Turbulent Coupling and Transport in the Space Transition Region

Turbulence is recognized as coupling the mesosphere-lower thermosphere (MLT) both upward to the upper thermosphere and F-region and downward to the mesosphere and stratosphere. The upward coupling impacts the composition of the thermosphere and satellite drag. The downward coupling impacts the transport of nitric oxides and the ozone layer. However, measurement and characterization of turbulence remains challenging. Significant uncertainties are reported in the estimates of turbulent activity and transport in both observational and modeling studies. In this presentation we present recent measurements of turbulence in the MLT from ground-based lidar (i.e., Andes Lidar Observatory), ground-based radar (i.e., Poker Flat Incoherent Scatter Radar), and in-situ rocket probes (i.e., Mesosphere Lower-Thermosphere Turbulence Experiment). These techniques adopt different approaches to measuring and characterizing turbulence. We consider these observations in the light of recent studies with general circulation models (i.e., HAMMONIA and WACCM). Given that the primary source of turbulence is breaking gravity waves, we consider systematic variations in turbulent activity associated with systematic variations in gravity wave activity. We identify the experimental requirements for future observational studies.