The Sensitivity of Polar Mesospheric Clouds to Mesospheric Temperature and Water Vapor

• Published in: Remote Sensing
• Main Authors: Jae N. Lee, Dong L. Wu, Brentha Thurairajah, Yuta Hozumi, Takuo Tsuda
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2024
• Subjects: polar mesospheric clouds; water vapor; temperature; mesosphere; Science; Q; Antarctic; Arctic; Antarc*
• Online Access: https://doi.org/10.3390/rs16091563; https://doaj.org/article/bbaf5c470d0f4a0196927a7b49b1a4f4

Polar mesospheric cloud (PMC) data obtained from the Aeronomy of Ice in the Mesosphere (AIM)/Cloud Imaging and Particle Size (CIPS) experiment and Himawari-8/Advanced Himawari Imager (AHI) observations are analyzed for multi-year climatology and interannual variations. Linkages between PMCs, mesospheric temperature, and water vapor (H 2 O) are further investigated with data from the Microwave Limb Sounder (MLS). Our analysis shows that PMC onset date and occurrence rate are strongly dependent on the atmospheric environment, i.e., the underlying seasonal behavior of temperature and water vapor. Upper-mesospheric dehydration by PMCs is evident in the MLS water vapor observations. The spatial patterns of the depleted water vapor correspond to the PMC occurrence region over the Arctic and Antarctic during the days after the summer solstice. The year-to-year variabilities in PMC occurrence rates and onset dates are highly correlated with mesospheric temperature and H 2 O. They show quasi-quadrennial oscillation (QQO) with 4–5-year periods, particularly in the southern hemisphere (SH). The combined influence of mesospheric cooling and the mesospheric H 2 O increase provides favorable conditions for PMC formation. The global increase in mesospheric H 2 O during the last decade may explain the increased PMC occurrence in the northern hemisphere (NH). Although mesospheric temperature and H 2 O exhibit a strong 11-year variation, little solar cycle signatures are found in the PMC occurrence during 2007–2021.