| Project/Area Number |
22340137
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 |
YASUNARI Tetsuzo 名古屋大学, 地球水循環研究センター, 特任教授 (80115956)
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| Co-Investigator(Kenkyū-buntansha) |
SATO Masaki 東京大学, 大気海洋研究所, 教授 (00255142)
HAYASHI Taiichi 京都大学, 防災研究所, 准教授 (10111981)
SATO Tomonori 北海道大学, 地球環境科学研究科, 准教授 (10512270)
SATOMURA Takehiko 京都大学, 大学院・理学研究科, 教授 (20273435)
FUJINAMI Hatsuki 名古屋大学, 地球水循環研究センター, 助教 (60402559)
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| Co-Investigator(Renkei-kenkyūsha) |
MURATA Fumie 高知大学, 理学部, 助教 (60399326)
FUKUTOMI Yoshiki 独立行政法人海洋研究開発機構, 地球環境変動領域, 主任研究員 (30392963)
TAKAHASHI Hiroshi 首都大学東京, 都市環境科学研究科, 助教 (50397478)
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| Project Period (FY) |
2010 – 2012
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| Project Status |
Completed (Fiscal Year 2012)
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| Budget Amount *help |
¥18,590,000 (Direct Cost: ¥14,300,000、Indirect Cost: ¥4,290,000)
Fiscal Year 2012: ¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000)
Fiscal Year 2011: ¥5,980,000 (Direct Cost: ¥4,600,000、Indirect Cost: ¥1,380,000)
Fiscal Year 2010: ¥7,150,000 (Direct Cost: ¥5,500,000、Indirect Cost: ¥1,650,000)
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| Keywords | アジアモンスーン / 降水 / 季節内変動 / 準 2 週間周期変動 / 気候 / 降水変動 / 準2週間変動 / 準2週間変動(QBW) / バングラデシュ / アッサム / 日周期変動 / 経年変動 / 準2週間周期変動(QBW) |
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| Research Abstract |
This study elucidated a process of distinct rainfall fluctuation related to quasi-biweekly Oscillation (QBW) over Himalaya-Assam-Bangladesh (HAB) region, where one of the heaviest rainfall is observed in the world, by means of data analysis and a numerical simulation. QBW in rainfall became a dominant mode of intraseasonal oscillation since 1980s around Bangladesh. QBW in rainfall over HAB region is most active, especially in Meghalaya plateau and the western coast of Myanmar, in land areas of Asian monsoon. In active (break) phase of rainfall in QBW in the HAB region, a low-level westerly/southwesterly (easterly/southeasterly) is dominated there. The large zonal wind fluctuation is induced by westward propagating n=1 equatorial Rossby wave with a wave length of ~6000 km. Rainfall in active phase of QBW often shows a remarkable diurnal variation around the Meghalaya plateau.The variation is caused by diurnal variation of low-level jet around 900 hPa. Thestrong low-level flow transports abundant moisture to the southern slope of the Meghalaya Plateau during the active period, which triggers forced lifting and brings orographic rainfall. However, low-level wind during the inactive period is too weak to induce orographic rainfall. Thus, the distinct QBW in HAB region is strongly enhanced locally (~500Km) by the topographical features although atmospheric circulation causing the ISO has horizontal scale of ~6000 Km.
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