佘山地磁台百年磁暴(一)——太阳周期变化

Sheshan hundred years data of geomagnetic storms I:solar cycle variations

上海佘山地磁台位于中纬度地区,拥有逾百年的连续地磁场观测资料,非常有利于研究地磁活动的周期规律.本文利用该台站1908至2007年的100年磁暴记录,通过时序叠加、傅里叶分析和小波分析研究了磁暴的周期规律.结果表明:强磁暴具有显著的11年、22年和季节变化;弱中等磁暴没有明显的11年周期,并且季节变化的幅度较小.奇/偶太阳活动周相比,强磁暴的季节变化存在一定的差异,低年季节变化不明显,高年季节变化显著,并且偶数周的变化相对复杂.

The mid-latitude geomagnetometer of Sheshan holds a successive geomagnetic field data set even more than one-hundred years, which is benefit for the period research of the geomagnetic activity. By the methods of Time Series Superposition, Fourier Analysis and Wavelet Analysis, geomagnetic storms during one hundred years in the intervals between 1908 to 2007 of the observatory are analyzed for the period laws of the geomagnetic storm. The results have shown that, a prominent 11-year cycle, 22-year cycle and semiannual variation are clearly seen in the strong geomagnetic storms, but unconspicuous 11-year cycle and little semiannual variation are also known in the moderate and weak storms. Furthermore, the semiannual variation of the strong storm shows differences between the odd and the even solar cycle, with a remarkable semiannual variation in high solar activity years and complicated variations in the even solar cycle years.