日本地球惑星科学連合2023年大会

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セッション記号 A (大気水圏科学) » A-HW 水文・陸水・地下水学・水環境

[A-HW19] 水循環・水環境

2023年5月24日(水) 13:45 〜 15:15 105 (幕張メッセ国際会議場)

コンビーナ:榊原 厚一(信州大学理学部理学科)、岩上 翔(国立研究開発法人 森林研究・整備機構 森林総合研究所)、林 武司(秋田大学教育文化学部)、福士 圭介(金沢大学環日本海域環境研究センター)、座長:小槻 峻司(千葉大学 環境リモートセンシング研究センター)、榊原 厚一(信州大学理学部理学科)、岩上 翔(国立研究開発法人 森林研究・整備機構 森林総合研究所)、林 武司(秋田大学教育文化学部)、福士 圭介(金沢大学環日本海域環境研究センター)

13:45 〜 14:00

[AHW19-11] Stable isotopes of precipitation and moisture source determination using IsoGSM and backwards trajectory at Bandung, Indonesia

*Ilyas Nurfadhil Basuki1Kimpei Ichiyanagi1、Rusmawan Suwarman2Masahiro Tanoue3 (1.Kumamoto University、2.Bandung Institute of Technology 、3.Japan Meteorological Agency)


キーワード:Precipitation, Stable isotopes, Moisture, Backwards trajectory

A useful tracer for the atmospheric water cycle is stable water isotopes. Precipitation was collected at the Bandung Institute of Technology from late 2015 to mid-2016 and the stable isotopic ratios were analyzed at Kumamoto University. The analysis using the Water Isotope Analyzer (Picarro, L2020-i) gave results of stable oxygen isotope ratios between -18.4‰ and -2.0‰, stable hydrogen isotope ratios between -134.6‰ and -3.6‰, and d-excess values between 6.5‰ and 19.0‰. Oxygen isotope ratios were generally higher during the months of January, February, May, and June, and lower in March and April. In order to further analyze the results, the global 3D isotope-based IsoGSM model was used in this study. Simulated daily averaged stable isotope results had a decent fit with observations in the study area, with an R2 of 0.53. Backwards trajectory simulations were run to determine the possible moisture sources of Bandung precipitation, with the assumption that a trajectory represents the movement of moisture in the atmosphere. Based on the preliminary results of the simulations, there are multiple possible sources during different months. Most months had trajectories originating from the Indian Ocean and the South China Sea, while the months of December, January, and June also had trajectories originating from around Australia. Horizontal winds at 850 hPa level and cloud cover data were then used to determine the impact of monsoon winds and the Inter-Tropical Convergence Zone (ITCZ) on moisture movement, respectively. Westerly wind vector was quite strong near the study area from March to May, and cloud cover was high in the study area from March to May, and lower during other months. It was concluded that the wet monsoon season and the ITCZ generally cause a decrease in isotope values. Further analysis will be needed to determine the isotope characteristics at each moisture source, as well as the contribution amount of each source.