Anthropogenic aerosol feedbacks intensify air pollution and weather variability over China

Abstract

Aerosols from human activities significantly affect the radiative balance and energy equilibrium of the atmosphere, thereby influencing air pollutant concentrations and meteorological factors. This study examines the Chinese mainland and its surrounding regions in 2014, revealing that aerosols influence meteorological factors and therefore the pollutant concentrations, especially in areas experiencing severe particulate pollution. The aerosol feedback not only increases the annual average concentration of pollutants such as PM_2.5 (0.30 μg m⁻³) and CO (4.04 ppbV), but also reduces the annual average values of meteorological variables such as surface temperature (0.18 K) and wind speed (0.01 m s⁻¹). The magnitude of aerosol feedback on pollutants and meteorological factors depends primarily on the mass concentration of aerosols. During the 2014 Asia-Pacific Economic Cooperation (APEC) Summit in Beijing emission reduction period, the impact of aerosol feedback on pollutants and meteorology was clearly weakened in the key emission reduction areas, reflecting the influence of aerosol feedback. Importantly, the feedback effects of aerosols in heavily polluted areas is up to an order of magnitude greater than in the broader study region, although with large spatial variability. In the heavily polluted areas like Beijing, PM_2.5 concentrations correlate well with the difference of temperature and wind speed between Beijing and its surrounding areas. It is also shown that, in case of heavy pollution, WRF-Chem model predictive capabilities often diminish, presenting underestimation and shortcomings in assessing the impact of aerosols on heavy pollution and regional disparities. This implies that some feedback processes involving anthropogenic aerosols may not be fully represented in the model. In the face of increasingly severe climate change, better understanding of the bidirectional interactions between aerosols and meteorology, along with associated feedback mechanisms, is essential for effectively mitigating air pollution, adapting to climate change, and managing climate impacts. This study highlights the critical role of aerosol feedback in regional pollution and modulating meteorological factors, providing a scientific basis for targeted air quality management and climate mitigation strategies in heavily polluted areas.