Solar superstorm of AD 774 recorded subannually by Arctic tree rings

J. Uusitalo, L. Arppe, T. Hackman, S. Helama, G. Kovaltsov, K. Mielikäinen, H. Mäkinen, P. Nöjd, V. Palonen, I. Usoskin, M. Oinonen

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Recently, a rapid increase in radiocarbon (14C) was observed in Japanese tree rings at AD 774/775. Various explanations for the anomaly have been offered, such as a supernova, a γ-ray burst, a cometary impact, or an exceptionally large Solar Particle Event (SPE). However, evidence of the origin and exact timing of the event remains incomplete. In particular, a key issue of latitudinal dependence of the 14C intensity has not been addressed yet. Here, we show that the event was most likely caused by the Sun and occurred during the spring of AD 774. Particularly, the event intensities from various locations show a strong correlation with the latitude, demonstrating a particle-induced 14C poleward increase, in accord with the solar origin of the event. Furthermore, both annual 14C data and carbon cycle modelling, and separate earlywood and latewood 14C measurements, confine the photosynthetic carbon fixation to around the midsummer.
Original languageEnglish
Article number3495
JournalNature Communications
Volume9
Issue number1
Number of pages8
ISSN2041-1723
DOIs
Publication statusPublished - 28 Aug 2018
MoE publication typeA1 Journal article-refereed

Bibliographical note

Correction:
Nature communications 10, article number: 1292 (2019)
DOI: 10.1038/s41467-019-09214-w

Fields of Science

  • 115 Astronomy, Space science
  • FINNISH LAPLAND
  • C-14
  • ATMOSPHERE
  • INCREASE
  • BE-10
  • RADIOCARBON
  • TROPOPAUSE
  • SIGNALS
  • CARBON
  • MODEL

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