The evolution of the stratopause during the 2006 major warming: Satellite data and assimilated meteorological analyses

Abstract

[1] Microwave Limb Sounder and Sounding of the Atmosphere with Broadband Emission Radiometry data provide the first opportunity to characterize the four-dimensional stratopause evolution throughout the life-cycle of a major stratospheric sudden warming (SSW). The polar stratopause, usually higher than that at midlatitudes, dropped by $30 km and warmed during development of a major ''wave 1'' SSW in January 2006, with accompanying mesospheric cooling. When the polar vortex broke down, the stratopause cooled and became ill-defined, with a nearly isothermal stratosphere. After the polar vortex started to recover in the upper stratosphere/lower mesosphere (USLM), a cool stratopause reformed above 75 km, then dropped and warmed; both the mesosphere above and the stratosphere below cooled at this time. The polar stratopause remained separated from that at midlatitudes across the core of the polar night jet. In the early stages of the SSW, the strongly tilted (westward with increasing altitude) polar vortex extended into the mesosphere, and enclosed a secondary temperature maximum extending westward and slightly equatorward from the highest altitude part of the polar stratopause over the cool stratopause near the vortex edge. The temperature evolution in the USLM resulted in strongly enhanced radiative cooling in the mesosphere during the recovery from the SSW, but significantly reduced radiative cooling in the upper stratosphere. Assimilated meteorological analyses from the European Centre for Medium-Range weather Forecasts (ECMWF) and Goddard Earth Observing System Version 5.0.1 (GEOS-5), which are not constrained by data at polar stratopause altitudes and have model tops near 80 km, could not capture the secondary temperature maximum or the high stratopause after the SSW; they also misrepresent polar temperature structure during and after the stratopause breakdown, leading to large biases in their radiative heating rates. ECMWF analyses represent the stratospheric temperature structure more accurately, suggesting a better representation of vertical motion; GEOS-5 analyses more faithfully describe stratopause level wind and wave amplitudes. The high-quality satellite temperature data used here provide the first daily, global, multiannual data sets suitable for assessing and, eventually, improving representation of the USLM in models and assimilation systems.

Simulation study for measurement of horizontal wind profiles in the polar stratosphere and mesosphere using ground-based observations of ozone and carbon monoxide lines in the 230–250 GHz region

“…Superimposed on the mean flow are atmospheric tides and vertically propagating waves that influence the planetary-scale circulation of the stratosphere, drive mesospheric circulation, and drive chemical transport and temperature gradients through pole-pole meridional circulation, turbulent mixing, and diffusion (Brasseur and Solomon, 2005;Holton, 2004). These impact on the stability of the northern and southern hemisphere polar vortices where abrupt changes or even reversals of strong zonal winds during sudden stratospheric warming (SSW) events lead to strong dynamical and chemical coupling between the lower and upper atmosphere (Manney et al, 2008). New wind observing techniques for the polar regions are essential to better understand and parameterise these processes in circulation models for climate studies and numerical weather prediction.…”

A Match-based approach to the estimation of polar stratospheric ozone loss using Aura Microwave Limb Sounder observations

“…Sinnhuber et al (2011) The 2005/06, 2008/09, 2011/12, and 2012/13 Arctic winters have the smallest losses, in many cases indistinguishable from zero when possible transport errors are factored in. These winters featured sudden stratospheric warmings (SSWs) that resulted in early chlorine deactivation (e.g., Manney et al, 2008Manney et al, , 2009Coy and Pawson, 2015; , 2015). During these winters there were periods when the circulation was sufficiently disturbed that no meaningful polar vortex could be defined (none of the vortex fragments that remained encompassed more than 1 % of a hemisphere).…”

Satellite observations of middle atmosphere gravity wave absolute momentum flux and of its vertical gradient during recent stratospheric warmings

“…Then, after a short period of nearly isothermal conditions in the whole middle atmosphere, a new stratopause forms at altitudes around 75 km, propagates gradually downward with time, and reaches its nominal (climatological) altitude of around 50 km after 1-2 months. Similarly, an eastward-directed polar jet re-establishes at elevated altitudes and propagates downward together with the elevated stratopause (e.g., Manney et al, 2008Manney et al, , 2009aOrsolini et al, 2010).…”