Exploration of stratopause and tropopause evolution in polar winter in satellite data and meteorological analyses

Until the past several years, daily global or hemispheric temperature datasets extending through the mesosphere were largely unavailable. With the launch of the Sounding of the Atmosphere with Broadband Emission Radiometry (SABER) instrument in 2002 and the Aura Microwave Limb Sounder (MLS) in 2004, we now have a wealth of such data. In addition, the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS) has been recording daily temperature profiles at high latitudes in the polar winter of both hemispheres since 2004. Some data centers, particularly the European Center for Medium-Range Weather Forecasting (ECMWF) and NASA's Global Modelling and Assimilation Office (GMAO) are now providing assimilated meteorological analyses at levels into the mesosphere; however, above the upper stratosphere, there are no direct data constraints, so the fields depend strongly on the dynamics and parameterizations in the underlying general circulation models, and there have heretofore been few data with which to compare them. We use MLS, SABER, ACE-FTS, as well as ground-based data, to detail the evolution of the stratopause during recent polar winters, and to assess the skill of the analyses in capturing the observed behavior. The stratopause evolution is also viewed in the context of the underlying tropopause evolution and the phenomena that connect them. We show examples of stratopause/tropopause evolution during stratospheric sudden warmings, and examine interannual and interhemispheric variability.