Temporal evolution of aerosols and their extreme events in polluted Asian regions during Terra's 20-year observations

REMOTE SENSING OF ENVIRONMENT

卷:263

Article

Hu, Zhiyuan^1,2  Jin, Qinjian³  Ma, Yuanyuan⁴  Pu, Bing³  Ji, Zhenming^1,5,6  Wang, Yonghong⁷  Dong, Wenjie^1,2 

[1] Sun Yat Sen Univ, Sch Atmospher Sci, Key Lab Trop Atmosphere Ocean Syst, Minist Educ, Zhuhai 519082, Peoples R China

[2] Southern Marine Sci & Engn Guangdong Lab, Zhuhai 519082, Peoples R China

[3] Univ Kansas, Dept Geog & Atmospher Sci, Lawrence, KS 66045 USA

[4] Chinese Acad Sci, Northwest Inst Ecoenvironm & Resources, Key Lab Land Surface Proc & Climate Change Cold &, Lanzhou 730000, Peoples R China

[5] Nanjing Univ Informat Sci & Technol, Minist & Educ, Key Lab Meteorol Disaster KLME, Nanjing, Peoples R China

[6] Nanjing Univ Informat Sci & Technol, Collaborat Innovat Ctr Forecast & Evaluat Meteoro, Nanjing, Peoples R China

[7] Univ Helsinki, Inst Atmospher & Earth Syst Res Phys, Fac Sci, POB 64, Helsinki 00014, Finland

关键词: Trend;    Aerosol;    Extreme events;    Radiation;    Air pollution;    Asia;    Terra;    MERRA-2;   

DOI  :  10.1016/j.rse.2021.112541

来源: Elsevier

【 摘 要 】

Aerosol pollution is an acute environmental issue in developing countries. Asia has been experiencing rapid changes in anthropogenic aerosols during the past two decades due to fast growth in population and economy. It is still an open question how aerosol loadings, represented by aerosol optical depth (AOD), have evolved in this century, particularly during the past decade when China and India implemented a clean air act aiming to improve air quality. Based on Terra aerosol retrievals and aerosol reanalysis, a change point of AOD trend is detected at 2010 in East China versus a persistent increasing AOD trend in the Indian subcontinent with no detectable change point from 2000 to 2019. In East China, positive AOD trend (+0.11 +/- 0.022 decade- 1) is confirmed from 2000 to 2010 (hereinafter the former period) yet negative trend (-0.26 +/- 0.027 decade- 1) is identified from 2011 to 2019 (hereinafter the later period). In the Indian subcontinent, persistent positive trend (+0.04 +/- 0.001) is detected from 2000 to 2019 (hereinafter the whole period). All of these trends are attributed mainly to changes in sulfate aerosols. Further analysis of the aerosol pollution extreme events (APEE; defined as daily AOD over the long-term local 90th AOD percentile) manifest a positive trend (+0.16 +/- 0.029 decade- 1) of the APEEs' magnitude in East China during the former period yet a negative trend (-0.11 +/- 0.020 decade- 1) during the latter period; the Indian subcontinent demonstrates a positive trend (+0.02 +/- 0.004 decade- 1) during the whole period due to increasing sulfate aerosols. The APEEs have become more frequent (+3.5 +/- 0.53 day month-1 decade- 1) in East China during the former period yet less frequent (-3.6 +/- 0.39 day month-1 decade-1) during the latter period; in the Indian subcontinent, more frequent APEEs (+1.1 +/- 0.25 day month-1 decade- 1) have been detected during the whole period. Consistent with the AOD trends, clear-sky radiation in East China shows a negative trend at the surface (-3.2 +/- 0.67 W m- 2 decade- 1), a positive trend in the atmosphere (+1.4 +/- 0.68 decade- 1), and a negative trend at the top of the atmosphere (-1.8 +/- 0.43 decade- 1) during the former period, respectively; opposite trends with much larger magnitude are seen during the latter period. In the Indian subcontinent, the clear-sky radiation trends during the whole period are -1.4 +/- 0.38, +1.7 +/- 0.31, and + 0.5 +/- 0.16 W m- 2 decade- 1 at the surface, in the atmosphere, and at the top of the atmosphere, respectively. Comparison of radiation trends at clear-sky and all-sky conditions suggests that absorbing aerosols dominate the radiation budget in the atmosphere and the aerosol reanalysis of the Modern-Era Retrospective Analysis for Research ans Applications version 2 (MERRA-2) might overestimate the radiation response to clouds. This study provides an up-to-date analysis of the long-term trends in aerosols and their extreme events and radiation in two of the world's heavily polluted regions and the results have important implications for assessment of the environmental and climatic impacts of the ongoing clean air acts in Asia.

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