A review of the mesosphere inversion layer phenomenon

Abstract

Abstract. An active topic of current research in aeronomy is the study of the dynamics of the mesosphere and lower thermosphere (MLT) from 60 to 130 km, especially in regard to the influences that govern variability. The physical processes of this region are diverse and complex with strong coupling between the MLT and the adjacent atmospheric regions brought about largely by the propagation and dissipation of atmospheric gravity waves (GWs) from sources above and below. The measurements of MLT winds and temperatures required for such studies represent daunting technical challenges. At low and midlatitudes the mesosphere inversion layer (MIL) phenomenon, a -• 10 km wide region of enhanced temperatures (AT-• 15-50K), is observed with great regularity in both the upper mesosphere (60-70 km) and the mesopause (90-100 km). Observations are largely based upon Rayleigh and Na temperature lidar systems but coherent radar observations have shown that the MIL phenomenon is linked to layers of turbulence occurring in both the topside and the bottomside regions. GW activity is believed to play an important role in the development of a linkage between the MIL and the tidal structure through GW coupling that results in an amplification of the tidal thermal structure. This linkage is readily evident for the upper MIL but is seen only occasionally for the lower MIL. Further study of MIL properties should emphasize continual 24 hour temperature observations, especially for the lower MIL region, to confirm the linkage of the development of the MIL to the MLT tidal structure.

Simultaneous observations of a Mesospheric Inversion Layer and turbulence during the ECOMA-2010 rocket campaign

“…The first was initially proposed by Whiteway et al (1995) and basically explains the formation of MIL by turbulent heating. The second goes back to Dao et al (1995) and was summarized e.g., by Meriwether and Gardner (2000) and explains the formation of a MIL via the interaction of tides with gravity waves. Both these scenarios are discussed in detail e.g., in the review article by Meriwether and Gerrard (2004).…”

“…One of the arguments against turbulence heating as an important physical process (e.g., Meriwether and Gardner, 2000) in development of the inversion layers was based on the mean dissipation values published by Lübken (1997) and Lübken et al (2002). However, there are two points that have to be taken into account.…”

Properties of the Long-Term Oscillations in the Middle Atmosphere Based on Observations from TIMED/SABER Instrument and FPI over Kelan

“…Studies have revealed that the MIL can be divided into two sub-layers: the lower and the upper MILs at approximately 75 and 90 km, respectively (e.g., [23,46]). The following discussion is concerned with the lower MIL.…”

Observations and Modeling of the Upper Mesosphere: Mesopause Characteristics, Inversion Layers, and Bores

“…One particularly interesting feature is the temperature inversion layer (TIL). Mesospheric TILs, which have been the subject of great research interest in recent years [e.g., Leblanc and Hauchecorne, 1997;Gardner, 2000, Meriwether andGerrard, 2004;Sassi et al, 2002, Huang et al, 1998, appear with regularity in the SABER data. Each of the temperature profiles shown in Figure 5 in the preceding section has more than one TIL.…”