Tao, MH; Wang, LL; Chen, LF; Wang, ZF; Tao, JH (2020). Reversal of Aerosol Properties in Eastern China with Rapid Decline of Anthropogenic Emissions. REMOTE SENSING, 12(3), 523.

The clean air actions of the Chinese government since 2013 have led to rapid reduction in anthropogenic emissions during the last five years. In this study, we present a regional-scale insight into the transition of aerosol properties during this special period based on integrated Moderate Resolution Imaging Spectroradiometer (MODIS), Multi-angle Imaging Spectroradiometer (MISR), and ground-based AERONET (AErosol RObotic NETwork) observations. As a response, aerosols in eastern China have exhibited notable reversal in both the amount and optical properties. Regional haze pollution with Aerosol Optical Depth (AOD) > 1.0 in northern China declined from more than 80 days per year to less than 30 days. While fine-mode particles exhibited a continuous decrease by 30-40% during the time period of 2013-2018, the levels of coarse aerosols had no regular variations. MISR fraction AOD of different size modes shows that there has been an obvious overall decline in coarse particles over eastern China, but natural sources such as long-range dust transport make a considerable contribution. The Single Scattering Albedo (SSA) increased steadily from 2001 to 2012 by more than 0.05. In contrast, aerosol absorption has been getting stronger since 2013, with SSA increasing by 0.03, due to a much larger reduction in sulfate and nitrate. The drastic transition of aerosol properties has greatly changed aerosol radiative forcing (ARF) in eastern China. The negative ARF at the top (TOA) and bottom (BOA) of the atmosphere decreased by 30 and 50 W/m(2), respectively, in Beijing during the 2001-2012 period. Although aerosol loading continued to decline after 2013, the magnitudes of TOA and BOA ARF have increased by 10 and 30 W/m(2), respectively, since 2013, due largely to the enhanced aerosol absorption. Our results suggest that more comprehensive observations are needed to improve understanding of the intense climate and environment effects of dramatic aerosol properties in eastern China.