| Project/Area Number |
04452072
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
気象・海洋・陸水学
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
HIROTA Isamu KYOTO UNIV., FAC.SCI., PROFESSOR, 理学部, 教授 (70025485)
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| Co-Investigator(Kenkyū-buntansha) |
SHIOTANI M KYOTO UNIV., FAC.SCI., RA., 理学部, 助手 (50192604)
SAKAI S KYOTO UNIV., FAC.I.H.S., AP., 総合人間学部, 助教授 (30144299)
YODEN S KYOTO UNIV., FAC.SCI., AP., 理学部, 助教授 (30167027)
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| Project Period (FY) |
1992 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥6,600,000 (Direct Cost: ¥6,600,000)
Fiscal Year 1994: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1993: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1992: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Keywords | Quasi-biennial oscillation / Eguatorial waves / Kelvin waves / Rossby-gravity waves / Internal gravity waves / Short-period disturbances / 内部動波 / 赤道成層圏 / 平均東西風 |
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| Research Abstract |
A statistical analysis was carried out of short-period disturbances in the equatorial lower stratosphere, with use of balloon observations at Singapore (lN,104E) for 15 years of 1978 - 1993. It is found that internal waves having a period of about 2 days are dominant independently from the well-known longer-period waves such as Kelvin waves and Rossby-gravity waves. Results of long-term statistics show that these short-period waves are strongly connected with the QBO.
Space-time variations of atmospheric temperature in the equatorial lower stratosphere ax investigated using temperature data derived from UARS-CLAES observations for January 1992 to May 1993. During this period, clear evidence of Kelvin waves is observed for eastward progression of zonal wavenumber 1 temperature anomalies. The Kelvin wave activity is vigorous during the easterly regime, but rapidly decreases in the westerly regime of the QBO.
Response of the atmosphere to transient localized heating in the tropics is studied theoretically and nemerically. The method of separation of variables is used to analyze the linearized primitive equations. Dependence of the wave excitation on several parameters of the heating is clarified. Time-integrations of a full nonlinear model with accurate radiative calculations are also done to investigate the propagation of excited waves in some climatological basic states including two opposite QBO phases.
Laboratory experiment of QBO done by Plumb and McEwan (1978) was double cheked using same size of apparatus. The formation of mean flow and its reverse were confirmed. The period of reverse, however, was very sensitive to the stratification of narrow region at the source of wave, and varied significantly.
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