Japan Geoscience Union Meeting 2015

Presentation information

International Session (Oral)

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

[P-EM07] Space Weather, Space Climate, and VarSITI

Mon. May 25, 2015 4:15 PM - 6:00 PM 302 (3F)

Convener:*Ryuho Kataoka(National Institute of Polar Research), Yusuke Ebihara(Research Institute for Sustainable Humanosphere, Kyoto University), Yoshizumi Miyoshi(Solar-Terrestrial Environement Laboratory, Nagoya University), Toshifumi Shimizu(Institute of Space and Astronautical Science, JAXA), Ayumi Asai(Unit for Synergetic Studies of Space, Kyoto University), Hidekatsu Jin(National Institude of Information and Communications Technology), Tatsuhiko Sato(Japan Atomic Energy Agency), Kanya Kusano(Solar-Terrestrial Environment Laboratory, Nagoya University), Hiroko Miyahara(College of Art and Design, Musashino Art University), Takuji Nakamura(National Institute of Polar Research), Kazuo Shiokawa(Solar-Terrestrial Environment Laboratory, Nagoya University), Kiminori Itoh(Graduate School of Engineering, Yokohama National University), Chair:Yusuke Ebihara(Research Institute for Sustainable Humanosphere, Kyoto University)

5:30 PM - 5:45 PM

[PEM07-30] Variation of the intensity of galactic cosmic rays during the Maunder Minimum

*Hiroko MIYAHARA1, Kazuho HORIUCHI2, Fuyuki TOKANAI3, Kazuhiro KATO3, Toru MORIYA3, Yusuke YOKOYAMA4, Hiroyuki MATSUZAKI4, Hideaki MOTOYAMA5, Ryuho KATAOKA5 (1.Musashino Art Univ., 2.Hirosaki Univ., 3.Yamagata Univ., 4.The Univ. of Tokyo, 5.NIPR)

Keywords:Maunder Minimum, cosmic rays, solar activity, heliosphere, space climate, cosmogenic nuclide

Variations of the galactic cosmic-ray flux during the Maunder Minimum (AD1645-1715) are examined based on carbon-14 in tree rings and beryllium-10 in ice cores. Variations of beryllium-10 content in ice cores have suggested that the flux of galactic cosmic rays have increased by ~40 percent for about one year around every other solar cycle minima, when solar dipole magnetic field was negative. Periodicity of the events is ~26-28 years, corresponding to the Hale cycle during the Maunder Minimum. These extreme enhancements of cosmic rays are suggested to be possibly caused by a change in the large scale structure of heliospheric magnetic field, associated with extremely weakened solar activity. To obtain more reliable ages for those events, we have been also measuring the carbon-14 content in tree rings dated by dendro-chronology.