极隙区纬度Pc1-2波的统计分布特征

利用南极中山站和戴维斯站观测的感应式磁力计数据,运用互谱分析方法统计分析了2004年3、6、9、12月的Pc1-2波事件,研究了Pc1-2波出现频次、中心频率和振幅对季节和磁地方时的分布。结果共获得有效Pc1-2波事件2932件,其中,出现在3、9月较多,分别占51.4%和26.1%,12月次之,占18.6%,6月最少,占3.8%。两站的Pc1-2波事件有59.8%出现在磁中午(0800—1000 UT)附近,且在午后靠近磁中午的时候Pc1-2波的中心频率比在午前靠近磁中午的时候大,振幅则在0800 UT时出现最大值;此外,在6月,Pc1-2波的平均中心频率最大,而平均振幅则最小。这些结果表明,极隙区纬度Pc1-2波的传播在很大程度上受电离层电导率的影响。

STATISTICAL CHARACTERISTICS OF Pc1-2 WAVES NEAR THE CUSP LATITUDES

We recorded induction magnetometer data from Zhongshan and Davis Stations in Antarctica, for March, June, September, and December in 2004. We used cross-spectrum analysis to statistically study Pc1-2 wave occurrence, center frequency, and amplitude variations with respect to the seasons and magnetic local time. Of 2 932 valid wave events, Pc1-2 waves had a higher occurrence in March (51.4%) and September (26.1%) than in December (18.6%) and June (3.8%), and occurred most frequently near the magnetic local noon (59.8% at 0800–1000 UT). The wave center frequency was higher post-noon than pre-noon and the wave amplitude reached a maximum at 0800 UT. The maximal center frequency and minimal amplitude occurred in June. These results suggest that Pc1-2 wave properties near the cusp latitudes are strongly influenced by ionospheric conductivity.