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| Titel |
Long-term variations and trends in the simulation of the middle atmosphere 1980-2004 by the chemistry-climate model of the Meteorological Research Institute |
| VerfasserIn |
K. Shibata, M. Deushi |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 26, no. 5 ; Nr. 26, no. 5 (2008-05-28), S.1299-1326 |
| Datensatznummer |
250016104
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| Publikation (Nr.) |
 copernicus.org/angeo-26-1299-2008.pdf |
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| Zusammenfassung |
| A middle-atmosphere simulation of the past 25 years (from 1980 to 2004) has
been performed with a chemistry-climate model (CCM) of the Meteorological
Research Institute (MRI) under observed forcings of sea-surface temperature,
greenhouse gases, halogens, volcanic aerosols, and solar irradiance
variations. The dynamics module of MRI-CCM is a spectral global model
truncated triangularly at a maximum wavenumber of 42 with 68 layers
extending from the surface to 0.01 hPa (about 80 km), wherein the vertical
spacing is 500 m from 100 to 10 hPa. The chemistry-transport module treats 51
species with 124 reactions including heterogeneous reactions. Transport of
chemical species is based on a hybrid semi-Lagrangian scheme, which is a
flux form in the vertical direction and an ordinary semi-Lagrangian form in
the horizontal direction. The MRI-CCM used in this study reproduced a
quasi-biennial oscillation (QBO) of about a 20-month period for wind and
ozone in the equatorial stratosphere. Multiple linear regression analysis
with time lags for volcanic aerosols was performed on the zonal-mean
quantities of the simulated result to separate the trend, the QBO, the El
Chichón and Mount Pinatubo, the 11-year solar cycle, and the El
Niño/Southern Oscillation (ENSO) signals. It is found that MRI-CCM can
more or less realistically reproduce observed trends of annual mean
temperature and ozone, and those of total ozone in each month. MRI-CCM also
reproduced the vertical multi-cell structures of tropical temperature,
zonal-wind, and ozone associated with the QBO, and the mid-latitude total
ozone QBO in each winter hemisphere. Solar irradiance variations of the
11-year cycle were found to affect radiation alone (not photodissociation)
because of an error in making the photolysis lookup table. Nevertheless,
though the heights of the maximum temperature (ozone) in the tropics are
much higher (lower) than observations, MRI-CCM could reproduce the second
maxima of temperature and ozone in the lower stratosphere, demonstrating
that the dynamic effect outweighs the photochemical effect there. The ENSO
signals of annual mean temperature, zonal wind, and ozone are generally
reproduced in the troposphere and below the middle stratosphere. The
volcanic signals of temperature increase and ozone decrease are much
overestimated for both El Chichón and Mount Pinatubo. |
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