A study of short-period variation in solar activity

• Published in: Research in astronomy and astrophysics 2014-08, Vol.14 (8), p.1011-1018
• Main Authors: Chen, Ji-Long, Zhao, Juan
• Format: Article
• Language: English
• Subjects: Amplitudes; Astronomy; Correlation; Fluctuation; Low frequencies; Solar activity; Spectra; Sunspots; 三次函数; 二次函数; 低频波动; 太阳活动; 太阳黑子数; 正相关关系; 短周期变化; 长期变化
• ISSN: 1674-4527; 2397-6209
• DOI: 10.1088/1674-4527/14/8/011

We introduce two methods to detect short-period variation in solar activity. These are called amplitude of low frequency fluctuation （ALFF） and fractional am- plitude of low frequency fluctuation （FALFF）. We find a positive correlation between short-period variation and 11-year variation of solar activity using these two methods. Through ALFF, we find that solar activity over a short period becomes intensive when the 11-year solar activity is intensive. The ALFF value of the short period activity varies with the peak in sunspot number as a quadratic function. Through FALFF we find that the ratio of short-period spectral intensity to intensity over the whole period of solar activity will increase when the 11-year period of solar activity is intensive. The short-period FALFF value varies with the peak in sunspot number according to a cubic function. Using ALFF, we obtain a yearly series of solar activity that varies over a short period of 1-5 yr from 1860 to 2003, which shows an obvious periodicity of about 22 yr, 33 yr, 11 yr and a century. These short period variations show good correlations with long term variations in solar activity.