Solar superstorm of AD 774 recorded subannually by Arctic tree rings

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Uusitalo , J , Arppe , L , Hackman , T , Helama , S , Kovaltsov , G , Mielikäinen , K , Mäkinen , H , Nöjd , P , Palonen , V , Usoskin , I & Oinonen , M 2018 , ' Solar superstorm of AD 774 recorded subannually by Arctic tree rings ' , Nature Communications , vol. 9 , no. 1 , 3495 . https://doi.org/10.1038/s41467-018-05883-1

Title: Solar superstorm of AD 774 recorded subannually by Arctic tree rings
Author: Uusitalo, J.; Arppe, L.; Hackman, T.; Helama, S.; Kovaltsov, G.; Mielikäinen, K.; Mäkinen, H.; Nöjd, P.; Palonen, V.; Usoskin, I.; Oinonen, M.
Contributor organization: Finnish Museum of Natural History
Natural Sciences Unit
Department of Physics
Date: 2018-08-28
Language: eng
Number of pages: 8
Belongs to series: Nature Communications
ISSN: 2041-1723
DOI: https://doi.org/10.1038/s41467-018-05883-1
URI: http://hdl.handle.net/10138/241214
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.Recently, a rapid increase in radiocarbon (C-14) was observed in Japanese tree rings at AD 774/775. Various explanations for the anomaly have been offered, such as a supernova, a gamma-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 C-14 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 C-14 poleward increase, in accord with the solar origin of the event. Furthermore, both annual C-14 data and carbon cycle modelling, and separate earlywood and latewood C-14 measurements, confine the photosynthetic carbon fixation to around the midsummer.
Description: Correction: Nature communications 10, article number: 1292 (2019) DOI: 10.1038/s41467-019-09214-w
Subject: 115 Astronomy, Space science
FINNISH LAPLAND
C-14
ATMOSPHERE
INCREASE
BE-10
RADIOCARBON
TROPOPAUSE
SIGNALS
CARBON
MODEL
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion
Funder: Unknown funder
Grant number:


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