Investigation of detailed water cycle processes in atmosphere and land surface using stable water isotope data assimilation system

2016 Fiscal Year Final Research Report

• Project/Area Number: 26289160
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Hydraulic engineering
• Research Institution: The University of Tokyo
• Principal Investigator: Yoshimura Kei 東京大学, 生産技術研究所, 准教授 (50376638)
• Co-Investigator(Kenkyū-buntansha): 金 元植 国立研究開発法人農業環境技術研究所, 大気環境研究領域, 主任研究員 (40414502)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 水同位体比 / 気候プロキシ / 千年再解析 / 蒸発散フラックス / データ同化 / 陸面過程 / 成分分離 / 蒸散寄与率

Outline of Final Research Achievements

In this project, we developed a new vapor isotope continuous measurement system to understand the land water cycle process in more detail. Compared to conventional mass spectrometric methods, by using laser spectroscopic technique, it is possible to increase the measurement frequency and precision of vapor isotope and moreover to dramatically improve the estimation precision and time resolution of the evapotranspiration isotope and transpiration fraction. Furthermore, due to portability and ease of management, it was succeeded in acquiring continuous data over three years from the test observation paddy. Based on the results, we developed a transpiration fraction estimation method applicable to the whole world, and estimated the value of 57±7% as the global mean. Regarding the transpiration fraction, various values were published ranging 20% to 90% in the past few years, which was a big controversy, but the value based on this observation data may settle the dispute.

Free Research Field

同位体気象学