New Data about Long-Term Changes of Solar Activity
The double Hale cycle (about 44 years) was found in changes of power-law index for integral distributions of equivalent diameters of large groups of sunspots having sizes of 50–90 Mm. According to the Greenwich catalog data, this cycle is traced in the last 13 cycles of solar activity, nos. 12–24. In addition to this periodic change, a unique sporadic phenomenon was discovered, namely, a sharp jump in the maximum diameters of sunspot groups in the 18th cycle (more precisely, in 1946–1947), which has no analogues in other cycles.
This study was funded by the Taras Shevchenko National University of Kyiv, project no. 16БФ023-01.
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