ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-11-22113-2011 The Arctic vortex in March 2011: a dynamical perspective Hurwitz M. M. 1 2 Newman P. A. 2 Garfinkel C. I. 3 Goddard Earth Sciences Technology and Research (GESTAR), Morgan State University, Baltimore, MD, USA NASA Goddard Space Flight Center, Greenbelt, MD, USA Johns Hopkins University, Baltimore, MD, USA 05 08 2011 11 8 22113 22127 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys-discuss.net/11/22113/2011/acpd-11-22113-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/11/22113/2011/acpd-11-22113-2011.pdf

Despite the record ozone loss observed in March 2011, dynamical conditions in the Arctic stratosphere were unusual but not unprecedented. Weak planetary wave driving in February preceded cold anomalies in the polar lower stratosphere in March and a relatively late breakup of the Arctic vortex in April. La Niña conditions and the westerly phase of the quasi-biennial oscillation (QBO) were observed in March 2011. Though these conditions are generally associated with a stronger vortex in mid-winter, the respective cold anomalies do not persist through March. Therefore, the La Niña and QBO-westerly conditions cannot explain the observed cold anomalies in March 2011. In contrast, positive sea surface temperature anomalies in the North Pacific may have contributed to the unusually weak tropospheric wave driving and strong Arctic vortex in late winter 2011.

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