The existence of an iron layer in the Mesosphere and Lower Thermosphere (MLT) produced by meteoric deposition provides a unique opportunity to study the dynamics of this region of the atmosphere. The McMurdo lidar observational campaign, conducted by the University of Colorado lidar group, has been underway since December 2010. The deployment and operation of an Fe Boltzmann lidar at Arrival Heights observatory (77.8 ºS, 166.7 ºE) has produced multiple years of iron temperature and density measurements.

Recent observations made using the Fe Boltzmann lidar reveal that temperature variations in the Antarctic MLT are driven by seemingly ever present, persistent gravity waves. Waves with periods of ~3 – 10 hours and vertical wavelengths of ~20 – 30 km have been present and dominant in the upper atmosphere temperature perturbations for every lidar run over multiple years of observations. Thus far the extensive calculations of gravity wave characteristics in this region have only been conducted in June along with a few cases in May and July [Chen et al., 2016; Chen and Chu, 2017]. Internal gravity waves play a key role in distributing energy and momentum throughout the atmosphere and so an understanding of any seasonal changes in their properties is necessary to fully understand the dynamics of the MLT region.

In order to characterize seasonal variations of these gravity waves, a two-dimensional fast Fourier transform is used to analyze the period and vertical wavelength spectra as well as potential energy densities of multiple years of iron temperature and density measurements. Iron density measurements will be used to assist the calculations of gravity wave parameters in the summer, fall, and spring seasons whenever Fe temperature measurements do not provide high resolutions due to the high solar background hindering signal to noise ratios. Proposed wave sources and generation mechanisms include secondary wave generation, spontaneous radiation caused by jet stream interactions, and even a resonance oscillation of the Ross Ice Shelf. We hope that this analysis and comparison with seasonal gravity wave trends in the stratosphere provides clues as to dominant wave sources.