Modes of variability of the vertical temperature profile of the middle atmosphere at mid-latitude: Similarities with solar forcing

A long and continuous temperature data set from ground to mesopause was obtained in merging lidar and radiosonde data at mid-latitude over south of France (44°N). The analyses using Empirical Orthogonal Functions has been applied on vertical temperature profiles to investigate the variability differently than it has been done in previous investigations. This study reveals as the first mode in winter, a strong anti-correlation between upper stratosphere and mesosphere that is most probably link with planetary waves propagation and associated stratospheric warmings. While in summer the variability is located in the mesosphere and associated with mesospheric inversions that are probably generated by gravity waves breaking. This study shows that even if the daily temperature variability appears to be complex, a large part (30%) can be modeled, each season, using the first EOF. These vertical patterns exhibit some similarities with solar-atmospheric responses, suggesting a potential feedback of the dynamic. This is already observed for winter response, but during summer the contribution of gravity waves on the mesospheric solar response suggests future investigations to explore the role of this potential mechanism in solar-atmospheric connections.

► Temperature variability in the mid-latitude has been analyzed using EOF analyses.
► During winter an anti-correlation between upper stratosphere and mesosphere is observed.
► During summer variability is located in the mesosphere and is due to mesospheric inversions.
► The main modes of the variability are similar to the solar responses.
► During summer the link between mesospheric inversions and solar activity should be investigated.