| Project/Area Number |
07640574
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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 | KYUSHU UNIVERSITY |
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Principal Investigator |
HIROOKA Toshihiko Faculty of Science, KYUSHU UNIVERSITY Associate Professor, 理学部, 助教授 (90253393)
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| Co-Investigator(Kenkyū-buntansha) |
MIYOSHI Yasunobu Faculty of Science, KYUSHU UNIVERSITY Research Associate, 理学部, 助手 (20243884)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1996: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1995: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Rossby wave / free wave / middle atmosphere / satellite data / general clrculation model |
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| Research Abstract |
Normal mode Rossby waves are westward traveling free waves of the atmosphere with characteristic periods of 5-20 days. The present study consists of analyzes of observed data obtained by satellite measurements and numerical simulation by the use of general circulation models (GCMs).
1 Results based on analyzes of observed data :
(1) Global structures of 5-day and 10-day waves are firstly shown in the mesosphere by the use of UARS/ISAMS data obtained through NASA.
(2) Both the 5-day and 10-day waves are gradually with height in the upper mesosphere ; nonetheless 10-day waves have large amplitudes in the winter hemisphere.
2 Results based on GCM simulation :
(1) Simulated 5-day waves have vertical and horizontal structure very similar to that of observed ones and appear irregularly with a lifetime of about one month.
(2) Detailed analyzes for 5-day waves and precipitations show the evidence that 5-days wave activities are inclined to be largely enhanced when anomalies in the precipitation field of zonal wavenumber 1 are large with a westward period of 5 days.
(3) 5-day waves also appear in conditions of no mountains and/or no land-sea contrast ; hence these are probably unimportant for excitation of the waves. However, 5-day wave activities are significantly weak in case of removal of the latent heat release.
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