Investigation of a Polar Mesospheric Cloud Front in the Southern Hemisphere: Influence of Temperature Inversion Layers and Gravity Waves

Polar Mesospheric Clouds (PMCs) provide valuable insights into mesospheric dynamics. PMC observations from the Cloud Imaging and Particle Size (CIPS) instrument aboard the Aeronomy of Ice in the Mesosphere (AIM) satellite indicate complex structures, including the PMC front structure. A potential front is confirmed as an actual front only if the CIPS scan exhibits a sharp boundary between the cloudy and mostly clear regions, and if the cloud albedo along the boundary is significantly higher than the adjacent cloudy region. In this study, we conduct a case study of a Southern Hemisphere PMC front structure, utilizing CIPS/AIM observations. To investigate the mesospheric environment of the front, we utilize near-coincident temperature observations from the Sounding of the Atmosphere using the Broadband Emission Radiometry (SABER) instrument. Preliminary analysis suggests that a temperature inversion layer may be responsible for the formation of this front, in agreement with previously published results. To explore the role of gravity waves (GWs) in front formation, we first identify GW sources from zonal winds and geopotential height using Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2) data at the 450 hPa level, spanning 40°S to 90°S, at the UT closest to the front location. To further investigate GW propagation and energy transfer, we conduct GROGRAT ray-tracing simulations for five horizontal wavelengths (100, 200, 500, 800, and 1000 km) and three phase speeds (0, 20, and 40 m/s). These simulations allow us to trace wave trajectories from potential wave sources in the troposphere to the approximate front location in the mesosphere.