探测一号卫星在近地磁尾观测到的尾向流统计特性

在磁静和亚暴期间,TC 1卫星在近地磁尾，包括晨昏两侧和夜侧的尾瓣、等离子体片边界层和等离子体片区域都观测到大量来自电离层的尾向流事件.尾向流在赤道面附近最强，在夜侧较晨昏两侧强；尾向流有从晨昏两侧向夜侧运动的趋势；尾向流随距地球距离增加而逐渐增强.与来自中磁尾的地向流相比，近地磁尾近赤道区域来自电离层的尾向流具有低温高密特性.2004年7月1日至2004年10月31日期间TC 1卫星在近地磁尾（7RE～13RE之间，RE为地球半径）观测到持续时间超过3 min的尾向流共516起.对这516起尾向流的统计研究结果显示：（1）尾向流在从等离子体片边界层向等离子体片的运动过程中流速会逐渐减弱、密度逐渐增高，温度有逐渐下降的趋势；（2）对尾向流平行温度和垂直温度的分析显示不同等离子体区域的尾向流都有较明显的各向异性；（3）在从等离子体片边界层向等离子体片的运动过程中，尾向流逐渐趋向各向同性.

The statistical characteristics of the tailward flows in the near-Earth region explored by TC-1

During quiet time and substorm process, tailward flow often explored in the near-Earth magnetotail by TC-1 satellite. The tailward flow is most strong near the equator, and stronger in the dusk-side and dawn-side than that in the night-side. The tailward flow tends to move from the dusk-side and dawn-side to the night-side, and becomes stronger while moving away the Earth. From 1, Jul. 2004 to 31, Nov. 2004, TC-1 satellite explored 516 tailward flow events between 7R_E to 13R_E, which the duration exceed 3 min. The statistic results showed that: Compared with the earward flow from the mid-tail, the near-Earth low latitude tailward flow from the ionosphere is characteristic of the low-temperature and high density; With the tailward flow moving from the lobal region to the plasma sheet, the velocity of the tailward flow decrease, the density and the temperature increase. The tailward flow has distinct anisotropy depending on the difference of the parallel with perpendicular temperature.