Japan Geoscience Union Meeting 2022

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[E] Oral

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

[P-EM09] Space Weather and Space Climate

Mon. May 23, 2022 10:45 AM - 12:15 PM 302 (International Conference Hall, Makuhari Messe)

convener:Ryuho Kataoka(National Institute of Polar Research), convener:Antti A Pulkkinen(NASA Goddard Space Flight Center), Kaori Sakaguchi(National Institute of Information and Communications Technology), convener:Daikou Shiota(National Institute of Information and Communications Technology (NICT)), Chairperson:Antti A Pulkkinen(NASA Goddard Space Flight Center), Daikou Shiota(National Institute of Information and Communications Technology (NICT))

10:45 AM - 11:00 AM

[PEM09-07] Recurrent large-scale solar proton events before the onset of the Wolf grand solar minimum indicated by carbon-14 content in tree rings

*Hiroko Miyahara1, Fuyuki Tokanai2, Toru Moriya2, Mirei Takeyama2, Hirohisa Sakurai2, Motonari Ohyama3, Kazuho Horiuchi4, Hideyuki Hotta5 (1.Musashino Art University, 2.Yamagata University, 3.Tohoku University, 4.Hirosaki University, 5.Chiba University)

Keywords:solar proton events, grand solar minimum, carbon-14

Based on the analyses of cosmic-ray induced radionuclide (carbon-14) in tree rings, a number of past large-scale solar proton events have been discovered. While the largest events such as in 774–775 CE cause more than 1 % increase of carbon-14 content in tree rings and can be significantly detected by the typical precision of accelerator mass spectrometry (0.2-0.3%), it has been difficult to detect smaller but possibly more frequent events. Thus, the frequency or any characteristics of such relatively small events are largely unknown. In this paper, we report on our attempt to improve the precision of carbon-14 analyses using the accelerator mass spectrometry and on the three solar proton events found just before the Wolf grand solar minimum.