2018 Fiscal Year Final Research Report
A study on the torrential rainfall over the Japan region through Atmospheric River connecting tropics and midlatitudes
| Project/Area Number |
15H02132
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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 | The University of Tokyo |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
河谷 芳雄 国立研究開発法人海洋研究開発機構, 統合的気候変動予測研究分野, 主任研究員 (00392960)
重 尚一 京都大学, 理学研究科, 准教授 (60344264)
廣田 渚郎 国立研究開発法人国立環境研究所, 地球環境研究センター, 研究員 (30750616)
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| Research Collaborator |
HORINOUCHI Takeshi
YOKOYAMA Chie
YOSHIMURA Kei
HIROTA Nagio
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| Project Period (FY) |
2015-04-01 – 2018-03-31
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| Keywords | 極端降水 / Atmospheric River / 切離低気圧 / 亜熱帯ジェット / 広島豪雨 / 2018年7月豪雨 / TRMM降雨レーダ / 雲解像モデル実験 |
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| Outline of Final Research Achievements |
We renewed understandings of roles of upper tropospheric large-scale circulation upon heavy rainfalls over Japan in warm seasons. First, we clarified effects of interplay between an Atmospheric River and an upper-level cut-off-low upon localized heavy rainfalls, with data analyses and numerical experiments of the Hiroshima Rainfall Event in 2014, and confirmed it statistically with a long-term data. Next, we used 3D precipitation radar data from TRMM and GPM satellites, to quantitatively relate rainfall characteristics to large-scale conditions; jet streams and stability. We also statistically extracted ‘extreme rainfalls (ER)’ and ‘extreme convections’ with the TRMM data, and compared their rainfall characteristics and their environments. A torrential rainfall event in July 2018 was studied in this context. The event was an extreme of the ER, with moderate storm heights and a wide area, occurred in a very wet and relatively stable AR-like condition in front of a stagnated trough.
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| Free Research Field |
数物系科学
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| Academic Significance and Societal Importance of the Research Achievements |
近年、降水の激甚化が社会問題となっている。現在の防災の面でも、将来の気候変動に対する適応策のためにも、豪雨の特性、大規模場環境場、発生の仕組みを精確に把握する必要がある。本研究は、日本域暖候期の豪雨について、特に過去に見過ごされてきた上部対流圏の大規模循環とそれに伴うAtmospheric River（AR）と呼ばれる対流圏の湿った空気の流れの役割を明らかにした。高機能衛星観測による降雨特性の統計や数値実験を通した新しい知見は、学術的に高い価値を持つと共に、広島豪雨や2018年7月豪雨の理解に結び付き、豪雨に対する防災対策、および、将来への社会の備えに対して社会的な貢献が期待される。
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