tetano
Editor, Senior Moderator
Sci Total Environ
. 2022 Oct 13;159435.
doi: 10.1016/j.scitotenv.2022.159435. Online ahead of print.
Changes in aerosol loading before, during and after the COVID-19 pandemic outbreak in China: Effects of anthropogenic and natural aerosol
Yuanxin Liang[SUP] 1 [/SUP], Ke Gui[SUP] 2 [/SUP], Huizheng Che[SUP] 3 [/SUP], Lei Li[SUP] 2 [/SUP], Yu Zheng[SUP] 2 [/SUP], Xutao Zhang[SUP] 2 [/SUP], Xindan Zhang[SUP] 2 [/SUP], Peng Zhang[SUP] 4 [/SUP], Xiaoye Zhang[SUP] 2 [/SUP]
Affiliations
Abstract
Anthropogenic emissions reduced sharply in the short-term during the coronavirus disease pandemic (COVID-19). As COVID-19 is still ongoing, changes in atmospheric aerosol loading over China and the factors of their variations remain unclear. In this study, we used multi-source satellite observations and reanalysis datasets to synergistically analyze the spring (February-May) evolution of aerosol optical depth (AOD) for multiple aerosol types over Eastern China (EC) before, during and after the COVID-19 lockdown period. Regional meteorological effects and the radiative response were also quantitatively assessed. Compared to the same period before COVID-19 (i.e., in 2019), a total decrease of -14.6 % in tropospheric TROPOMI nitrogen dioxide (NO[SUB]2[/SUB]) and a decrease of -6.8 % in MODIS AOD were observed over EC during the lockdown period (i.e., in 2020). After the lockdown period (i.e., in 2021), anthropogenic emissions returned to previous levels and there was a slight increase (+2.3 %) in AOD over EC. Moreover, changes in aerosol loading have spatial differences. AOD decreased significantly in the North China Plain (-14.0 %, NCP) and Yangtze River Delta (-9.4 %) regions, where anthropogenic aerosol dominated the aerosol loading. Impacted by strong wildfires in Southeast Asia during the lockdown period, carbonaceous AOD increased by +9.1 % in South China, which partially offset the emission reductions. Extreme dust storms swept through the northern region in the period after COVID-19, with an increase of +23.5 % in NCP and + 42.9 % in Northeast China (NEC) for dust AOD. However, unfavorable meteorological conditions overwhelmed the benefits of emission reductions, resulting in a +20.1 % increase in AOD in NEC during the lockdown period. Furthermore, the downward shortwave radiative flux showed a positive anomaly due to the reduced aerosol loading in the atmosphere during the lockdown period. This study highlights that we can benefit from short-term controls for the improvement of air pollution, but we also need to seriously considered the cross-regional transport of natural aerosol and meteorological drivers.
Keywords: Aerosol optical depth; Anthropogenic aerosol; COVID-19 impacts over China; Meteorological drivers; Natural aerosol; Radiative flux.
. 2022 Oct 13;159435.
doi: 10.1016/j.scitotenv.2022.159435. Online ahead of print.
Changes in aerosol loading before, during and after the COVID-19 pandemic outbreak in China: Effects of anthropogenic and natural aerosol
Yuanxin Liang[SUP] 1 [/SUP], Ke Gui[SUP] 2 [/SUP], Huizheng Che[SUP] 3 [/SUP], Lei Li[SUP] 2 [/SUP], Yu Zheng[SUP] 2 [/SUP], Xutao Zhang[SUP] 2 [/SUP], Xindan Zhang[SUP] 2 [/SUP], Peng Zhang[SUP] 4 [/SUP], Xiaoye Zhang[SUP] 2 [/SUP]
Affiliations
- PMID: 36244490
- DOI: 10.1016/j.scitotenv.2022.159435
Abstract
Anthropogenic emissions reduced sharply in the short-term during the coronavirus disease pandemic (COVID-19). As COVID-19 is still ongoing, changes in atmospheric aerosol loading over China and the factors of their variations remain unclear. In this study, we used multi-source satellite observations and reanalysis datasets to synergistically analyze the spring (February-May) evolution of aerosol optical depth (AOD) for multiple aerosol types over Eastern China (EC) before, during and after the COVID-19 lockdown period. Regional meteorological effects and the radiative response were also quantitatively assessed. Compared to the same period before COVID-19 (i.e., in 2019), a total decrease of -14.6 % in tropospheric TROPOMI nitrogen dioxide (NO[SUB]2[/SUB]) and a decrease of -6.8 % in MODIS AOD were observed over EC during the lockdown period (i.e., in 2020). After the lockdown period (i.e., in 2021), anthropogenic emissions returned to previous levels and there was a slight increase (+2.3 %) in AOD over EC. Moreover, changes in aerosol loading have spatial differences. AOD decreased significantly in the North China Plain (-14.0 %, NCP) and Yangtze River Delta (-9.4 %) regions, where anthropogenic aerosol dominated the aerosol loading. Impacted by strong wildfires in Southeast Asia during the lockdown period, carbonaceous AOD increased by +9.1 % in South China, which partially offset the emission reductions. Extreme dust storms swept through the northern region in the period after COVID-19, with an increase of +23.5 % in NCP and + 42.9 % in Northeast China (NEC) for dust AOD. However, unfavorable meteorological conditions overwhelmed the benefits of emission reductions, resulting in a +20.1 % increase in AOD in NEC during the lockdown period. Furthermore, the downward shortwave radiative flux showed a positive anomaly due to the reduced aerosol loading in the atmosphere during the lockdown period. This study highlights that we can benefit from short-term controls for the improvement of air pollution, but we also need to seriously considered the cross-regional transport of natural aerosol and meteorological drivers.
Keywords: Aerosol optical depth; Anthropogenic aerosol; COVID-19 impacts over China; Meteorological drivers; Natural aerosol; Radiative flux.