Modulation of nightside polar patches by substorm activity
Modulation of nightside polar patches by substorm activity
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DOI：
10.5194/angeo-27-3923-2009
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发表时间：
2009-10
影响因子：
1.9
通讯作者：
A. Wood;S. E. Pryse;J. Moen
中科院分区：
文献类型：
--
作者：
A. Wood;S. E. Pryse;J. Moen
抽象的。本文介绍了一项多仪器研究的结果，显示了地磁亚暴活动对高纬度电离层等离子体空间分布的影响。2001年12月12日的非相干散射雷达和无线电层析成像测量被用来直接观测夜侧电离层极斑的残余物并调查其特征。斑块发生在IMF Bz负和IMF By负的条件下。他们被归因于白天光电离输送的高纬度对流模式在极冠和夜间欧洲部门。在亚风暴扩张期间，夜面的斑块之间相隔约5°的纬度，但当活动消退后，这一距离缩小到约2°。不同的斑块分离是由于高纬等离子体对流型在夜面响应亚暴活动而扩张和收缩的结果。较大分离的斑块发生在反向阳的交叉极流进入夜侧扇区时。那些较小的分离也在反向阳流，但接近赤道边缘的对流模式，在较慢的，发散的流动在哈朗不连续。补丁的重复时间约为10至30分钟，估计取决于亚暴的阶段。
Abstract. Results are presented from a multi-instrument study showing the influence of geomagnetic substorm activity on the spatial distribution of the high-latitude ionospheric plasma. Incoherent scatter radar and radio tomography measurements on 12 December 2001 were used to directly observe the remnants of polar patches in the nightside ionosphere and to investigate their characteristics. The patches occurred under conditions of IMF Bz negative and IMF By negative. They were attributed to dayside photoionisation transported by the high-latitude convection pattern across the polar cap and into the nighttime European sector. The patches on the nightside were separated by some 5° latitude during substorm expansion, but this was reduced to some 2° when the activity had subsided. The different patch separations resulted from the expansion and contraction of the high-latitude plasma convection pattern on the nightside in response to the substorm activity. The patches of larger separation occurred in the antisunward cross-polar flow as it entered the nightside sector. Those of smaller separation were also in antisunward flow, but close to the equatorward edge of the convection pattern, in the slower, diverging flow at the Harang discontinuity. A patch repetition time of some 10 to 30 min was estimated depending on the phase of the substorm.