EOMF-38. A Study of PMC Variability Using 10 years of Lidar and CIPS Observations of PMCs in Antarctica

Polar Mesospheric Clouds (PMCs), the highest occurring clouds on Earth are a unique phenomenon of the mesosphere and lower thermosphere (MLT) region. These water ice particles occur at 85 km altitude during the polar summer serving as important tracers for the mesosphere. Using 10 years of Fe Boltzmann Lidar PMC observations at McMurdo, and 15 years of PMCs observed from CIPS instrument onboard NASA’s AIM satellite, around McMurdo at Antarctica, this study looks at the drivers behind the PMC variability, providing insights on the long-term trends of PMCs in Antarctica. The formation of clouds is mainly governed by the mesospheric temperature, water vapor, with dust particles acting as a nucleation site. This study investigates the impact of dynamic processes such as polar vortex breakup on the PMC brightness variability. Stratospheric wind reversal dates are used as a proxy for the polar vortex break up timing, for when the winter polar mesosphere transitions to summer, causing cold temperatures for PMC formation. Next, the role of radiative forcing from the solar flux in the PMC variability is examined. Previous studies pertaining to the 24th solar cycle show a lack of solar cycle signature in PMCs, this study addresses the question - Could the dynamical forcing of the polar vortex overshadow radiative forcing, causing the solar cycle to take a back seat in driving PMC variability?