采用北京宇宙线超中子堆 5min的数据,利用快速傅里叶变换计算宇宙线的功率谱方法,分析了 2001年11月24日特大磁暴前银河宇宙线短时间尺度(t<1h)的功率谱。计算结果表明,在 2001年11月18日到20日之间,银河宇宙线的功率谱没有特别突出的特征。在 2001年11月23日CME抛出之后到达磁层前的一段时间,银河宇宙线的22.6154min的周期非常显著,而其他短时间周期的特征变得很不明显,几乎变为噪声水平。

By analyzing the short time scale (t1 hour) power spectrum of cosmic rays observed at NM-64 Superneutron monitor at Beijing from Nov. 18/0000UT to 24/0000UT, 2001 before the severe magnetic storm with the lowest DST is-225. The analytical results show that there is no prominent period characteristic in cosmic rays power spectrum during the period form 18/0000UT to 20/0000UT. However, the 22.6154 minutes period characteristic of cosmic rays is very prominent during the period form 23/0000UT to 24/0000UT, while the other short time period characteristics are characterless which almost became noise level.