Centennial-scale monsoon variation by using sediment cores in blackish lake

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K17775
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Geology
• Research Institution: Shinshu University
• Principal Investigator: Yamada Katsura 信州大学, 学術研究院理学系, 准教授 (80402098)
• Research Collaborator: SETO Koji 島根大学, エスチュアリー研究センター, 准教授 (60252897) ; IKEHARA Minoru 高知大学, 教育研究部自然科学部門理学系, 教授 (90335919) ; KUROKI Kentaro 信州大学, 理工学研究科, 院生 ; KOHARA Kazuma 信州大学, 理工学研究科, 院生 ; KUROMATU Kuniyoshi 信州大学, 理学部理学科地質科学科, 学生
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 東アジアモンスーン / 気候 / 完新世 / 貝形虫 / 酸素同位体比

Outline of Final Research Achievements

Climate in Japanese Islands are strongly affected by East Asian summer monsoon (EASM). We reconstructed centennial-scale East Asian summer monsoon intensity during the past 3000 years based on oxygen isotope ratio of ostracode shells, which are small crustaceans, in brackish lake, southwestern Japan. Three intervals were recognized on the basis of the EASM intensity, timing and cyclic periodicity. The 200 year periodicity was identified in East Asian summer monsoon records and atmospheric 14C relating to solar activities in the periods of BC800-BC100. No correlation between our data and other EASM records and sun activity during the periods of BC100-AD300. Further, common multi-centennial scaled cycles in EASM variations were identical in some area since AD300. These observations infer that sun activity affected to centennial scaled EASM variations in a restricted intervals.

Free Research Field

古生物学