| Project/Area Number |
08640548
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | Nagasaki University |
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Principal Investigator |
ARAO Kimio Nagasaki Univ., Faculty of Environmental Studies ; Prof., 環境科学部, 教授 (40039425)
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| Co-Investigator(Kenkyū-buntansha) |
NAKANE Shigekatsu Nagasaki University, Faculty of Fisheries ; Prof., 水産学部, 教授 (50001590)
FUJIYOSHI Yasushi Hokkaido Univ., Inst.of Low temperature Sci. ; Prof., 低温科学研究所, 教授 (40142749)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1997: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1996: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Meteorological rader / Convective rainfall / Nagasaki Peninsula / Effects of valley / Shimabara Peninsula / Volcanic debris flow |
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| Research Abstract |
The Chiji Valley at the Nagasaki Peninsula in Nagasaki Prefecture is a very deep valley which is open to the south direction, and can be inferred as a role of topographical effect of convective rainfall generation. The rain storms evoluted near the Nagasaki Peninsula often move towards to the Shimabara Peninsula and sometimes occure the velcanic debris flows around the Unzen-Fugendake Volcano.
The main purpose of this study is to observe the evolution and development process of the rain cells at the Nagasaki Peninsula. The results obtained in this study are as follows ;
(1) The line-shaped rain echoes, which extended from the Higashi-Nagasaki area to the Isahaya Bay region and lasted as long as ten hours or more, were observed by the RHI radar of Nagasaki University at July 2 and July 11 both in 1995. These very characteristic and significant rain echoes appeared under the same atmospheric condition that the warm and humid south wind from the sea prevails over Nagasaki area. This conditi
… More
on strongly suggests the enhancement of the vertical motion by a deep valley.
(2) The line-shaped and long-lasting echoes almost same as the above cases. were observed frequently in the monsoon seasons in l996 and 1997. All the atmospheric conditions ge*nerated these echoes can be characterized as the south wind at surface. In addition to this significant radar echoes, the scond and third line-shaped echoes with relatively weak intensity were observed in a parallel direction with the main echoes. Since these weak linear echoes are also corresponding to small valleys open to the south, the appearance of these second and third echoes strongly supports the hypothesis of the valley effects at the Nagasaki Peninsula.
3) The disastrous debris flows aroud Mt.Unzen were decreased according to the silence of the volcanic activity and the contruction of dams. In spite of this, the careful watch for heavy rainfalls can be still needed, because the vlcanic debris flows have taken place frequently in the riverbed. Less
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