| Project/Area Number |
16500644
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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 |
Geography
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| Research Institution | Tokyo Gakugei University |
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Principal Investigator |
TAKAHASHI Hideo Tokyo Gakugei University, Faculty of Education, Associate Professor, 教育学部, 助教授 (40202155)
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| Co-Investigator(Kenkyū-buntansha) |
NAKMURA Yasuko Tokyo Gakugei University, Faculty of Education, Assistant Professor, 教育学部, 講師 (20293003)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2004: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | Tokyo Metropolitan area / Short-duration heavy rainfall / Surface roughness / Building / Aerodynamic parameter / Sky view factor / Urban heat island / Convergence / 東京都区部 / 空気力学的粗度 / ゼロ面変位 / 風速分布 / 時間降水量分布 / 数値地表モデル / 強雨発現頻度 / 時間降水量 / 東京都心域 / 建築物高度 / 高層建築物 / 風向 / GIS |
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| Research Abstract |
In this research, relationships between the occurrence of summertime short-duration heavy rainfall and the urban surface structure in the Tokyo metropolitan area were analyzed in terms of climatology and urban morphology. The results can be summarized as follows :
1. The heavy rainfall area in the northern-western and southern area of central Tokyo tends to develop in its neighborhood during a short period, which indicates the characteristic feature of heavy rainfall in the urban area of Tokyo.
2. Local-scale differences in the occurrence frequency of heavy rainfall are distinct in the Tokyo ward area. The frequent heavy rainfall areas are found in the western and northern part of the Tokyo ward area. Heavy rainfall in former and latter areas tends to occur corresponding to easterly and southerly wind, respectively. These areas are located in the leeward of high-rise buildings such as Shinjuku and Ikebukuro. It is suggested that convergence of surface wind due to large surface roughness enhances the convective activity in the urban area.
3. The calculation method of sky view factor (SVF) by using digital surface model (DSM) was introduced, and the calculation of SVF over the Tokyo ward area was conducted. As the spatial representativeness of SVF at a given point is scarce, scale-up of SVF is required for the discussion on the relationship between urban heat island and SVF. The typical SVFs in the Tokyo ward area are estimated from SVF histogram of 1km×1km areas.
4. The aerodynamic parameters in the Tokyo ward area were computed by using DSM, and horizontal/vertical wind velocity distribution was evaluated. Large ascending wind appears Shinjuku-Meguro, Ikebukuro, etc., and the areas of ascending wind vary with wind directions. It is concluded that the local-scale differences in the occurrence frequency of heavy rainfall is strongly related to the surface roughness which high-rise buildings forms.
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