What does the Variability of Earth’s highest clouds tell us?

Polar Mesospheric Clouds form in a unique environment found only in the polar summer. That is, the summer polar mesopause, despite being exposed to the sunlight incessantly, becomes the coldest region on the planet leading to water vapor supersaturation, cultivating an environment that forms and sustains these water ice clouds making them Earth’s highest clouds. PMCs are sensitive to any factors affecting polar mesospheric temperature and water vapor, such as Inter-Hemispheric Coupling (IHC), Solar Proton Events (SPEs), thermal tides, global climate change, etc., making these clouds an excellent tracer of polar atmospheric dynamics and coupling effects. Given PMCs’ sensitivities to a myriad range of dynamic atmospheric processes across both the lower and upper atmosphere, trends in their variability can serve as a canary in the coal mine, warning us of potential long-term changes in regions of the atmosphere and global climate change.
Utilizing a decade of PMC observations from a ground-based Fe Boltzmann lidar at McMurdo and 14 years of CIPS PMC observations onboard NASA’s Aeronomy of Ice in the Mesosphere (AIM) satellite around McMurdo, Antarctica, we unravel the variability of these clouds, exploring the impact of the solar cycle, polar vortex, gravity waves, and planetary waves on the polar summer MLT.