Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Oral

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS10] Paleoclimatology and paleoceanography

Wed. May 23, 2018 3:30 PM - 5:00 PM A07 (Tokyo Bay Makuhari Hall)

convener:Yusuke Okazaki(Department of Earth and Planetary Sciences, Graduate School of Science, Kyushu University), Atsuhiko Isobe(Research Institute for Applied Mechanics, Kyushu University), Akihisa Kitamura(静岡大学理学部地球科学教室, 共同), Masaki Sano(Faculty of Human Sciences, Waseda University), Hitoshi Hasegawa(Faculty of Science and Technology, Kochi University), Akira Oka(Atmosphere and Ocean Research Institute, The University of Tokyo), Michinobu Kuwae(Center for Marine Environmental Studies), Chairperson:Sano Masaki

3:45 PM - 4:07 PM

[MIS10-14] Cosmic ray events shown in 14C data

★Invited Papers

*Fusa Miyake1 (1.Institute for Space-Earth Environmental Research, Nagoya University)

Keywords:Radiocarbon, 14C spike, Annual cosmic ray event

Cosmic rays falling on the Earth mainly come from outside the solar system (Galactic Cosmic Ray: GCR ) and the sun (Solar Cosmic Ray: SCR). Incoming cosmic rays interact with the atmosphere, whence cosmic rays produce cosmogenic nuclides such as 14C. Carbon-14 is oxidized to form 14CO2 shortly thereafter its production, and is incorporated in tree-rings. Therefore, 14C contents in tree rings would be a proxy of past cosmic ray intensities.

Several past cosmic ray increase events including the AD 775 event have been detected as a rapid increase of 14C contents in tree rings, namely “14C spike”. It is considered that an origin of these events is an extreme Solar Proton Event (SPE) originated from large solar flares and coronal mass ejections. An existence of 14C spikes is important not only to understand the solar activities but also to offer an annual time marker in 14C data which can be applied to an annual radiocarbon dating and a dendrochronology. Recently, such application studies have been performed, e.g. annual age determination of a volcanic eruption of Mt. Baitoushan (AD 946) and historical wood sample of a Switzerland chapel using the AD 775 event.

In this presentation, I will introduce detected rapid 14C increase events, their origins, and application studies of 14C spikes.