Relationship between Birkeland current regions, particle precipitation, and electric fields
Relationship between Birkeland current regions, particle precipitation, and electric fields
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伯克兰电流区域、颗粒降水和电场之间的关系
DOI：
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发表时间：
1993
期刊：
影响因子：
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通讯作者：
F. Rich
中科院分区：
文献类型：
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作者：
O. Beaujardiere;J. Watermann;P. Newell;F. Rich
研究了与Sondrestrom雷达观测一致的8个DMSP F7卫星通道的数据，以确定大尺度白天Birkland流与粒子降水区和对流模式的关系。采用了最近从DMSP颗粒数据中开发的分类方案。结果表明：(1)地幔电流(传统上称为尖点流)的当地时间并不局限于尖点本身的经度，而是覆盖了更大的当地时间范围。(2)地幔电流完全在开放场线上流动(这里的“开放场线”是指离子沉淀和电子沉淀具有等离子体地幔、尖峰或极雨特征的区域)。这证实并推广到所有当地时间从其他观测中获得的类似结果。(3)约有一半的1区电流流经开场线。这与区域1电流是由太阳风发电机产生并在分开开放和关闭场线的表面内流动的假设相一致。(4)80%以上的Birkland流边界不对应于粒子降水边界。区域2电流延伸到等离子体片向极地边界之外；区域1电流部分流经开放场线；地幔电流和地幔粒子不重合。(5)在大多数通道中，当观测到三重电流片(区域2、区域1和地幔电流)时，对流逆转位于闭合场线上。当只观测到两个电流片(区域2/区域1或区域1/地幔电流)时，对流逆转发生在开放场线上。(6)这些数据似乎更符合这样一种拓扑结构，即地幔电流是区域1电流的延伸，而不是位于区域1电流系统极地的单独系统。
Data from eight DMSP F7 satellite passes coincident with Sondrestrom radar observations have been examined to determine how the large-scale dayside Birkeland currents are related to the particle precipitation regions and to the convection pattern. The classification schemes recently developed from DMSP particle data were adopted. The observations were limited to the prenoon local time hours and led to the following conclusions: (1) The local time of the mantle currents (which were traditionally called cusp currents) is not limited to the longitude of the cusp proper, but covers a larger local time extent. (2) The mantle currents flow entirely on open field lines (where “open field lines” is defined as a region where the ion precipitation and electron precipitation have the characteristics of plasma mantle, cusp, or polar rain.) This confirms and extends to all local times similar results obtained from other observations. (3) About half of region 1 currents flow on open field lines. This is consistent with the assumption that the region 1 currents are generated by the solar wind dynamo and flow within the surface that separates open and closed field lines. (4) More than 80% of the Birkeland current boundaries do not correspond to particle precipitation boundaries. Region 2 currents extend beyond the plasma sheet poleward boundary; region 1 currents flow in part on open field lines; mantle currents and mantle particles are not coincident. (5) On most passes when a triple current sheet is observed (region 2, region 1, and mantle currents), the convection reversal is located on closed field lines. When only two current sheets are observed (either region 2/region 1, or region 1/mantle currents), the convection reversal is on open field lines. (6) The data appear to be more consistent with a topology such that mantle currents are an extension of region 1 currents, rather than a separate system located poleward of the region 1 current system.