Solar activity cycle of ∼200 yr from mediaeval Korean records and reconstructions of cosmogenic radionuclides

Abstract

ABSTRACT We have investigated Korean records of naked-eye observations of sunspots and we have found evidence that implies a periodicity of about 200 yr. Adding Chinese records, we show that these historical naked-eye observations of sunspots have a similar periodicity. Recently, some authors have shown that there are no intrinsic periodicities except for the 11-yr cycle. We adopt a new approach called a samplogram to test the sampling stability of cycles in terms of power spectra and difference series. We show that the Suess/de Vries cycle of about 207 yr is a deterministic cycle of stochastic solar activity. Also, we show that occurrences of grand minima are not necessarily expected with the Suess/de Vries cycle and it is possible for double or multiple grand maxima to appear without a grand minimum within them.