A Cyclogram Analysis of the Bratislava 14C Tree-Ring Record During the Last Century

Abstract

Radiocarbon variations in dated tree-ring samples represent an important tool for the study of the history of solar activity and sun-earth relationships. From this point of view, an investigation of the 11-year radiocarbon cycle is very important. Our cyclogram analysis of the Δ 14C record in tree-ring samples during the last century has confirmed previous results obtained by conventional harmonic analysis, eg, the average amplitude of 2, the phase shift of 3–5 yr for different 11-yr solar cycles, and the anticorrelation dependence of Δ 14C on Wolf sunspot numbers. The observed shorter periodicity (ca 9 yr for Δ 14C compared to 10.5 yr for sunspots), may be due to extra factors in sun-earth relationships.