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          Institute: MPI für Meteorologie     Collection: Atmosphere in the Earth System     Display Documents

ID: 360752.0, MPI für Meteorologie / Atmosphere in the Earth System
Simulation of the climate impact of Mt. Pinatubo eruption using ECHAM5 – Part 2: Sensitivity to the phase of the QBO
Authors:Thomas, M. A.; Giorgetta, M. A.; Timmreck, C.; Graf, H.-F.; Stenchikov, G.
Date of Publication (YYYY-MM-DD):2009
Title of Journal:Atmospheric Chemistry and Physics
Journal Abbrev.:Atmos. Chem. Phys. Disc.
Start Page:3001
End Page:3009
Review Status:Peer-review
Audience:Not Specified
Abstract / Description: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 Nino 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 oppositeQBO phase is prescribed instead of the December-January-February wintermonths used here for averaging. [References: 37]
External Publication Status:published
Document Type:Article
Communicated by:Carola Kauhs
Affiliations:MPI für Meteorologie/Atmosphere in the Earth System
MPI für Meteorologie/IMPRS Earth System Modelling
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