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Future changes in the Brewer-Dobson circulation under different greenhouse gas concentrations in WACCM4

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Palmeiro Nuñez, Froila María and Calvo Fernández, Natalia (2014) Future changes in the Brewer-Dobson circulation under different greenhouse gas concentrations in WACCM4. Journal of the atmospheric sciences, 71 (8). pp. 2962-2975. ISSN 0022-4928

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Official URL: http://dx.doi.org/ 10.1175/JAS-D-13-0289.1


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Abstract

The climatology and future changes of the Brewer–Dobson circulation (BDC) in three climate change scenarios are studied using the latest version of the Whole Atmosphere Community Climate Model (WACCM4), which is fully coupled to an ocean model. The results show an acceleration in both the shallow and deep branches of circulation in response to increasing greenhouse gases (GHGs) together with an upward displacement of the tropical upwelling in the deep branch near the stratopause. The downward control principle reveals that different waves are involved in forcing the acceleration of the upper and lower branches. Climatological-mean tropical upwelling in both the lower and upper stratosphere is dominated by explicitly resolved, planetary-scale waves. Trends in the tropical upwelling in the lower stratosphere are mainly attributed to explicitly resolved, planetary-scale waves. However, in the upper stratosphere, despite the fact that resolved waves control the forcing of the climatological upwelling, their contribution to the long-term trend diminishes with increasing GHGs, while the role of gravity waves associated with fronts increases and becomes dominant in the model scenario with the largest GHG increases. The intensification and upward displacement of the subtropical tropospheric jets due to climate change leads to filtering of the westerly part of the frontal gravity wave spectrum, leaving the easterly components to reach the upper stratosphere and force the changes in the circulation there.


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© 2014 American Meteorological Society.
The authors are grateful to Jadwiga H. Richter for the helpful discussion and comments on gravity waves. F. M. Palmeiro and N. Calvo were supported by the Spanish Ministry of Economy and Competitiveness trough project CGL12012-34221, ‘‘Mechanisms and Variability of the Troposphere-Stratosphere Coupling.’’ This work was also partially supported by the European Project 603557 STRATOCLIM under program FP7-ENV-2013-two-stage. The Community Earth System Model (CESM) is supported by NSF and the Office of Science of the U.S. Department of Energy. Computing resources were provided by NCAR’s Climate Simulation Laboratory, sponsored by NSF and other agencies. This research was enabled by the computational and storage resources of NCAR’s Computational and Information Systems Laboratory (CISL).

Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:29291
Deposited On:26 Mar 2015 10:09
Last Modified:10 Dec 2018 15:05

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