Cycles in solar activity, especially of long periods, and certain terrestrial relationships

A periodicity of 92 years, found by G. Sirén in tree growth at the three-limit in northern Scandinavia for the time 1181–1960 A.D., is found to be satisfactorily coordinated with the maxima and minima of the cycle usually called the 80-yr cycle, but which according to our opinion is a 4 × 22.2-yr cycle. A periodicity of similar length according to G. Sirén and P. Hari also is exhibited in glacial summer clay sediments from Estonia (12, 000 B.P.) This, however, is too far back in time to allow a comparison with the simultaneous solar activity. A 260-yr periodicity in the stratigraphy found in raised bogs in Denmark by A. Aabye could be compared with variations in the tree growth and the solar activity for about the last 1,000 years. This is of the same length as a periodicity that was found in 1920 by H.H. Turner in pre-telescopic, Chinese observations of sunspots, as well as in the rise of the Nile, and in annular rings of Californian trees. We propose a cycle of 12 × 22.2 yr. Twice that period was claimed by Aabye for changes of the shore-line in Blekinge, Southern Sweden, too far back in time however to be connected to known solar changes. While the approximately 11-yr period of solar activity (sunspots) is well documented, as is also the 2× 11-yr period with regard to the magnetic polarity of the spots, the longer periods have not been investigated as much. This is largely due to the fact that the shorted a period is, the more complete periods underly a study, but part of the reason is also that long periods may not be as distinct as the two basic periods in amplitude and period length. The effects of long periods on terrestrial phenomena can, however, be very evident and greater than the effect of the shorter periods.