Evaluating Sources of Gravity Waves in the Upper Atmosphere Using 10 Years of Lidar Observations at McMurdo, Antarctica

Gravity waves (GWs) are a ubiquitous and important source of variability in the upper atmosphere environment. However, much remains unclear regarding how GWs transport energy and momentum from the lower atmosphere to ionospheric heights. The McMurdo lidar campaign has produced a rich dataset of 10+ years of GW observations in the upper atmosphere and revealed an extremely dynamic environment in the mesosphere and lower thermosphere (MLT). Multistep vertical coupling through secondary wave generation has been proposed as the source of persistent and strong GW activity in the MLT above McMurdo, but conclusive observational evidence supporting this hypothesis has not yet been produced. The aim of this work is to investigate the dominant sources of GWs in the upper atmosphere above McMurdo through an analysis of variability in GW spectral properties and background atmospheric conditions from the stratosphere to the thermosphere. The multistep vertical coupling mechanism provides a means by which GWs can propagate high into the thermosphere. By evaluating the role this mechanism plays at McMurdo, this work will generate new insights into the GW processes that act on a global scale. The majority of atmospheric and space weather models lack realistic representations of GW activity and sources, so observational studies such as this are a key step towards developing more accurate modelling tools for the CEDAR community.