Japan Geoscience Union Meeting 2014

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Poster

Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS30_28PO1] Paleoclimatology and paleoceanography

Mon. Apr 28, 2014 6:15 PM - 7:30 PM Poster (3F)

Convener:*Yamada Kazuyoshi(School of Human Sciences, Waseda University), Minoru Ikehara(Center for Advanced Marine Core Research, Kochi University), Tomohisa Irino Tomohisa(Faculty of Environmental Earth Science, Hokkaido University), Yusuke Okazaki(Department of Earth and Planetary Sciences, Graduate School of Science, Kyushu University), Ikuko Kitaba(Kobe University Research Center For Inland Seas), Akihisa Kitamura(Institute of Geosciences, Faculty of Science, Shizuoka University), Masaki Sano(Research Institute for Humanity and Nature), Ryuji Tada(Department of Earth and Planetary Science, Graduate School of Science, The Univeristy of Tokyo), Masakazu Yoshimori(Atmosphere and Ocean Research Institute, University of Tokyo)

6:15 PM - 7:30 PM

[MIS30-P01] A tree-ring oxygen isotope chronology from Yakushima Island and its dendroclimatic potential

*Masaki SANO1, Koh YASUE2, Katsuhiko KIMURA3, Takeshi NAKATSUKA1 (1.Research Institute for Humanity and Nature, 2.Shinshu University, 3.Fukushima University)

Keywords:tree ring, oxygen isotope ratios, Yakushima Island, monsoon

Recent progress in isotope dendroclimatology showed that tree-ring oxygen isotopes are a promising proxy to reconstruct past precipitation and/or relative humidity. In the present study, we developed a 300-year tree-ring oxygen isotope chronology using Japanese cedar (Cryptomeria japonica) growing in Yakushima Island, southern Japan, and explored its dendroclimatic potential. Two tree samples that were crossdated by visually matching ring-width variations were used for oxygen isotopic analysis. The resulting oxygen isotope series for the period 1700-2009 C.E. were highly correlated with each other (r = 0.68), indicating that common signals related to local climate are preserved in these data. Both the delta-18O series were individually normalized to have zero mean and unit variance, and the resulting series were averaged to build the final chronology. Response analysis with monthly climatic records (temperature, precipitation and relative humidity) from the Kagoshima station revealed that tree-ring delta-18O was primarily controlled by relative humidity and precipitation in the summer season (May-September). Perhaps the most striking feature of the delta-18O chronology is a significant increasing trend over the 20th century, indicating a decrease in summer relative humidity in the study region. We will present an extended version of the tree-ring delta-18O chronology over the past 1000 years or so.