2007 Fiscal Year Final Research Report Summary
Comprehensive Study on Meso-Scale Precipitation System with Use of Stable Isotope Ratios of Water
| Project/Area Number |
17204041
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | Nagoya University |
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Principal Investigator |
NAKAMURA Kenji Nagoya University, Hydrospheric Atmospheric Research Center, Professor (20262917)
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| Co-Investigator(Kenkyū-buntansha) |
UYEDA Hiroshi Nagoya University, Hydrospheric Atmospheric Research Center, Professor (80184935)
HIYAMA Tetsuya Naeova University, Hydrospheric Atmospheric Research Center, Associate Professor (30283451)
ABE Osamu Nagoya University, Graduate School of Environmental Studies, Assistant Professor (00293720)
SHINODA Taro Naeova University, Hydrospheric Atmospheric Research Center, Assistant Professor (50335022)
HIGUCHI Atsushi Chiba University, Center for Environmental Remote Sensing, Associate Professor (90324384)
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| Project Period (FY) |
2005 – 2007
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| Keywords | Meso-Scale Precipitation System / Isotopic Composition of Precipitation / Precipitation System / Water Vapor Amount / Drop size distribution |
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| Research Abstract |
Analyses of oxygen isotopic composition of precipitation with several minutes intervals and meteorological observation by a polarimetric Doppler radar and GPS sondes were conducted during rainy season in 2004 at Okinawa. Large isotopic variation observed in event-to-event precipitation, in spite of the same vapor origins, implied that precipitation type (convective or stratiform) significantly affected isotopic values. Moreover, isotopic variation during convective precipitation was strongly affected by dryness in the middle troposphere before development of the convective system.
Based on the intra-event analyses of isotopic variation, it was found that the development stage of convective systems strongly related to isotopic values. Isotopic values showed gradual decreasing trends in the developing stage, whereas they showed V-shape patterns in the dissipating stage of convective systems. These V-shape patterns could be caused by significant evaporation of falling raindrops.
For quantit
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ative evaluation of isotopic change during raindrop falling, "isotopic exchange model of between raindrop and vapor for each size" was developed. As a result of sensitivity experiment, isotopic shifts were larger in smaller raindrops or at lower relative humidity. It could be demonstrated that relative humidity below cloud base was a significant controlling factor for the isotopic values of bulk(weighted mean)precipitation.
Drop-size distribution of isotopic values in precipitation, which was expected from the model simulation, was observed by a raindrop collection method using liquid nitrogen and the isotope analysis for micro-liter of water samples. All observed results of three rainfall events at Nagoya in 2007 showed that higher hydrogen and oxygen isotopic values were found in smaller raindrops, which were consistent with the model calculation.
Our results clearly indicate that the difference of cloud types and the evaporation effect during falling raindrops should be taken into account for the variation of isotopic composition of precipitation, not only the difference of vapor sources as discussed previously. Less
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Research Products
(30 results)
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[Journal Article] Review and Perspective on the Water Cycle Processes using Stable Isotope of Water2008
Author(s)
HIYAMA, Tetsuya, Osamu, ABE, Naoyuld, KURITA, Koji, FUJITA, Kenichi, IKEDA, Shigemasa, HASHIMOTO, Maid, TSUJIMURA, Tsutomu, YAMANAKA
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Journal Title
J. Japan Soc. Hydrol. & Water Resour Vol.21, No.2
Pages: 158-176
Description
「研究成果報告書概要(欧文)」より
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[Presentation] 雨滴の粒径別同位体比分析2007
Author(s)
江口景子・阿部理・檜山哲哉
Organizer
2007年度日本質量分析学会同位体比部会
Place of Presentation
札幌
Year and Date
2007-10-24
Description
「研究成果報告書概要(和文)」より
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