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Reconstruction of the solar activity to 11,000 years BP and possible long-term periodicities
Střeštík, Jaroslav
Observations of solar activity (Wolf sunspot numbers) last only about 250 years, moreover, from sporadic observations the solar activity can be estimated approximately to the year 1500. In addition to the well-known eleven-year period some long-term periods seem to take place. This means that the values at the maxima of 11-yr solar cycles in certain periods are higher than those in other ones. Based on the analysis of dust fallout containing radioactive elements, conserved in glaciers, some authors reconstructed the solar activity first one millennium back, and later more millennia back. The longest series begins 9000 years B. C. and these data are published. Strangely, most authors of these the reconstructions do not look for possible periodicities, or only marginally. Here the possible periodicities obtained from a series of 11,000 years long have been presented. The results suggest a superlong periodicity with the length about 6500 years, on the other hand, they do not confirm variations with the length between 100 and 200 years, which are not persistent.
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