日本地球惑星科学連合2019年大会

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[J] 口頭発表

セッション記号 M (領域外・複数領域) » M-TT 計測技術・研究手法

[M-TT48] 地球化学の最前線

2019年5月26日(日) 15:30 〜 17:00 201A (2F)

コンビーナ:角野 浩史(東京大学大学院総合文化研究科広域科学専攻相関基礎科学系)、横山 哲也(東京工業大学理学院地球惑星科学系)、小畑 元(東京大学大気海洋研究所海洋化学部門海洋無機化学分野)、座長:角野 浩史小畑 元(東京大学大気海洋研究所)、横山 哲也(東京工業大学)

16:00 〜 16:15

[MTT48-09] Assessment of Northeastern Japan Tree-Ring Oxygen Isotopes for Reconstructing Early Summer Hydroclimate and Spring Arctic Oscillation

*坂下 渉1,2,3横山 祐典3宮原 ひろ子2阿瀬 貴博3オブラクタ スティーブン4大山 幹成5米延 仁志6 (1.国立研究開発法人森林研究・整備機構 森林総合研究所、2.武蔵野美術大学、3.東京大学大気海洋研究所、4.秋田大学、5.東北大学、6.鳴門教育大学)

キーワード:樹木年輪、酸素同位体、東北地方、北極振動、東アジア夏季モンスーン

The spring Arctic Oscillation (AO) significantly affects the subsequent summer rainfall in the East Asian Summer Monsoon (EASM) region, and analysis of meteorological data indicates this teleconnection strength varied on interdecadal timescales during the late 20th century. Tree-ring records may be able to extend the relatively short observational record, but the extent to which these proxy reconstructions correspond to AO variability has yet to be explored in this region. Therefore, we present new tree-ring cellulose oxygen isotope (δ18O) records from northeastern Japan (Akita, northern limit of EASM), spanning AD 1950 to 2003 which overlaps with the instrumental record. Tree-ring δ18O is used for reconstructing the past hydroclimate variability and allows us to consider whether tree-ring δ18O has the potential to clarify the longer-term interdecadal changes in the spring AO-EASM relationship. Measurements and analyses show that our tree-ring δ18O datasets have a significant negative correlation with May-June-July relative humidity, and the tree-ring δ18O in northeastern Japan also significantly correlates with the summer EASM index. Temporal comparisons between our record and observed monthly AO index indicate that reconstructed following early summer relative humidity significantly correlates to the previous March-April-May AO. This linkage changes on interdecadal timescales, and the linkage is relatively strong during early 1970s through early 1990s. Similar results are also obtained using a separate tree-ring δ18O record from a separate location about 200 km to the southeast, suggesting that tree-ring cellulose δ18O in northeastern Japan is indeed useful for better understanding the long-term teleconnection between the spring AO and EASM.