A Study of Polar Mesospheric Cloud Front Structures

The polar summer mesosphere provides rich visual clues to the dynamic processes that control this region in the form of Polar Mesospheric Clouds (PMCs). PMCs typically occur in the high-latitude (>60°N) summer mesosphere at the edge of space (~82-86 km). PMCs exhibit complex spatial structures (veils, bands, vortex, voids etc.) including the presence of mesospheric fronts. A ‘front’ like structure in PMCs generally appears as a solitary wave or a sharp step-like boundary that separates a mesospheric cloud and no-cloud regions. We use the extensive database (15 seasons) of PMC images from the CIPS/AIM instrument to study the longitudinal variability in mesospheric fronts. Near-coincident temperature observations from the SABER/TIMED instrument (when available) indicate a 76% presence of Mesospheric Inversion Layers (MILs) in the vicinity of the fronts. We hypothesize that MILs and instability caused by GWs may support the formation of PMC fronts.