| Project/Area Number |
11219203
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | Kyoto University |
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Principal Investigator |
YODEN Shigeo Kyoto University, Department of Geophysics, Professor, 大学院・理学研究科, 教授 (30167027)
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| Co-Investigator(Kenkyū-buntansha) |
MUKOUGAWA Hitoshi Disaster Prevention Research Institute, Associate Professor, 防災研究所, 助教授 (20261349)
HORINOUCHI Takeshi Radio Science Center for Space and Atmosphere, Research associate, 宙空電波科学研究センター, 助手 (50314266)
NAITO Yoko Department of Geophysics, Research associate, 大学院・理学研究科, 助手 (50324603)
USHIMARU Shinji Numazu Inst. Tech., Associate Professor, 電子制御工学科, 助教授 (70249796)
ISHIOKA Keiichi Univ. of Tokyo, Grad. School Math. Sci., Associate Professor, 大学院・数理学研究科, 助教授 (90292804)
SATO Kaoru Arctic Environment Research Center, National Institute of Polar Research, Associate Professor (90251496)
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| Project Period (FY) |
1999 – 2002
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| Keywords | large-scale atmospheric waves / material transport / interannual variation / planetary waves / baroclinic waves / gravity waves / equatorial OBO / stratospheric sudden warming |
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| Research Abstract |
Nonlinear behaviors of large-scale atmospheric waves in the troposphere and the stratosphere were investigated with a hierarchy of numerical models, which we have been developed and used. Material transport processes associated with these waves were also studied with some tracer models. Seasonal dependence, interannual variations, and trends of the wave behaviors were also clarified by analyzing long records of numerical time-integrations and global observation data.
1. Model development : A numerical library to solve geophysical fluid motions in some typical geometries efficiently in supercomputers has been developed. As application tests of the models, 2-D decaying turbulence on a rotating sphere and gravity wave radiation in a rotating shallow water system are investigated.
2. Planetary waves : A global circulation model with simplified physical processes was used to investigate the effects of the equatorial QBO winds on planetary waves and mean meridional circulation in the winter he
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misphere. It was demonstrated that large sample method based on long enough data is a powerful tool to show the statistical significance of the QBO effects. In order to study horizontal mixing and transport barrier in winter stratosphere, assimilated data for 9 years from 1990 were used to do local Lyapunov stability analysis and compute Lagrange trajectories of many particles. Interannual variations of the mixing were quantified with these analyzes.
3. Baroclinic waves : Long time integrations of an atmospheric GCM were done with an idealized SST to investigate the dynamics of localized storm tracks. It was found that the most important factor to determine the localization is nonzonal (west-east) component of the meridional gradient of SST in mid-latitudes.
4. Equatorial gravity waves : Generation, propagation and breaking processes of convectively generated gravity waves were firstly simulated with a meso-scale non-hydrostatic numerical model from the surface to the lower thermosphere (about 100 km height). An estimation method of convectively generated waves in the equatorial region based on satellite observations of IR radiation was developed and tested. Less
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