Thermal and dynamical perturbations in the winter polar mesosphere‐lower thermosphere region associated with sudden stratospheric warmings under conditions of low solar activity

Abstract

The upper mesospheric neutral winds and temperatures have been derived from continuous meteor radar (MR) measurements over Sodankyla, Finland, in 2008–2014. Under conditions of low solar activity pronounced sudden mesospheric coolings linked to the major stratospheric warming (SSW) in 2009 and a medium SSW in 2010 are observed while there is no observed thermal signature of the major SSW in 2013 occurred during the solar maximum. Mesosphere‐ionosphere anomalies observed simultaneously by the MR, the Aura satellite, and the rapid‐run ionosonde during a period of major SSW include the following features. The mesospheric temperature minimum occurs 1 day ahead of the stratospheric maximum, and the mesospheric cooling is almost of the same value as the stratospheric warming (~50 K), the former decay faster than the latter. In the course of SSW, a strong mesospheric wind shear of ~70 m/s/km occurs. The wind turns clockwise (anticlockwise) from north‐eastward (south‐eastward) to south‐westward (north‐westward) above (below) 90 km. As the mesospheric temperature reaches its minimum, the gravity waves (GW) in the ionosphere with periods of 10–60 min decay abruptly while the GWs with longer periods are not affected. The effect is explained by selective filtering and/or increased turbulence near the mesopause.

Mesospheric temperature estimation from meteor decay times during Geminids meteor shower

“…This annual variation is indeed typical for high latitudes because of the global atmospheric circulation [e. g., Andrews et al ., ]. Also, noticeable are temperature drops by about 20 K in January 2009 and 2010, which were associated with sudden stratospheric warmings (SSWs) [ Lukianova et al ., ]. Thus, the SGO MR data demonstrate agreement with commonly accepted concepts of mesosphere physics.…”

“…Recently, similar comparison between SGO MR and Aura MLS data was performed for the event of sudden stratospheric warming in January 2009, and reasonable agreement of the temperature variations in both instruments was shown [ Lukianova et al ., ]. As an additional check, we calculated daily averaged temperature from the MR data obtained only for the 02–04 and 12–14 local time intervals to match to the Aura measurements.…”

Thermal and dynamic perturbations in the winter polar upper atmosphere associated with a major sudden stratospheric warming

“…Both instruments have been operating since December 2008. Recently, a technique has been suggested to reveal the statistical characteristics of TIDs from the ionosonde data [Kozlovsky et al, 2013] and the MR measurements has been analysed to infer the signatures associated with a SSW [Lukianova et al, 2015].…”

Variations in Ionospheric Peak Electron Density During Sudden Stratospheric Warmings in the Arctic Region

“…In the mesosphere, air cooling is observed over the warming area in the stratosphere (Labitzke, , ). When studying upper mesospheric neutral winds and temperature over Sodankyla, Lukianova et al () observed pronounced mesospheric cooling, accompanied by a strong mesospheric wind shear of ~70 m/s/km during the 2009 major stratospheric warming. The cooling occurred 1 day earlier than the stratosphere maximum and was just about the same magnitude as the stratospheric warming (~50 K).…”

“…Yiğit and Medvedev () noted a possible role of gravity waves in vertical coupling between the lower and the upper atmospheres during SSW events. However, Lukianova et al (), based on meteor radar measurements, recorded the decay of gravity waves with 10–60‐min periods in the ionosphere over Sodankyla during the 2009 SSW.…”