JpGU-AGU Joint Meeting 2020

Presentation information

[E] Oral

P (Space and Planetary Sciences ) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM17] Space Weather and Space Climate

convener:Ryuho Kataoka(National Institute of Polar Research), Antti A Pulkkinen(NASA Goddard Space Flight Center), Kanya Kusano(Institute for Space-Earth Environmental Research, Nagoya University), Kaori Sakaguchi(National Institute of Information and Communications Technology)

[PEM17-13] 14C during the ~660 BCE solar proton event from Japanese tree rings

★Invited Papers

*Hirohisa Sakurai1, Fusa Miyake2, Fuyuki Tokanai1, Kazuho Horiuchi3, Hiroko Miyahara4, Kimiaki Masuda2, Motonari Ooyama5, Minoru Sakamoto6, Takumi Mitsutani7, Toru Moriya1 (1.Faculty of Science, Yamagata University, 2.ISEE, Nagoya University,, 3.Hirosaki University, 4.Graduate School of Science and Technology, Hirosaki University, 5.Botanical Gardens, Tohoku University, 6.National Museum of Japanese History, 7.National Institutes for Cultural Heritage, Nara National Research Institute for Cultural Properties)

Keywords:14C, ~660 BCE event, SPE

Annual rings record the intensity of cosmic rays 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 using an 11-Box model of carbon cycle, 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 3.4 years. The possibility of occurrence of consecutive SPEs over up to three years is offered.