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: University of Helsinki, Finnish Museum of Natural History
University of Helsinki, Finnish Museum of Natural History
University of Helsinki, Department of Physics
University of Helsinki, Natural Resources Institute Finland
University of Helsinki, Department of Physics
University of Helsinki, Finnish Museum of Natural History
Date: 2018-08-28
Language: eng
Number of pages: 8
Belongs to series: Nature Communications
ISSN: 2041-1723
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.
Subject: 115 Astronomy, Space science
FINNISH LAPLAND
C-14
ATMOSPHERE
INCREASE
BE-10
RADIOCARBON
TROPOPAUSE
SIGNALS
CARBON
MODEL
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