Ultra-High 11-Year Cycles Based on Radiocarbon Reconstruction of Solar Activity

The radiocarbon dating curve with a ten-year step has been known for more than half a century and is the main, most precise method of chronology of archaeological finds. Overlapping patterns of the ring thickness of preserved tree remains allow scientists to draw up a chronology for more than 10,000 years. A number of authors have already succeeded in reconstructing secular variations in solar activity for the Holocene. The precision of modern mass spectrometers allows researchers to work with smaller amounts of material, so that more and more chronological curves with an annual time step appear lasting up to 1000 years or more. Such curves, theoretically, should reflect the main, 11-year variations in solar activity. However, the amplitude of 11-year variations in the content of radiocarbon is comparable to the measurement error. The trajectory of a radiocarbon atom after it forms in the atmosphere until it enters a tree ring as a result of carbon exchange between natural reservoirs is very intricate and subject to various changing factors. In this paper, we discuss possible approaches to reconstructing 11-year solar activity cycles from radiocarbon and ways to improve their accuracy. In particular, we obtained a few high 11-year cycles (Wolf numbers up to 500) in the late 12th century, which cannot be revealed by applying excessive smoothing.