Long-Term Solar Cycle Evolution: Review of Recent Developments

Abstract

Abstract. The sunspot number series forms the longest directly observed index of solar activity and allows to trace its variations on the time scale of about 400 years since 1610. This time interval covers a wide range from seemingly vanishing sunspots during the Maunder minimum in 1645 -1700 to the very high activity during the last 50 years. Although the sunspot number series has been studied for more than a century, new interesting features have been found even recently. This paper gives a review of the recent achievements and findings in long-term evolution of solar activity cycles such as determinism and chaos in sunspot cyclicity, cycles during the Maunder minimum, a general behaviour of sunspot activity during a great minimum, the phase catastrophe and the lost cycle in the beginning of the Dalton minimum in 1790s and persistent 22-year cyclicity in sunspot activity. These findings shed new light on the underlying physical processes responsible for sunspot activity and allow a better understanding of such empirical rules as the Gnevyshev-Ohl rule and the Waldmeier relations.

A Remarkable Recent Transition in the Solar Dynamo

“…A very well-known Grand Episode is the Maunder Minimum that lasted from about 1610 till about 1740. Another episode, one of the highest of the past ten thousand years (Usoskin and Mursula 2003;Solanki et al 2004) is the recent 20th Century (Grand) Maximum, this being the period of large solar activity during the main part of the 20th century. It was characterized by strong Schwabe cycles with their associated phenomena such as an abundant number of solar flares and also by related features such as the increased interplanetary magnetic flux (Solanki et al 2000).…”

Properties of sunspot cycles and hemispheric wings since the 19th century

“…The beginning of a new cycle wing and the end of an old cycle wing usually overlap in time by a few years around the cycle minimum, leading to a superposition of the two wings (and cycles) around the minimum. Analysing separate wings makes it possible to study the so-called extended cycles (Wilson et al 1988;Usoskin & Mursula 2003;Cliver 2014), the latitudinal evolution of sunspots, the hemispheric differences and other surface phenomena produced by the solar dynamo. We study the sunspot groups and determine, for instance, the length and overall group activity of each wing separately.…”

Variability of rainfall and temperature (1912–2008) parameters measured from Santa Maria (29°41′S, 53°48′W) and their connections with ENSO and solar activity

“…Sunspot number is the longest directly measured solar activity index available and is representative of the general state of solar activity (Hoyt and Schatten, 1997). Analysis of sunspot number time series allowed the identification of the two main characteristic periodic variations of the solar activity: the 11-year sunspot cycle (Schwabe cycle) and the 22-year solar magnetic cycle (Hale cycle) (Lang, 2001;Usoskin and Mursula, 2003). While the Schwabe cycle is mainly related to the irradiance variations (Fröhlich, 2011) the Hale cycle is mainly related to the modulation of galactic cosmic rays (Singh et al, 2011).…”