Inverse effects of aerosol radiative forcing on heavy PM 2.5 pollution of local accumulation and regional transport over Central China

• Published in: The Science of the total environment Vol. 917; p. 170319
• Main Authors: Sun, Xiaoyun, Zhao, Tianliang, Hu, Jun, Bai, Yongqing, Meng, Lu, Yang, Qingjian, Zhou, Yue, Fu, Weikang
• Format: Journal Article
• Language: English
• Published: Netherlands 24.01.2024
• Subjects: Atmospheric boundary layer; Regional PM(2.5) transport; Aerosol radiative forcing; WRF-Chem
• ISSN: 1879-1026

Regional transport of air pollutants is a crucial factor influencing atmospheric environment, and aerosol radiative forcing (ARF) feedback to atmospheric boundary layer (ABL) structure and ambient air pollution is yet to be comprehensively understood over the receptor region of regional transport. By simulating meteorology and air pollutants during a heavy PM pollution event with WRF-Chem model, we quantitatively investigated the ARF and ABL interaction for PM pollution over the Twain-Hu Basin (THB), a key receptor region of regional transport over central China. Driven by northerly winds, PM was transported from upstream north China to downstream THB accompanied by high PM levels in the free troposphere. The ARF exacerbated local PM accumulation by up to 20 μg m and inhibited the impact of regional transport on PM levels in the ABL with reducing near-surface PM concentrations of 5 μg m over the THB. The ARF-intensified air temperature inversion at the top of ABL was unfavorable for the transported air pollutants crossing the ABL top to the near-surface layer, thus weakening the impact of regional PM transport on air quality in the receptor region. Meanwhile, the ARF of transported PM induced updrafts in the free troposphere, promoting vertical mixing of air pollutants with positive feedback on increasing secondary PM concentrations in the free troposphere. The ARF induced more and less secondary PM formations respectively in the free troposphere and the near-surface layer during the regional transport period of air pollution. These results enhance our comprehension of aerosol-meteorology feedback in regional changes of atmospheric environment with inverse effects of ARF on PM pollution of local accumulation and regional transport.