Evidence of Multistep Vertical Coupling from 10 Years of Lidar Observations at McMurdo, Antarctica

The McMurdo lidar campaign has produced a rich dataset of 10+ years of gravity wave (GW) observations in the upper atmosphere and revealed an extremely dynamic environment in the mesosphere and lower thermosphere (MLT) dominated by strong and persistent GW activity. Analysis of GW properties in the 30 – 50, 50 – 70, and 80 – 105 km ranges shows a clear transition from smaller to larger scale GWs above and below 50 km, as well as a significant reduction in the amount of downward propagating waves above 80 km. These results are consistent with modeling studies of secondary wave generation, indicating this is the predominant source of GWs in the polar MLT. Findings highlight the importance of multistep vertical coupling as a pathway for GWs to transfer energy and momentum from the troposphere to ionospheric heights and significantly influence temperature, wind, constituent, and electron density. Observational studies with long-term datasets such as this are a key step towards developing a better understanding of GWs on a global scale and more accurate modelling tools for the CEDAR community as the lack of realistic representations of GW processes is a key source of inaccuracies in atmospheric and space weather models.