Effects of emission reductions on major anthropogenic aerosol-radiation-cloud interactions in East Asia in winter during 2007–2020.

East Asia (EA) has always been a highly concern region for human-induced climate change. In this study, a well-developed regional model RegCM4 is employed to investigate the influences of major anthropogenic aerosol (MAA, including sulfate and primary carbonaceous aerosols) variations from 2007 to 2020 on East Asian climates in winter. Results indicate that high MAA loadings in EA in winter mainly appear in Central to Eastern China. In most area of Asia (5°-55°N, 70°-140°E), the multi-year (2007–2020) mean instantaneous direct and total effective radiative forcing (IDRF and ERF) induced by MAAs are −4.22 and −3.90 W·m−2 at the surface in winter, which are 2.29 and 1.96 times of those at the tropopause. In polluted area from southwest to center China (SWCC, 27–33°N, 102–115°E), these forcings are much stronger, which causes a dimmer, cooler and drier surface and further stabilizes the lower atmosphere. The multi-year mean sunshine duration, surface air temperature, precipitation, and boundary layer thickness are changed by −20.32 min·d−1, −0.33 K, −0.08 mm·d−1, and −12.51 m, respectively in SWCC in winter. Both the aerosol surface IDRF and ERF are weakened by above 30% in SWCC in winter since the Action Plan for Air Pollution Prevention and Control was carried out, which results in less surface dimming and cooling by 9.4 min·d−1 and 0.23 K, respectively. During the most outbreak period in COVID-19 epidemic, the aerosol surface IDRF is weakened by approximately 46.87% compared to that before 2013 in SWCC, which may offset the aerosol cooling effect by 0.28 K. • Effects of emission reductions on the ARi and ACi are investigated in East Asia in winter. • ARi and ACi in East Asia in winter likely cause a cooler and drier surface, and a more stable PBL. • The aerosol cooling effect in East Asia in winter is weakened since APPCAP/COVID-19. [ABSTRACT FROM AUTHOR]