| Project/Area Number |
12640417
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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 | KYOTO UNIVERSITY (2002)
Hokkaido University (2000-2001) |
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Principal Investigator |
MUKOUGAWA Hitoshi DISASTER PREVENTION RESEARCH INSTITUTE, ASSOCIATE PROFESSOR, 防災研究所, 助教授 (20261349)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2002: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | storm track / baroclinic disturbance / planetary wave / time-mean circulation / extratropical SST distribution / diabetic heating / atmospheric general circulation model / 中緯度SST分析 / 水惑星実験 / エネルギー解析 / 定在波 / 熱帯SST分布 / 対流圏時間平均循環場 |
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| Research Abstract |
In the wintertime northern hemispheric circulations, storm tracks where the activity of synoptic-scale disturbances is enhanced in the extratropical troposphere are zonally localized over the Pacific and the Atlantic. However, the dynamical mechanism of the zonally localization of storm tracks has not been fully established. Their role on the formation of the time-mean tropospheric circulation is also controversial. In particular, the relevance of extratropical sea surface temperature (SST) distribution to the storm track formation, which is central to understand the dynamics of decadal climate variability remains unclear. In this study, we proceeded a series of long-term integration of an atmospheric general circulation model (AGCM) (CCSR/NIES AGCM with horizontal resolution of T42 and 20 vertical levels) to reveal the dynamics of storm track and its feedback onto the time-mean circulation. The numerical experiments were conducted under a perpetual January condition without topography by specifying idealized land-sea and SST distribution. The following results were obtained:
1 In the absence of topographically forced Rossby waves, the zonal asymmetry of the low-level baroclinicity formed by the underlying SST distribution is indispensable to localize the storm, while that in the upper tropospheric circulation, such as subtropical jet and barotropic energy conversion, plays only a secondary role.
2 The zonal asymmetry of the low-level baroclinicity is maintained by stationary planetary waves forced by the diabatic heating distribution associated with the storm track.
3 Thus, the positive feedback mechanism between synoptic-scale eddies and planetary waves through the diabatic heating plays the most important role in localizing the storm track in the zonal direction.
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