3 research outputs found
Changes in Aerosol Light Absorption Observed in East Asia during the COVID-19 Lockdown
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(2015-2019) νκ· λλΉ μ½ 31-46% κ°μνμλ€. λκΈ° κΈ°μ£Όμμμ μμ΄λ‘μ‘Έ κ΄ν‘μ μ λλ₯Ό λνλ΄λ κ΄ν‘μ μμ΄λ‘μ‘Έ κ΄νλκ» μμ κ°μ κΈ°κ° μ½ 22-34% κ°μνλ νΉμ±μ 보μλ€.
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3μ μ°κ΅¬ λμμ§μμμ μ½ 17-28% κ°μνμμΌλ, λκΈ° μ€ μμ΄λ‘μ‘Έμ μν μ§μ 볡μ¬κ°μ ν¨μ¨μ μ€νλ € μ΄μ 5λ
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-2019λ
)κ³Ό λΉκ΅νμ¬ μ½ 24-36% λκ² λνλ¬λ€. μ½λ‘λ19 κΈ°κ° μ€ μ°λ μμ΄λ‘μ‘Έμ λλ ·ν κ°μλ κ΄ν‘μ μμ΄λ‘μ‘Έμ μλμ λΉμ¨ μ¦κ°λ‘ κ·κ²°λμμΌλ©°, μ΄λ μμ΄λ‘μ‘Έ κ΄νλκ»μ κ°μ λλΉ λ³΅μ¬κ°μ λ ₯μ κ°μκ° μ κ² λνλλ μ£Όμν μμΈμ΄ λμλ€.Anthropogenic aerosol and precursor emissions decreased due to the lockdown measures implemented to stop the spread of COVID-19 that started in January 2020. In this study, the changes in the light absorption characteristics of aerosols observed in East Asia and the climate effects were investigated using the ground in-situ observation data and column observation data through AERONET.
Although differences in the pattern of changes in aerosol optical properties according to regions, in February and March 2020, aerosol optical depth (AOD) significantly decreased over East Asia. In particular, in March 2020, AOD decreased by 31-46% compared to the previous 5-year mean. Absorption aerosol optical depth (AAOD), which indicates the degree of aerosol light absorption in the atmospheric column, also decreased by 22-34% during the same period.
The surface aerosol scattering coefficient observed at Anmyon decreased by about 20% in March-April compared to the previous 5-year mean, whereas the aerosol absorption coefficient showed no significant difference. PSCF analysis confirmed that the aerosol absorption coefficient in 2020 was strongly affected by the light absorbing aerosols from domestic sources.
The aerosol direct radiative forcing at the surface decreased by 17-28 % due to the decrease of AOD, but the direct radiative forcing efficiency at the atmosphere increased by 24-36% in March 2020 compared to the previous 5 years. The ratio of light absorbing aerosol to scattering aerosol increased, and the decrease in radiative forcing was small compare to the decrease of AOD.μ 1 μ₯ μ λ‘ 1
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μ 4 μ₯ κ²°λ‘ λ° μ μΈ 29
μ°Έκ³ λ¬Έν 31
Abstract 37μ
EXAMINATION OF PHOTOCHEMISTRY AND METEOROLOGY OF ATMOSPHERIC POLLUTANTS FROM THE NORTH CHINA PLAIN
Increasingly severe air pollution over metropolitan regions in China has raised attention in light of its local and regional impacts on health and climate. Computer models can simulate complex interactions between photochemistry and meteorology to inform policy decisions in reducing ground-level pollution. However, models rely on an accurate portrayal of emissions that often possess large uncertainties over regions with evolving pollution characteristics. This work is comprised of a quantitative analysis of air pollutants in the North China Plain that strives to improve such uncertainties by identification of important sources and meteorological conditions for pollution through the combination of observations and models. Measurements used in this dissertation focus on in situ observations from the Spring 2016 Air chemistry Research in Asia (ARIAs) campaign, which sampled atmospheric composition across the heavily populated and industrialized Hebei Province in the North China Plain. High amounts of ozone (O3) precursors were found throughout and even above the planetary boundary layer, continuing to generate O3 at high rates to be potentially transported downwind. Evidence for the importance of anthropogenic VOCs on O3 production is presented. Concentrations of NOx and VOCs even in the rural areas of this highly industrialized province promote widespread O3 production and in order to improve air quality over Hebei, both NOx and VOCs should be regulated. The ARIAs airborne measurements also provide a critical opportunity to characterize chlorofluorocarbons (CFCs) over a suspected CFC-11 source region in China, finding mixing ratios were well above 2016 global background levels. Based on correlations of CFCs with compounds used in their manufacture, I identify likely source regions of new CFCs production and release, in violation of the Montreal Protocol. Finally, I examine the influence of meteorology on surface and aloft measurements during ARIAs. A multiday persistent high pressure episode is presented as a case study to examine the influence of regional transport on air quality measured during ARIAs. This dissertation provides valuable information for understanding one of the most polluted regions in China. Coordinated field and modeling efforts can together provide scientific guidance to inform pollution control measures to meet air quality targets in China