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摘要:
对2008—2010年覆盖中国空间的DEMETER卫星电场探测数据进行分析,共识别出328例磁层线辐射(MLR)事件。根据已有MLR事件的频谱特征,研究了中国空间的MLR事件的特征及其可能的原因。对所有MLR事件进行统计分析,结果表明这些事件白昼的出现率高于夜晚,秋冬季的出现率高于春夏季;与地磁活动水平无明显关联,主要出现在中国中低纬度地区空间;频率间隔主要分布在55~95 Hz,频率漂移速率大都在0~0.4 Hz/s,并且频谱最高强度与地理纬度无明确关联。中国空间MLR事件的特征与中国空间所观测到的电力线谐波辐射(PLHR)事件的特征相似,与国外已发现的MLR事件的特征有所不同。
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关键词:
- 磁层线辐射(MLR) /
- 电离层 /
- 卫星探测 /
- 空间环境 /
- 电力线谐波辐射(PLHR)
Abstract:The electric field data observed by DEMETER satellite in the space above China from 2008 to 2010 were analyzed, and 328 magnetospheric line radiation (MLR) events were detected. According to the spectrum of the existing MLR events, the characteristics and their possible cause of these MLR events were studied. We made statistical analysis on all MLR events, and the results indicated that there were more MLR events in daytime than in nighttime and more in winter and autumn than in summer and spring. MLR showed no significant dependence on geomagnetic activity. Most of events were distributed in the low and medium latitude. The frequency intervals of MLR events were between 55 Hz and 95 Hz, the frequency drift rates were mostly in the range of 0-0.4 Hz/s, and peak intensities in frequency-time spectrograms seemed to be independent of latitude. The characteristics of MLR events observed in the space above China were similar to those of power line harmonic radiation (PLHR) events, but different from those observed abroad.
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表 1 2008—2010年中国空间MLR事件按月份分布统计
Table 1. Monthly distribution of MLR events in space above China from 2008 to 2010
年份 1月 2月 3月 4月 5月 6月 7月 8月 9月 10月 11月 12月 总计 2008年 11 6 4 9 10 7 7 5 5 7 13 19 103 2009年 15 4 3 13 9 10 14 3 5 16 16 20 128 2010年 12 11 7 5 9 10 9 10 6 9 9 97 总计 38 21 14 27 28 27 30 18 16 32 38 39 328 表 2 2008春季至2009年冬季中国空间MLR事件按季节分布统计
Table 2. Seasonal distribution of MLR events in space above China from spring of 2008 to winter of 2009
季节 2008年 2009年 事件数 事件比例/% 事件数 事件比例/% 春 23 21.9 25 18.9 夏 19 18.1 27 20.5 秋 25 23.8 37 28.0 冬 38 36.2 43 32.6 总计 105 100 132 100 表 3 MLR事件频率间隔分布
Table 3. Distribution of MLR events' frequency spacing
频率间隔/Hz MLR事件数量 0~30 2 55~65 2 65~75 32 75~85 49 85~95 24 95~105 8 105~115 9 115~125 4 125~135 5 表 4 MLR事件的频率漂移速率分布
Table 4. Distribution of MLR events' frequency drift rate
频率漂移速率/(Hz·s-1) MLR事件数量 0~0.2 76 0.2~0.4 51 0.4~0.6 6 0.6~0.8 1 0.8~1.0 1 -
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