuperDARN雷达网络对大规模电离层等离子体流的观测以及极地紫外成像仪的全球极光图像。亚暴事件的特点是一个主要向西扩张，另一个主要向东扩张（或没有向西扩张）。向西扩张的情况与行星际磁场（IMF）的正y分量相关，而向东扩张的情况与IMF的负y分量相关。SuperDARN雷达网的同步等离子体流测量表明，向西（向东）的扩张嵌入在大而圆的黄昏（黎明）对流单体中。对观测到的向西扩张的优势提供了一个简单的解释，即午夜前的开始位置有利于与黄昏细胞相关的向西等离子体流。只有当一个大的IMF由负的条件下，导致午夜部门向东等离子体流占主导地位，才发生向东扩张。
This letter reports observations of large‐scale ionospheric plasma flows from the SuperDARN radar network and global auroral images from the Polar ultraviolet imager during two large and rare substorm events. The substorm events were characterized by predominantly westward expansion for one and predominantly eastward expansion (or lack of westward expansion) for the other. The westward expansion case was associated with a positive y‐component of interplanetary magnetic field (IMF), whereas the eastward expansion case was associated with a negative y‐component of IMF. The concurrent plasma flow measurements from the SuperDARN radar network suggest that the westward (eastward) expansion is embedded in the large, round dusk (dawn) convection cell. A simple explanation is offered for the observed preponderance of westward expansions, namely, that the pre‐midnight onset location favors the westward plasma flow that is associated with the dusk cell. Eastward expansion occurs only when a large IMF By negative condition causes the midnight sector to be dominated by eastward plasma flows.