Long-term variations in aerosol optical properties, types, and radiative forcing in the Sichuan Basin, Southwest China

Zhuozhi Shu; Yubao Liu; Tianliang Zhao; Yongbo Zhou; Birhanu Asmerom Habtemicheal; Lijuan Shen; Jun Hu; Xiaodan Ma; Xiaoyun Sun

doi:10.1016/j.scitotenv.2021.151490

Long-term variations in aerosol optical properties, types, and radiative forcing in the Sichuan Basin, Southwest China

Sci Total Environ. 2022 Feb 10;807(Pt 2):151490. doi: 10.1016/j.scitotenv.2021.151490. Epub 2021 Nov 5.

Authors

Zhuozhi Shu¹, Yubao Liu², Tianliang Zhao³, Yongbo Zhou⁴, Birhanu Asmerom Habtemicheal⁵, Lijuan Shen⁵, Jun Hu⁶, Xiaodan Ma⁵, Xiaoyun Sun⁵

Affiliations

¹ Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science & Technology, Nanjing 210044, China; Precision Regional Earth Modeling and Information Center, Nanjing University of Information Science & Technology, Nanjing 210044, China.
² Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science & Technology, Nanjing 210044, China; Precision Regional Earth Modeling and Information Center, Nanjing University of Information Science & Technology, Nanjing 210044, China. Electronic address: Ybliu@nuist.edu.cn.
³ Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science & Technology, Nanjing 210044, China; Precision Regional Earth Modeling and Information Center, Nanjing University of Information Science & Technology, Nanjing 210044, China. Electronic address: tlzhao@nuist.edu.cn.
⁴ Precision Regional Earth Modeling and Information Center, Nanjing University of Information Science & Technology, Nanjing 210044, China.
⁵ Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science & Technology, Nanjing 210044, China.
⁶ Fujian Academy of Environmental Sciences, Fuzhou 350011, China.

PMID: 34748838
DOI: 10.1016/j.scitotenv.2021.151490

Abstract

Long-term variations in aerosol optical properties, types, and radiative forcing over the Sichuan Basin (SCB) and surrounding regions in Southwest China were investigated based on two-decade data (2001-2020) from the Moderate Resolution Imaging Spectroradiometer, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation, and the Santa Barbara DISORT Atmospheric Radiative Transfer model. The results showed that the aerosol optical depth (AOD_550nm) in the SCB, a major polluted region in Southwest China, experienced an increasing tendency at a rate of +0.052 yr^-1 during 2001-2006; thereafter, it decreased speedy up from -0.020 to -0.058 yr^-1 over recent years, whereas the interannual variation in Ångström exponent (AE_470-660nm) presented a persistently increasing trend during 2001-2020, with a rate of +0.014 yr^-1. An improved atmospheric environment but an enhanced fine particle contribution to regional aerosols in the SCB was observed. Over the polluted SCB region, the dominant aerosol types were biomass burning/urban industrial and mixed-type aerosols with the proportions of 80.7%-87.5% in regional aerosols, with a higher frequency of clean aerosols in recent years, reflecting an effect of controlling anthropogenic emission in the SCB owing to governmental regulation. By contrast, few changes were observed in the aerosol types and amounts in the eastern Tibetan Plateau (ETP), where clean continental aerosols dominate with high proportion of 93.7% in the clean atmospheric environment. A significant decline in polluted anthropogenic aerosols was observed below 3 km over the SCB, resulting in the regional aerosol extinction coefficients at 532 nm (EC_532nm) were declined by -0.22 km^-1 from 2013 to 2020. Notably, the decreases in aerosol radiative forcing within the atmosphere were found in the SCB and the adjacent northern Yunnan-Guizhou Plateau (NYGP) and ETP, with -41.6%, -33.7%, and -13.6%, respectively during 2013-2020. This indicates that such an attenuated aerosol heating rate in the atmosphere, caused by aerosol variation, could alter the atmospheric thermal structure over the SCB and surrounding areas for regional changes of environment and climate in recent years.

Keywords: Aerosol optical properties; Aerosol types; Long-term variations; Radiative forcing; Sichuan Basin.

MeSH terms

Aerosols / analysis*
Air Pollution / analysis*
China
Government Regulation

Substances

Aerosols