Mesospheric Irregularities: Insights into Upper Atmospheric Variability

The mesosphere is a highly dynamic region of the Earth’s atmosphere characterized by complex thermal, dynamical, chemical and electromagnetic processes. However, mesospheric irregularities remain poorly understood due to their diverse driving mechanisms, wide spatial and temporal scales, and the challenges of direct observation. This article aims to systematically examine the major types of mesospheric irregularities, their underlying physical mechanisms, controlling factors, spatial and temporal characteristics, and approaches used for their observation and modelling. It also evaluates the application of lidar, radar, airglow imaging, satellite observations and rocket-borne measurements for characterizing mesospheric variability, together with numerical models used to simulate mesospheric dynamics and chemistry. Furthermore, the article identifies major limitations in present observational and modelling approaches and highlights emerging opportunities through advanced instrumentation, integrated observation networks and artificial intelligence-based analysis.