SCALING THE 14C-EXCURSION SIGNAL IN MULTIPLE TREE-RING SERIES WITH DYNAMIC TIME WARPING.

A signal of rapid changes in ¹⁴C production is logged in annual series of ¹⁴C derived from tree rings, which can be associated with diverse effects of cosmic-ray fluxes, including solar burst and supernova events. These ¹⁴C signatures may vary in time and space. The intensity and structure of the ¹⁴C signal is multifaced, which complicates understanding of the forcing and attribution of the underlying astrophysical events. It was suggested that Δ¹⁴C in 1052/53 CE and 1054/55 CE signatures at a 4‰–6‰ range over two years could be caused by the Crab Nebula supernova (SN1054) or/and solar perturbation. The temporal incoherence of the signals in published ¹⁴C series is investigated with dynamic time warping (DTW), novel approach for matching time-behavioral patterns in multiple ¹⁴C datasets. DTW analysis of four ¹⁴C signatures from tree rings of California, Finland and England suggests that ¹⁴C spikes between 1052 CE and 1055 CE can be caused by a single event. The flickering fingerprint may result from cross-dating inconformity. Cross-checking of tree-ring records from distant locations is impossible sometimes due to large difference in environmental conditions limiting tree growth. The methodology helps to align the signals and can be applied to other ¹⁴C datasets. [ABSTRACT FROM AUTHOR]