English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We investigated the Korean records of naked-eye sunspot observations andfound an implication of periodicity of about 200-year. Adding the Chineserecords we showed that the historical naked-eye sunspot observations have thesimilar periodicity. Recent some works showed that there would be no intrinsicperiodicities except 11-year cycle. We adopt the new approach called samplogramto test sampling stability of cycles in terms of power spectra and differenceseries and show that the Suess/de Vries cycle of about 207-year is adeterministic cycle of the stochastic solar activity. Also we show thatoccurrences of grand minimum are not necessarily expected with the Suess/deVries cycle and it is possible to appear double or multiple grand maximawithout a grand minimum within them.

About 200-Year Cycle of Solar Activity in the Mediaeval Korean Records and Reconstructions from Cosmogenic Radionuclides