The Upper Limit of Sunspot Activity as Observed over a Long Time Interval
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After analyzing the observational manifestations of the α- and ω-effects of the dynamo theory and using the modified Waldmeier rule, we show that the annual mean Wolf numbers at the maximum of the 11-year cycle that are likely to occur a time interval of 104 years have an upper limit amounting approximately to W EXTR∼230 – 240. Similar values were also obtained using the results by Usoskin et al. (2014, Astron. Astrophys. 562, L10), who considered the probability of various activity levels by reconstructing the variations of solar activity over three thousand years. As an additional result, the predicted maximum of Cycle 24 is refined and is shown to be W M=72 – 132 with a 95 % confidence.
KeywordsProbability Density Function Solar Activity Toroidal Field High Solar Activity Wolf Number
The work was partly supported by the Russian Foundation for Basic Research, grant number 13-02-00277, and by the Programs No. 9 and 41 of the Presidium of the Russian Academy of Sciences.