1700—2012年太阳黑子周期性变化的小波分析

Periodic Variations of Sunspot from 1700 to 2012 by Wavelet Analysis

为了研究太阳黑子的周期性变化规律,采用SIDC提供的1700—2012年逐年与1987—2012年逐日的太阳黑子数据,利用小波功率谱分别从长周期和短周期两个方面研究太阳黑子的周期,分析结果表明,太阳黑子存在3个显著性周期：0.075 a（27 d）、11.04 a和111.6 a,除此之外,还有55 a的局部显著周期。对太阳黑子数与太阳F10.7射电流量进行交叉小波变换,分析结果发现两者在10.1~12.3 a的尺度上有着显著的共振性。利用最小二乘谱分析方法得到太阳黑子时间序列各个周期的振幅和趋势信息,结果显示各个周期的振幅与其小波功率谱成正比关系,11.04 a的振幅最大,0.075 a最小,同时在1700—2012年间,太阳黑子呈现逐年递增的趋势,每年约增长0.08个单位。

To investigate the periodic change of sunspot, yearly sunspot data from 1700 to 2012 and daily sunspot data from 1987 to 2012 supplied by SIDC were used to analyze its periods by the wavelet power spectrum. The results show that the sunspot contains three significant periods, that is, 0. 075 a（ 27 d）, 11. 04 a, 111. 6 a. In addition, the period of 55 a is significant in the local time span. The results of cross wavelet transform between the sunspot number and the solar 10. 7 cm radio flux indicate that there is significant in-phase resonance oscillation between them in the scale from 10. 1 to 12. 3 a and the variation of sunspot and solar flux occur at the same time. Besides, the least square spectral analysis was used to fit the sunspot number time series and calculate periodic amplitudes and trend. The results represent that the amplitudes are direct ratio to corresponding wavelet power spectrum, the amplitude of 11. 04 a is maximum and the amplitude of 0. 075 a is minimum. The trend shows that the sunspot has been increasing from 1700 to 2012 and the increment is 0. 08 per year.