The equatorward boundary of auroral ion precipitation
The equatorward boundary of auroral ion precipitation
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极光离子降水赤道边界
DOI：
10.1029/ja092ia04p03273
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发表时间：
1987
影响因子：
--
通讯作者：
N. Heinemann
中科院分区：
文献类型：
--
作者：
M. Gussenhoven;D. Hardy;N. Heinemann
利用美国国防气象卫星计划（DMSP） F6卫星上SSJ/4探测器的数据，研究了极光离子和电子降水赤道边界位置的差异，以及极光离子和电子降水赤道边界位置的差异随磁地方时和磁活动的变化。SSJ/4探测器的离子传感器的大几何因子使得在大多数情况下离子边界的识别是明确的。在这项研究中，从1983年1月所有DMSP F6极光中分别确定了大约900个电子和离子的边界。这些边界发生在当地时间上午的0400到0700，晚上的1700到2100。用Kp测量，离子和电子边界都随着磁活度的增加系统地向低纬度移动。在采样的夜间扇形中，离子边界平均向电子边界赤道方向1.4°，差异通常可达3°。在清晨扇区，离子边界平均向电子边界偏2.6°，有相当多的情况差异在5.0°以上。电子和离子边界之间的分离不依赖于Kp，但在椭圆的早晨侧和晚上侧，从午夜到中午随着MLT的增加而增加。如果明确考虑到离子边界发展的时间，并且离子俯仰角扩散高度依赖于能量，则边界的分离可以用大尺度准静态对流电场中的运动来解释。
The data from the SSJ/4 detector on the Defense Meteorological Satellite Program (DMSP) F6 satellite are used to study the difference in the location of the equatorward boundaries of auroral ion and electron precipitation, and the variation in the difference with magnetic local time and activity. Large geometric factors of the ion sensors of the SSJ/4 detector make identification of the ion boundary unambiguous in most cases. In this study, approximately 900 boundaries each for electrons and ions were determined from all DMSP F6 auroral passes in January of 1983. The boundaries occur over local times from 0400 to 0700 on the morningside of the oval and from 1700 to 2100 on the eveningside. The ion and electron boundaries both move systematically to lower latitudes with increasing magnetic activity, as measured by Kp. Over the evening sector sampled, the ion boundary is on average 1.4° equatorward of the electron boundary, with the difference commonly ranging up to 3°. For the morning sector sampled, the ion boundary is on average 2.6° poleward of the electron boundary with a significant number of cases with differences above 5.0°. The separation between the electron and ion boundaries is not dependent on Kp but does increase with MLT from midnight toward noon on both the morningside and the eveningside of the oval. The separation in boundaries can be explained by motion in a large-scale, quasi-static convection electric field if the time for development of the ion boundary is explicitly taken into account and if ion pitch angle diffusion is highly energy dependent.