Assessment of the breakup of the Antarctic polar vortex in two new chemistry-climate models

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Journal of Geophysical Research Atmospheres - 2010 - Hurwitz - Assessment of the breakup of the Antarctic polar vortex in.pdf (1.2 MB)

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https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2009JD012788

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https://doi.org/10.1029/2009JD012788
 http://hdl.handle.net/11603/26736

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https://orcid.org/0000-0002-7928-0775

Date

2010-04-14

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journal articles
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Citation of Original Publication

Hurwitz, M. M., P. A. Newman, F. Li, L. D. Oman, O. Morgenstern, P. Braesicke, and J. A. Pyle (2010), Assessmentof the breakup of the Antarctic polar vortex in two new chemistry‐climate models,J. Geophys. Res.,115, D07105,doi:10.1029/2009JD012788.

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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract

Successful simulation of the breakup of the Antarctic polar vortex depends on the representation of tropospheric stationary waves at Southern Hemisphere middle latitudes. This paper assesses the vortex breakup in two new chemistry-climate models (CCMs). The stratospheric version of the UK Chemistry and Aerosols model is able to reproduce the observed timing of the vortex breakup. Version 2 of the Goddard Earth Observing System (GEOS V2) model is typical of CCMs in that the Antarctic polar vortex breaks up too late; at 10 hPa, the mean transition to easterlies at 60°S is delayed by 12–13 days as compared with the ERA-40 and National Centers for Environmental Prediction reanalyses. The two models' skill in simulating planetary wave driving during the October–November period accounts for differences in their simulation of the vortex breakup, with GEOS V2 unable to simulate the magnitude and tilt of geopotential height anomalies in the troposphere and thus underestimating the wave driving. In the GEOS V2 CCM the delayed breakup of the Antarctic vortex biases polar temperatures and trace gas distributions in the upper stratosphere in November and December.