MLT cooling during stratospheric warming events

Abstract

MLT (Mesosphere and Lower Thermosphere) airglow emission rates and temperatures have been monitored with a Spectral Airglow Temperature Imager (SATI), operated at Resolute Bay (74.68°N, 94.90°W). The 2001/2002 winter season data exhibits a major cooling event for both the O2 and OH emissions near the end of December, a mild event in mid February and a final cooling in early March. These temperature perturbations are compared with the UKMO stratospheric assimilated data for the Resolute Bay location and for zonally averaged data at 75°N, at two pressure levels, 3.16 hPa and 0.316 hPa. For the major event the 3.16 hPa zonally averaged temperature coincides in time with the MLT cooling. The O2 temperatures increase slightly, prior to the stratospheric warming, but after onset both emissions exhibit cooling; this is consistent with the TIME‐GCM/CCM3 predictions for the meridional circulation at high latitudes.

Dynamical coupling of the stratosphere and mesosphere in the 2002 Southern Hemisphere major stratospheric sudden warming

“…[2] The mesospheric temperature and wind at high winter latitudes can change significantly during stratospheric sudden warming (SSW) events [e.g., Walterscheid et al, 2000;Liu and Roble, 2002;Cho et al, 2004], characterized by mesospheric cooling, deceleration or reversal of the mesospheric zonal wind, and change of the residual circulation. Mesospheric cooling [Hernandez, 2003;T.…”

Extracting gravity wave parameters during the September 2002 Southern Hemisphere major sudden stratospheric warming using a SANAE imaging riometer

“…This was primarily due to the existence of higher temperatures than normal, and the disturbance in the mean circulation. This disturbance of the mean circulation and temperature was also detected in the MLT heights (Cho and Shepherd, 2004;Mbatha et al, 2010).…”

“…More details of the 2002 major stratospheric warming can be found in studies by Baldwin et al (2003), Dowdy et al (2004), Mbatha et al (2010) and others. The mean circulation in the stratosphere was characterized by a series of planetary wave events in the 2002 winter that weakened the polar vortex and triggered the SSW in late September (Baldwin et al, 2003;Dowdy et al, 2004;Cho and Shepherd, 2004;Bencherif et al, 2007;Mbatha et al, 2010). A quasi-10-day wave of wavenumber s = 1 travelling in an eastward direction was identified as responsible for triggering the occurrence of the 2002 major SSW (Dowdy et al, 2004).…”

“…This process also leads to mesospheric cooling (e.g. Cho and Shepherd, 2004;Mbatha et al, 2010;Yamashita et al, 2010). A study by Murphy et al (2007) GWs are generated in the troposphere due to a variety of meteorological and orographic situations.…”

Planetary waves in the upper stratosphere and lower mesosphere during 2009 Arctic major stratospheric warming

“…The key mechanism behind the sudden stratospheric warming (SSW), initially proposed by Matsuno (1971) and now widely accepted, relates to the growth of upward propagating transient planetary waves (PWs) and their non-linear interaction with the zonal mean flow. Later, SSWs are reasonably well characterized from observational data sets (Labitzke and Naujokat, 2000;Hoffmann et al, 2002Hoffmann et al, , 2007Venkat Ratnam et al, 2004;Cho et al, 2004;Pancheva et al, 2008) and also through modeling (Newman and Nash, 2004;Manney et al, 2008b).…”