Long-term solar activity explored with wavelet methods

Abstract

Abstract. Long-term solar activity has been studied with a set of wavelet methods. The following indicators of longterm solar activity were used; the group sunspot number, the sunspot number, and the 14 C production rate. Scalograms showed the very long-term scales of 2300 years (Hallstat cycle), 900-1000 years, 400-500 years, and 200 years (de Vries cycle). Scalograms of a newly-constructed 14 C production rate showed interesting solar modulation during the Maunder minimum. Multi-Resolution Analysis (MRA) revealed the modulation in detail, as well as peaks of solar activity not seen in the sunspot number. In both the group sunspot number scalogram and the 14 C production rate scalogram, a process appeared, starting or ending in late 1700. This process has not been discussed before. Its solar origin is unclear.The group sunspot number ampligram and the sunspot number ampligram showed the Maunder and the Dalton minima, and the period of high solar activity, which already started about 1900 and then decreased again after mid 1990. The decrease starts earlier for weaker components. Also, weak semiperiodic activity was found.Time Scale Spectra (TSS) showed both deterministic and stochastic processes behind the variability of the long-term solar activity. TSS of the 14 C production rate, group sunspot number and Mt. Wilson sunspot index and plage index were compared in an attempt to interpret the features and processes behind the long-term variability.

A reconstruction of radiocarbon production and total solar irradiance from the Holocene <sup>14</sup>C and CO<sub>2</sub> records: implications of data and model uncertainties

“…Well-known solar periodicities in TSI contain the Hallstatt (2300 yr), Eddy (1000 yr), Suess (210 yr) and Gleissberg cycle (70-100 yr) as also discussed by Wanner et al (2008) and Lundstedt et al (2006). These periodicities are also present in our reconstruction (Fig.…”

Sunspot Count Periodicities in Different Zurich Sunspot Group Classes Since 1986

“…This method has been extensively applied in solar physics e.g. Torrence and Compo, 1998;Krivova and Solanki, 2002;Lundstedt et al, 2006;Li et al, 2011;Deng et al, 2013;Choudhary et al, 2014 and references therein). Contrary to the classical Fourier analysis that decomposes a signal into different sine and cosine functions which are not bounded in time, the wavelet transform uses wavelets characterized by scale (frequency) and time localization.…”

不久的将来气候会变冷吗？

“…Vries 周期和 2300 a Hallstatt 周期, 现在就有可能开 始 一 个 新 的 极 小 期 . 但 是 现 在 还 不 敢 做 这 样 的 预 报 [26] . 然而, 如前所述, 目前太阳活动各种指数已经 或即将接近 20 世纪初 1910~1920 年的水平, 也就是 Gm 的后期, 因此未来出现一个太阳活动极小期的可 能性是存在的, 当然如果出现一个极小期, 其强度及 长度, 也还很难预测.…”