| Project/Area Number |
09440167
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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 | Univ. of Tokyo |
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Principal Investigator |
YAMASAKI Masanori Graduate School of Science, Univ. of Tokyo, Prof., 大学院・理学系研究科, 教授 (40242101)
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| Co-Investigator(Kenkyū-buntansha) |
TSUBOKI Kazuhisa Institute of hydrometeor and Atmospheric Science, Univ. of Nagoya, Associate Prof., 大気水圏科学研究所, 助教授 (90222140)
NAKAMURA Kozo Ocean Research Institute, Univ. of Tokyo, Assistant, 海洋研究所, 助手 (20143547)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥6,600,000 (Direct Cost: ¥6,600,000)
Fiscal Year 1999: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1998: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1997: ¥3,400,000 (Direct Cost: ¥3,400,000)
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| Keywords | baiu front / tropical cyclone / organization of convection / parameterization / メソ降水系 |
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| Research Abstract |
A numerical model was developed that can well simulate Baiu fronts and tropical cyclones and mesoscale organized convection in these, phenomena. In order to improve cumulus-scale parameteriztion in the mesoscale-convection- resolving- model (Yamasaki, 1986), cumulus-scale cloud water was treated as a prognostic variable. Another improvement is that an assumption of a very small cloud fraction, which has been used in cloud parameterization of Arakawa and Schubert (1974), was not used because mesoscale organization of cumulus convection is treated. The model was applied to cloud clusters associated with baiu fronts and tropical cyclones and compared with results from several models with different parameterization schemes proposed in the past. It was found that a more realistic simulation could be made with a new model for cloud dusters associated with the baiu front and mesoscale structure of tropical cyclones.
As for interaction of a baiu front with a tropical cyclone, numerical experiments were performed for two cases with and without a tropical cyclone to the south of the baiu front. The rainfall associated with the baiu front was found to be enhanced by the presence of a tropical cyclone. The process and mechanism for its enhancement were clarified.
Numerical experiments were also made with the use of a non-hydrostatic cumulus-scale resolving model. By improving the ice phase parameterization, particularly generation rates and processes of the cloud ice and graupel, an eyewall of a tropical cyclone was better simulated. Another cloud model that can be efficiently used for a pararell computer, was developed. The model could simulate successfully a supercell associated with a tropical cyclone and a tornado in it.
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