TY - JOUR
T1 - Prolonged production of 14C during the ~660 BCE solar proton event from Japanese tree rings
AU - Sakurai, Hirohisa
AU - Tokanai, Fuyuki
AU - Miyake, Fusa
AU - Horiuchi, Kazuho
AU - Masuda, Kimiaki
AU - Miyahara, Hiroko
AU - Ohyama, Motonari
AU - Sakamoto, Minoru
AU - Mitsutani, Takumi
AU - Moriya, Toru
N1 - Funding Information:
We are deeply indebted to Dr. Kayo Suzuki and Dr. Yui Takahashi for basic preparations of the Choukai-Jindai cedar sample. We appreciate a reviewer for very important suggestion about data analytical methods. This work was supported by JSPS KAKENHI grant number JP10640245 and JP16H06005.
Publisher Copyright:
© 2020, The Author(s).
PY - 2020/12/1
Y1 - 2020/12/1
N2 - Annual rings record the intensity of cosmic rays (CRs) that had entered into the Earth’s atmosphere. Several rapid 14C increases in the past, such as the 775 CE and 994CE 14C spikes, have been reported to originate from extreme solar proton events (SPEs). Another rapid 14C increase, also known as the ca. 660 BCE event in German oak tree rings as well as increases of 10Be and 36Cl in ice cores, was presumed similar to the 775 CE event; however, as the 14C increase of approximately 10‰ in 660 BCE had taken a rather longer rise time of 3–4 years as compared to that of the 775 CE event, the occurrence could not be simply associated to an extreme SPE. In this study, to elucidate the rapid increase in 14C concentrations in tree rings around 660 BCE, we have precisely measured the 14C concentrations of earlywoods and latewoods inside the annual rings of Japanese cedar for the period 669–633 BCE. Based on the feature of 14C production rate calculated from the fine measured profile of the 14C concentrations, we found that the 14C rapid increase occurred within 665–663.5 BCE, and that duration of 14C production describing the event is distributed from one month to 41 months. The possibility of occurrence of consecutive SPEs over up to three years is offered.
AB - Annual rings record the intensity of cosmic rays (CRs) that had entered into the Earth’s atmosphere. Several rapid 14C increases in the past, such as the 775 CE and 994CE 14C spikes, have been reported to originate from extreme solar proton events (SPEs). Another rapid 14C increase, also known as the ca. 660 BCE event in German oak tree rings as well as increases of 10Be and 36Cl in ice cores, was presumed similar to the 775 CE event; however, as the 14C increase of approximately 10‰ in 660 BCE had taken a rather longer rise time of 3–4 years as compared to that of the 775 CE event, the occurrence could not be simply associated to an extreme SPE. In this study, to elucidate the rapid increase in 14C concentrations in tree rings around 660 BCE, we have precisely measured the 14C concentrations of earlywoods and latewoods inside the annual rings of Japanese cedar for the period 669–633 BCE. Based on the feature of 14C production rate calculated from the fine measured profile of the 14C concentrations, we found that the 14C rapid increase occurred within 665–663.5 BCE, and that duration of 14C production describing the event is distributed from one month to 41 months. The possibility of occurrence of consecutive SPEs over up to three years is offered.
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U2 - 10.1038/s41598-019-57273-2
DO - 10.1038/s41598-019-57273-2
M3 - Article
C2 - 31959822
AN - SCOPUS:85078254098
VL - 10
JO - Scientific Reports
JF - Scientific Reports
SN - 2045-2322
IS - 1
M1 - 660
ER -