The Tibetan Plateau (TP), as a remote and sparsely populated area, is regularly exposed to polluted air masses sourcing from surrounding regions. Atmospheric circulation, as the major driving force generating long-range transport processes of air pollutants, contributes to high-pollution episodes on the TP. Therefore, using reanalysis data from the European Centre for Medium-Range Weather Forecasts for the 2000-2019 period, this paper first classified atmospheric circulation patterns over the study area into nine types (type 1 - type 9). Among them, circulation types 1, 2, 6, and 8 mainly occurred in spring and winter, while circulation types 3, 4, 5, 7, and 9 primarily occurred in summer and autumn. Second, ground-based and satellite remote sensing data were combined to investigate the impact of atmospheric circulation patterns on the properties of aerosols over Central West Asia and their surrounding areas. We detailed how the atmospheric circulation patterns impacted the aerosol optical depth, angstrom ngstro center dot m exponent, and aerosol types at different Aerosol Robotic Network sites in the study area. The results obtained from ground-based data were further verified by those from satellite remote sensing data. Third, backward trajectories and the corresponding potential source contribution function based on the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model were used to explore the impact of atmospheric circulation patterns on regional transport pathways of aerosols. It was found that under circulation types 1, 2, 6, and 8, few HYSPLIT trajectories were sourced from the south direction, while under circulation types 3, 4, 5, 7, and 9, the trajectories originating from the south increased significantly, which could be attributed to the summer monsoon.

Regional atmospheric circulation patterns affect haze pollution and they change in the warming climate. Here, the characteristics of atmospheric circulation anomalies conducive to extreme haze occurrence in China and their historical and future trends are examined based on surface observations, reanalysis data, aerosol source tagging technique, and multimodel intercomparison results. December 2016 and 2017 are identified as the worst months of haze pollution over northern and southern China, featuring weakened and strengthened prevailing winds, respectively. During 1980-2019, the atmospheric pattern similar to December 2016 decreased, while that similar to 2017 increased, suggesting that severe haze formation mechanism in eastern China has been shifting from causes of local accumulation to regional transport processes. In the future, climate change under the sustainable and intermediate development scenarios are the ideal paths to reduce haze in China, while high social vulnerability and radiative forcing would cause a severe damage to the environment.