| 27 Nov 2025
Atmospheric vertical structure variations during severe aerosol pollution events based on lidar observations
Abstract. During severe haze events, the boundary layer exhibits a complex vertical structure, while high aerosol loadings hinder high-resolution temperature and humidity measurements. To address this, a Raman-Mie lidar and retrieval algorithms for temperature, humidity, and aerosol optical properties were developed at Xi’an University of Technology, enabling high-resolution profiling of haze vertical structures. A 12-day haze episode was continuously monitored from formation to dissipation, providing detailed spatiotemporal variations of temperature, relative humidity, and aerosols. The boundaries of temperature inversion (TI) and aerosol layers were identified using a threshold method. The results revealed a strong coupling between aerosols and temperature during pollution evolution. Dome and stove effects were observed, with possible coexistence and interaction. Three dome-shaped TIs were identified. The top of a decreasing-type aerosol layer formed a stratified dome structure that constrained vertical diffusion, with the temperature gradient of the elevated TI varying inversely with its depth. Both TI strength and humidity were strongly correlated with surface PM2.5 concentrations. Surface-based TI exhibited a clear diurnal variation, with TI peaks preceding aerosol peaks. The results indicated that strong elevated TI and weak turbulence in the lower layer favored aerosol accumulation. Clouds and virga not only suppressed radiative heating but also enhanced humidity, further driving the rapid increase in surface PM2.5 concentrations. During the dissipation stage, the rapid breakdown of TI and enhanced solar heating were critical for pollutant removal, while efficient horizontal transport facilitated the complete clearance of aerosols within the boundary layer.
This manuscript “Atmospheric vertical structure variations during severe aerosol pollution events based on lidar observations” presents an observation-driven investigation of boundary-layer thermodynamic structure during a severe winter haze episode. This manuscript presents continuous Raman–Mie lidar observations of a severe winter haze episode in Xi’an, focusing on the coupled evolution of aerosol vertical structure, temperature inversions (TIs), humidity, and boundary-layer dynamics. By applying correction algorithms to mitigate elastic scattering cross-talk and geometric overlap effects, the authors retrieve high-resolution thermodynamic profiles under heavy aerosol loading and analyze aerosol–radiation–boundary-layer feedbacks, including the coexistence of dome and stove effects.
The topic is highly relevant to the atmospheric and aerosol science community, and the dataset is valuable and rare, particularly the continuous temperature and humidity profiling during severe haze. The manuscript demonstrates substantial observational effort and methodological development. However, the scientific narrative occasionally moves beyond what can be uniquely inferred from the observations, lacks sufficient uncertainty assessment, and requires clearer separation between observation, inference, and mechanism. Significant revisions are needed before the manuscript can be considered for publication. The dataset is impressive and addresses a significant gap in our understanding of fine-scale thermodynamic evolution during haze development. However, the manuscript’s transition from observation to mechanistic interpretation is sometimes speculative.