Periodicity of sunspot activity in the modern solar cycles
Periodicity of sunspot activity in the modern solar cycles
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DOI：
10.1360/03wd0154
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发表时间：
2004-11
期刊：
影响因子：
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通讯作者：
李可军;苏同卫;梁红飞
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文献类型：
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作者：
李可军;苏同卫;梁红飞
太阳黑子数、太阳黑子面积和太阳黑子单位面积通常用来表示太阳黑子的活动。本文利用小波变换分析了1874年5月至2004年5月期间太阳黑子活动三项指标的月均值，研究了现代太阳活动周的周期性。给出了它们的全局功率谱和局部功率谱，并对这些谱进行了统计检验。主要结果是：（1）太阳黑子数的局域小波功率谱与太阳黑子面积的局域小波功率谱相似，表明两者的周期性相似。太阳黑子单位面积的局部功率谱与前两个指数的局部功率谱相似，但看起来更为复杂。(2)太阳黑子活动的可能周期约为10.6年（或10.9年的太阳黑子单位面积），31和42年，约10.6年的周期在所考虑的时间是统计上显着的。在31年和42年左右的时间段内，其功率峰值在95%置信水平线以下，但在平均红噪声谱线以上，其余时间段的功率峰值甚至在平均红噪声谱线以下，这在统计上是不显著的。(3)三个时期的局部功率在所考虑的时间的后期比早期高。(4)三种指数的周期特征在整体功率谱和局部功率谱中表现出相似性，但在细节上存在差异。
Sunspot number, sunspot area and sunspot unit area are usually used to show sunspot activity. In this paper, periodicity of sunspot activity of modern solar cycles has been investigated through analyzing the monthly mean values of the three indices in the time interval of May 1874 to May 2004 by use of the wavelet transform. Their global power spectra and local power spectra are given while the statistical tests of these spectra are taken into account. The main results are (1) the local wavelet power spectrum of the sunspot number seems like that of the sunspot area, indicating that the periodicity of the both indices is similar. The local power spectrum of the sunspot unit area resembles the local power spectra of the previous two indices, but looks more complicated. (2) The possible periods in sunspot activity are about 10.6 (or 10.9 years for the sunspot unit area), 31 and 42 years, and the period of about 10.6 years is statistically significant in the considered time. For the periods of about 31 and 42 years, their power peaks are under the 95% confidence level line but over the mean red-noise, spectral line, and for the other rest periods, their power peaks are even under the mean red-noise spectral line, which are statistically insignificant. (3) The local power of the three periods is higher in the late stage than in the early stage of the considered time. (4) The period characteristics of the three indices, shown in the global power spectra and the local power spectra, are similar but there is difference in detail.