ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-9-4775-2009 Satellite observations and modeling of transport in the upper troposphere through the lower mesosphere during the 2006 major stratospheric sudden warming Manney G. L. 1 2 Harwood R. S. 3 MacKenzie I. A. 3 Minschwaner K. 2 Allen D. R. 4 Santee M. L. 1 Walker K. A. 5 6 Hegglin M. I. 5 Lambert A. 1 Pumphrey H. C. 3 Bernath P. F. 6 7 Boone C. D. 6 Schwartz M. J. 1 Livesey N. J. 1 Daffer W. H. 1 Fuller R. A. 1 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA New Mexico Institute of Mining and Technology, Socorro, NM, USA University of Edinburgh, Edinburgh, UK Dordt College, Sioux Center, IA, USA University of Toronto, Toronto, Ontario, Canada University of Waterloo, Waterloo, Ontario, Canada University of York, Heslington, York, UK 20 07 2009 9 14 4775 4795 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.net/9/4775/2009/acp-9-4775-2009.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/9/4775/2009/acp-9-4775-2009.pdf

An unusually strong and prolonged stratospheric sudden warming (SSW) in January 2006 was the first major SSW for which globally distributed long-lived trace gas data are available covering the upper troposphere through the lower mesosphere. We use Aura Microwave Limb Sounder (MLS), Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS) data, the SLIMCAT Chemistry Transport Model (CTM), and assimilated meteorological analyses to provide a comprehensive picture of transport during this event. The upper tropospheric ridge that triggered the SSW was associated with an elevated tropopause and layering in trace gas profiles in conjunction with stratospheric and tropospheric intrusions. Anomalous poleward transport (with corresponding quasi-isentropic troposphere-to-stratosphere exchange at the lowest levels studied) in the region over the ridge extended well into the lower stratosphere. In the middle and upper stratosphere, the breakdown of the polar vortex transport barrier was seen in a signature of rapid, widespread mixing in trace gases, including CO, H<sub>2</sub>O, CH<sub>4</sub> and N<sub>2</sub>O. The vortex broke down slightly later and more slowly in the lower than in the middle stratosphere. In the middle and lower stratosphere, small remnants with trace gas values characteristic of the pre-SSW vortex lingered through the weak and slow recovery of the vortex. The upper stratospheric vortex quickly reformed, and, as enhanced diabatic descent set in, CO descended into this strong vortex, echoing the fall vortex development. Trace gas evolution in the SLIMCAT CTM agrees well with that in the satellite trace gas data from the upper troposphere through the middle stratosphere. In the upper stratosphere and lower mesosphere, the SLIMCAT simulation does not capture the strong descent of mesospheric CO and H<sub>2</sub>O values into the reformed vortex; this poor CTM performance in the upper stratosphere and lower mesosphere results primarily from biases in the diabatic descent in assimilated analyses.

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