1994 Fiscal Year Final Research Report Summary
Study on the orographic enhancement of rainfall
| Project/Area Number |
04452071
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
気象・海洋・陸水学
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| Research Institution | Nagoya University |
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Principal Investigator |
TAKEDA Takao Nagoya University, Institute for Hydrospheric-Atmospheric Sciences, Professor, 大気水圏科学研究所, 教授 (60022604)
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| Co-Investigator(Kenkyū-buntansha) |
SAITO Kazuo Meteorological Research Institute, Forecast Research Division, Research Scientis, 予報研究部, 主任研究官 (70391224)
KATO Kuranoshin Nagoya University, Institute for Hydrospheric-Atmospheric Sciences, Assistant Pr, 大気水圏科学研究所, 助手 (90191981)
FUJIYOSHI Yasushi Nagoya University, Institute for Hydrospheric-Atmospheric Sciences, Associate Pr, 大気水圏科学研究所, 助教授 (40142749)
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| Project Period (FY) |
1992 – 1994
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| Keywords | orographic heavy rainfall / doppler-radar observation / local wind / numerical simulation / band-like cumulonimbus clouds / Owase area / orographic enhancement of rainfall |
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| Research Abstract |
Orographic effect on the evolution of precipitating clouds were obsserved by doppler-radars in the region around Owase in the Kii Peninsula during the pcriod of July to October. Radar observation revealed interesting facts that when easterly wind was predominant at low levels, precipitating clouds of low top formed several 10km off the coast of Owase in the horizontal convergence zone caused by orographic effect and they stayd for a long time. In this situation cumulonimbus clouds, which developed over the sea and landed the peninsula, showed the intensification of precipitation before landing and after having landed.
Orographic effect on the three-dimensional structure of airflow over the Kii Peninsula and its surrounding region was simulated by a non-hydro-static numerical model. In the predominance of easterly wind at low levels, upcurrent was caused by orographic effect in the southeastern slope of the peninsula and it showed the largest intensity in the deeper inland area in the case of strong wind than the case of weak wind, and another upcurrent appeared over the sea though its appearance was dependent on the speed of ambient wind. In the real atmosphere traveling cumulonimbus clouds often indicated orographic enhancement of precipitation around these numerically simulated upcurrent areas. However, the most intensive orographic enhancement of convective precipitation in landing is located rather in the deeper inland than that of numerically simulated precipitation area.
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