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| Titel |
Simulation of the climate impact of Mt. Pinatubo eruption using ECHAM5 – Part 2: Sensitivity to the phase of the QBO and ENSO |
| VerfasserIn |
M. A. Thomas, M. A. Giorgetta, C. Timmreck, H.-F. Graf, G. Stenchikov |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 9 ; Nr. 9, no. 9 (2009-05-11), S.3001-3009 |
| Datensatznummer |
250007268
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| Publikation (Nr.) |
 copernicus.org/acp-9-3001-2009.pdf |
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| Zusammenfassung |
| The sensitivity of the climate impact of Mt. Pinatubo eruption in the tropics
and extratropics to different QBO phases is investigated. Mt. Pinatubo
erupted in June 1991 during the easterly phase of the QBO at 30 hPa and the
phase change to westerly took place in August 1992. Here, the consequences
are analyzed if the QBO phase had been in the opposite phase during the
eruption of Mt. Pinatubo. Hence, in this study, simulations are carried out
using the middle atmosphere configuration of ECHAM5 general circulation model
for two cases – one with the observed QBO phase and the other with the
opposite QBO phase. The response of temperature and geopotential height in
the lower stratosphere is evaluated for the following cases – (1) when only
the effects of the QBO are included and (2) when the effects of aerosols, QBO
and SSTs (combined response) are included. The tropical QBO signature in the
lower stratospheric temperature is well captured in the pure QBO responses
and in the combined (aerosol + ocean + QBO) responses. The response of the
extratropical atmosphere to the QBO during the second winter after the
eruption is captured realistically in the case of the combined forcing
showing a strengthening of the polar vortex when the QBO is in its westerly
phase and a warm, weak polar vortex in the easterly QBO phase. The vortex is
disturbed during the first winter irrespective of the QBO phases in the
combined responses and this may be due to the strong influences of El
Niño during the first winters after eruption. However, the pure
QBO experiments do not realistically reproduce a strengthening of the polar
vortex in the westerly QBO phase, even though below normal temperatures in
the high latitudes are seen in October-November-December months when the opposite QBO phase
is prescribed instead of the December-January-February winter months used here for
averaging. |
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