1991 Fiscal Year Final Research Report Summary
| Project/Area Number |
02044078
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | Kyoto University |
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Principal Investigator |
HIROTA Isamu Faculty of Science, Kyoto University, 理学部, 教授 (70025485)
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| Co-Investigator(Kenkyū-buntansha) |
RANDEL William J. National Center for Atmospheric Research, 大気化学部・大気モデリング課(米国), 研究員
BOVILLE Byron National Center for Atmospheric Research, 気候および全球力学部・気候モデル課(米国), 副課長
BRASSEUR Guy National Center for Atmospheric Research, 大気化学部・大気モデリング課(米国), 課長
GILLE John C. National Center for Atmospheric Research, 大気化学部・全球・遠隔観測課(米国), 課長
KANZAWA Hiroshi National Institute of Polar Research, 資料系, 助手 (20150047)
SHIOTANI Masato Faculty of Science, Kyoto University, 理学部, 助手 (50192604)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Stratospheric ozone / SBUV data / TOMS data / Equatorial Kelvin wave / Semiannual oscillation / Quasi-biennial oscillation / ENSO cycle |
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| Research Abstract |
Long-term variations in stratospheric ozone are investigated by using the ozone mixing ratio data from the solar backscatter ultraviolet (SBUV) and the total column ozone data from the total ozone mapping spectrometer (TOMS) on board the Nimbus 7 satellite.
From a simple photochemical consideration, it is expected that ozone variations in the upper stratosphere are associated with temperature disturbances. Using the SBUV data, clear evidence is presented for the appearance of equatorially trapped "ozone Kelvin waves" above the 10 mb level having a zonal wavenumber one component and an eastward migration period of about 7 days. Statistical results for the SBUV ozone data over the 8 years shows how Kelvin wave amplitudes are closely related to the semiannual oscillation of the zonal mean wind around the stratopause level. Further discussions are made on the effect of the quasi-biennial oscillation (QBO) of the tropical lower stratosphere on the vertical propagation of fast Kelvin waves, which results in the QBO modulation of the mean field around the stratopause level.
Equatorial total ozone variations are described, using 11 years of the TOMS data. Over the equator, an annual cycle in total ozone is conspicuous. The longitudinal structure shows a zonal wavenumber one pattern with minimum values in the western Pacific, indicating a close relationship to vigorous convective activity there. By removing the climatological annual cycle from the original data, there appears the QBO in total ozone. This variation is strongly coupled with the equatorial zonal-wind QBO. Moreover, subtracting zonal mean values from the anomaly data, we see an east-west seesaw variation with a nodal longitude around the date line. This east-west variation, having a characteristic time-scale of about four years, is clearly related to the El Nino and the Southern Oscillation (ENSO) cycle, which involves variations in convective cloud activity.
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