Satellite observations and modeling of transport in the upper troposphere through the lower mesosphere during the 2006 major stratospheric sudden warming 1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
2New Mexico Institute of Mining and Technology, Socorro, NM, USA
3University of Edinburgh, Edinburgh, UK
4Dordt College, Sioux Center, IA, USA
5University of Toronto, Toronto, Ontario, Canada
6University of Waterloo, Waterloo, Ontario, Canada
7University of York, Heslington, York, UK
Received: 28 Feb 2009 – Published in Atmos. Chem. Phys. Discuss.: 16 Apr 2009Abstract. 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, H2O, CH4 and N2O.
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
H2O 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.
Revised: 29 Jun 2009 – Accepted: 08 Jul 2009 – Published: 20 Jul 2009
Citation: Manney, G. L., Harwood, R. S., MacKenzie, I. A., Minschwaner, K., Allen, D. R., Santee, M. L., Walker, K. A., Hegglin, M. I., Lambert, A., Pumphrey, H. C., Bernath, P. F., Boone, C. D., Schwartz, M. J., Livesey, N. J., Daffer, W. H., and Fuller, R. A.: Satellite observations and modeling of transport in the upper troposphere through the lower mesosphere during the 2006 major stratospheric sudden warming, Atmos. Chem. Phys., 9, 4775-4795, doi:10.5194/acp-9-4775-2009, 2009.