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2 Bulletin of the Polish Academy of Sciences. Earth Sciences

2 2003

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Schwabe Solar Cycle in Tree-Ring Sequences from the Last 4000 Years (Southern Poland)

Krawczyk A., Krąpiec M.

Bulletin of the Polish Academy of Sciences. Earth Sciences

2003

Vol. 51, nr 2

91-98

This paper presents results of investigations on possibilities of finding periodicity related to solar activity changes in annual growth sequences of trees. The research materials were six chronologies based on subfossil oak trunks (so-called black oaks) coming from alluvial deposits of the Vistula river in the vicinities of Cracow. The analyzed chronologies cover the period of the last 4000 years. Treatment of these data with the methods of spectral analysis of time series permitted to conclude that they all contained distinct cyclic components, of which periods could correspond to the periods of cyclic changes of solar activity. The results obtained confirm the earlier presented thesis that in the analyzed period of time the length of the basic, so-called 11-year (Schwabe) solar cycle declined to below 10 years.

Annual Growth Sequences and Solar Activity Cycles (Examples from Subfossil Oaks from Southern Poland)

Krawczyk A., Krąpiec M.

Bulletin of the Polish Academy of Sciences. Earth Sciences

2003

Vol. 51, nr 1

29-41

This work presents results of studies on possibilities of finding periodicity related to solar activity changes in annual growth sequences of trees. The analyzed material were subfossil oak trunks (so-called black oaks) lifted from alluvial deposits of the Vistula river in the vicinity of Cracow, which had been felled and subsequently buried around 8000, 4600, 3500, 2000 and 1000 years ago. Treatment of the tree-ring data with methods of spectral analysis of time series revealed that most of the analyzed annual growth sequences contained distinct cyclic components, among them such ones of which periods might have corresponded to periods of solar activity cyclic changes. The obtained results suggest that lengths of the identified cycles were increasing between 8000 and 4600 years ago and decreasing in later millennia.