COVID‐19 Pandemic Reveals Distinct Impact of Aerosols on Surface Solar Radiation in China

• Published in: Geophysical research letters 2023-03, Vol.50 (5), p.n/a
• Main Authors: Yang, Xin, Li, Zhigang, Yao, Zhanyu, Tang, Hong, Yang, Shili, Chen, Lu
• Format: Article
• Language: English
• Subjects: Aerosol effects; Aerosol optical properties; Aerosols; Air pollution; Atmospheric particulates; Carbon; COVID-19; Diffuse radiation; Optical properties; Outdoor air quality; Pandemics; Particulate matter; Radiation; Solar radiation; Sun; Vertical distribution
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL101353

With the abrupt and significant drop of PM2.5 concentrations during the lockdown in 2020, hourly direct radiation (Rdir) at surface substantially increased in East China, such as Zhengzhou, Wuhan and Baoshan, with the maximum enhancement of 86% at Wuhan. Most of these stations had decreased diffuse radiation (Rdif) except Zhengzhou. Zhengzhou had both enhanced Rdir and Rdif, as well as reduced but still high PM2.5 concentrations, indicating atmospheric particles were more scattering in this region. At Beijing and Harbin in North and Northeast China, intensification of aerosol pollution led to hourly Rdir (Rdif) falling (rising) up to −28% (59%) and −23% (40%), respectively. By contrast, surface solar radiation (SSR) in West China was also greatly influenced by the elevated dust/smoke layers, revealed by aerosol layer vertical distribution and the reduction of SSR and PM2.5 concentrations. This study highlighted the importance of aerosol optical properties and vertical structures in aerosol–radiation interactions. Plain Language Summary Atmospheric particulate matters block sunlight and reduce the amount of solar radiation reaching the ground. The emission reduction during the COVID‐19 Atmospheric particulate matters block sunlight and reduce the amount of solar radiation reaching the ground. The emission reduction during the COVID‐19 lockdown reduced fine particles (PM2.5) concentrations and resulted in substantial rise of direct radiation and drop of diffuse radiation at most stations in East China, with Wuhan having the maximum enhancement in direct radiation of 86%. The unusual increase of PM2.5 concentrations during the control period in North and Northeast China also correspondingly declined (enhanced) the observed direct (diffuse) radiation at surface. Actually, surface solar radiation is affected not only by particles near the ground, but also by aerosols at high levels. For example, the elevated layer of smoke/dust weakened the direct radiation at Urumqi, Yuzhong, Lhasa and Kunming in West China. In addition, the absorbing/scattering property of ambient aerosols also played a role in the aerosol‐radiation interactions, suggested by the unique increase in both direct and diffuse radiation, as well as reduced but still high PM2.5 concentrations at Zhengzhou. This study provided observational evidences and quantitative ranges of aerosol‐radiation interactions in the COVID‐19 lockdown across China. Key Points Variations of surface solar radiation in Ea