2017 Fiscal Year Final Research Report
Variations in the East Asian summer monsoon for the last 400 ky based on foraminiferal Mg/Ca and oxygen isotope in the northern East China Sea
| Project/Area Number |
15K21656
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Environmental dynamic analysis
Geology
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| Research Institution | National Museum of Nature and Science, Tokyo |
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Principal Investigator |
Kubota Yoshimi 独立行政法人国立科学博物館, 地学研究部, 研究員 (80710946)
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| Research Collaborator |
HOLBOURN Ann
CLEMENS Steven
KIMOTO Katsunori
SAGAWA Takuya
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| Project Period (FY) |
2015-04-01 – 2018-03-31
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| Keywords | アジアモンスーン / 氷期間氷期サイクル / 浮遊性有孔虫 / Mg/Ca / 酸素同位体比 / 塩分復元 |
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| Outline of Final Research Achievements |
We reconstructed oxygen isotope (δ18O )of seawater by using Mg/Ca and δ18O of planktic foraminifera for the last 400 k in the northern East China Sea in order to understand orbital scale East Asian summer monsoon variability. As a results, unlike Yangtze River Valley speleothem δ18O, dominated almost exclusively by precession-band (23-ky) cyclicity, local seawater δ18O is dominated by eccentricity (100-ky) and obliquity (41-ky) cycles, with almost no precession-scale variance.. These results, consistent with records outside the Yangtze River Valley, suggest that East Asian monsoon rainfall is more sensitive to greenhouse gas and high latitude ice sheet forcing than to direct insolation forcing.
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| Free Research Field |
古気候・古海洋学
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