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

[PEM07-30] マウンダー極小期の宇宙線強度変動

*宮原 ひろ子¹、堀内 一穂²、門叶 冬樹³、加藤 和浩³、森谷 透³、横山 祐典⁴、松崎 浩之⁴、本山 秀明⁵、片岡 龍峰⁵ (1.武蔵野美術大学、2.弘前大学、3.山形大学、4.東京大学、5.国立極地研究所)

キーワード：マウンダー極小期, 宇宙線, 太陽活動, 太陽圏, 宇宙気候, 宇宙線生成核種

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.