Recent Progress of Aerosol Light-scattering Enhancement Factor Studies in China

Zhao, Chunsheng; Yu, Yingli; Kuang, Ye; Tao, Jiangchuan; Zhao, Gang

doi:10.1007/s00376-019-8248-1

Cited by 38 publications

(21 citation statements)

References 42 publications

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“…High levels of fine particulate matter (PM2.5) concentrations influence people's daily lives and threaten public health (Liu et al, 2019;Zhao et al, 2018a;Hong et al, 2019;. In addition, they are efficient in scattering and absorbing solar radiation, and are involved in the climate change by changing the surface energy budget (Wang et al, 2009;Wang et al, 2017;Bi et al, 2016;Chen et al, 2019b;Zhao et al, 2019b;Che et al, 2019). To mitigate PM2.5 pollutions, the Chinese government issued the Air Pollution Prevention and Control Action Plan (hereinafter referred to as the Clean Air Action hereinafter) in 2013, which required the Beijing-Tianjin-Hebei (BTH) region, Yangtze River Delta and Pearl River Delta to reduce their PM2.5 concentrations by 15~25% from 2013 to 2017 (China's State Council, 2013).…”

Section: Introductionmentioning

confidence: 99%

Effects of atmospheric circulations on the interannual variation in PM2.5 concentrations over the Beijing-Tianjin-Hebei region in 2013–2018

Wang¹,

Zhang²

2020

Preprint

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Abstract. The Chinese government has made many efforts to mitigate fine particulate matter (PM2.5) pollution in recent years by taking strict measures on air pollutants reduction, which has generated the nationwide improvements in air quality since 2013. However, under the stringent air pollution controls, how PM2.5 concentration varies and how much the meteorological conditions contribute to the interannual variations in PM2.5 concentrations are still unclear, which is very important for the local government to assess the emission reduction of previous year and adjust mitigation strategies of next year. The effects of atmospheric circulation on the interannual variation in wintertime PM2.5 concentrations over the Beijing-Tianjin-Hebei (BTH) region in the period of 2013–2018 are evaluated in this study. Generally, the transport of clean and dry air masses and unstable boundary layer working with the effective near-surface horizontal divergence or pumping action at the top of the boundary layer benefit for the horizontal or vertical diffusion of surface air pollutants. Instead, the co-occurrence of a stable boundary layer, frequent air stagnation, positive water vapor advection and deep near-surface horizontal convergence exacerbate the air pollution. Favorable circulation conditions lasting for 2~4 days are beneficial for the diffusion of air pollutants, and 3~7 days of unfavorable circulation events exacerbate the accumulation of air pollutants. The occurrence frequency of favorable circulation events is consistent with the interannual variation in seasonal mean PM2.5 concentrations. There is better diffusion ability in the winters of 2014 and 2017 than in other years. A 76.5 % of the observed decrease in PM2.5 concentrations in 2017 over the BTH region could be attributed to the improvement in atmospheric diffusion conditions. It is essential to exclude the contribution of meteorological conditions to the variation in interannual air pollutants when making a quantitative evaluation of emission reduction measurements.

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Section: Introductionmentioning

confidence: 99%

Effects of atmospheric circulations on the interannual variation in PM2.5 concentrations over the Beijing-Tianjin-Hebei region in 2013–2018

Wang¹,

Zhang²

2020

Preprint

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“…Aerosol particles grow up in size as ambient RH increases, further enhances their extinction coefficient and impacts visibility (Zhao et al, 2019;Kuang et al, 2016). In this section, size-resolved extinction coefficient of aerosol particles was estimated, and the influences of liquid water on the extinction coefficient and visibility were quantitatively evaluated.…”

Section: The Key Role Of Liquid Water On Visibility Degradationmentioning

confidence: 99%

Mutual promotion effect between aerosol particle liquid water and nitrate formation lead to severe nitrate-dominated particulate matter pollution and low visibility

Wang¹,

Chen²,

Wu³

et al. 2019

Preprint

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Abstract. As has been the case in North America and Western Europe, the SO2 emissions substantially reduced in North China Plain (NCP) in recent years. A dichotomy of reductions in SO2 and NOx concentrations result in the frequent occurrences of nitrate (pNO3&#8722;)-dominated particulate matter pollution over NCP. In this study, we observed a polluted episode with the nitrate mass fraction in non-refractory PM1 (NR-PM1) up to 44&#8201;% during wintertime in Beijing. Based on this typical pNO3&#8722;-dominated haze event, the linkage between aerosol water uptake and pNO3&#8722; formation, further impacting on visibility degradation, have been investigated based on field observations and theoretical calculations. During haze development, as ambient relative humidity (RH) increased from ~&#8201;10&#8201;% up to 70&#8201;%, the aerosol particle liquid water increased from ~&#8201;1&#8201;&#956;g/m3 at the beginning to ~&#8201;75&#8201;&#956;g/m3 at the fully-developed haze period. Without considering the water uptake, the particle surface area and the volume concentrations increased by a factor of 4.1 and 4.8, respectively, during the development of haze event. Taking water uptake into account, the wet particle surface area and volume concentrations enhanced by a factor of 4.7 and 5.8, respectively. As a consequence, the hygroscopic growth of particles facilitated the condensational loss of dinitrogen pentoxide (N2O5) and nitric acid (HNO3) to particles contributing pNO3&#8722;. From the beginning to the fully-developed haze, the condensational loss of N2O5 increased by a factor of 20 when only considering aerosol surface area and volume of dry particles, while increasing by a factor of 25 considering extra surface area and volume due to water uptake. Similarly, the condensational loss of HNO3 increased by a factor of 2.7~2.9 and 3.1~3.5 for dry and wet aerosol surface area and volume from the beginning to the fully-developed haze period. Above results demonstrated that the pNO3&#8722; formation is further enhanced by aerosol water uptake with elevated ambient RH during haze development, in turn, facilitating the aerosol taking up water due to the hygroscopicity of nitrate salt. Such mutual promotion effect between aerosol particle liquid water and nitrate formation can rapidly degrade air quality and halve visibility within one day. Reduction of nitrogen-containing gaseous precursors, e.g., by control of traffic emissions, is essential in mitigating severe haze events in NCP.

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“…Due to their hygroscopicity, aerosol particles will take up water (i.e., hygroscopic growth) and lead to an increase in particle mass and size (Kreidenweis and Asa-Awuku, 2014;Tang et al, 2016;Tang et al, 2019). Therefore, hygroscopicity largely determines optical properties of aerosols and as a result their impacts on visibility and direct radiative forcing under subsaturated conditions (Titos et al, 2016;Zhao et al, 2019); on the other hand, hygroscopicity is also closely linked to CCN activities of aerosols and thus their abilities to form cloud droplets under supersaturated conditions (Kreidenweis and Asa-Awuku, 2014;Farmer et al, 2015;Tang et al, 2016), thereby having important implications for their indirect radiative forcing (Dusek et al, 2006;McFiggans et al, 2006;Farmer et al, 2015). Furthermore, hygroscopicity determines aerosol liquid water content (ALWC) and thus phase state, acidity, and chemical reactivities of aerosols (Bertram and Thornton, 2009;Liu et al, 2017;Tang et al, 2017;, playing critical roles in secondary aerosol formation and the removal and production of trace gases.…”

Section: Introductionmentioning

confidence: 99%

Tropospheric aerosol hygroscopicity in China

Peng

Wang

et al. 2020

Atmos. Chem. Phys.

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Abstract. Hygroscopicity largely determines phase state, chemical reactivity, optical properties, and cloud nucleation activities of aerosol particles, thus significantly affecting their impacts on visibility, atmospheric chemistry, and climate. In the last 20 years, a large number of field studies have investigated the hygroscopicity of tropospheric aerosols in China under subsaturated and supersaturated conditions. Aerosol hygroscopicity measurements in China are reviewed in this paper: (1) a comprehensive summary and critical discussion of aerosol hygroscopicity measurements in China are provided; (2) available measurement data are compiled and presented under a consistent framework to enhance their accessibility and usability; and (3) current knowledge gaps are identified, and an outlook which could serve as guidelines for planning future research is also proposed.

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Recent Progress of Aerosol Light-scattering Enhancement Factor Studies in China

Cited by 38 publications

References 42 publications

Effects of atmospheric circulations on the interannual variation in PM<sub>2.5</sub> concentrations over the Beijing-Tianjin-Hebei region in 2013–2018

Effects of atmospheric circulations on the interannual variation in PM<sub>2.5</sub> concentrations over the Beijing-Tianjin-Hebei region in 2013–2018

Mutual promotion effect between aerosol particle liquid water and nitrate formation lead to severe nitrate-dominated particulate matter pollution and low visibility

Tropospheric aerosol hygroscopicity in China

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Recent Progress of Aerosol Light-scattering Enhancement Factor Studies in China

Cited by 38 publications

References 42 publications

Effects of atmospheric circulations on the interannual variation in PM&lt;sub&gt;2.5&lt;/sub&gt; concentrations over the Beijing-Tianjin-Hebei region in 2013–2018

Effects of atmospheric circulations on the interannual variation in PM&lt;sub&gt;2.5&lt;/sub&gt; concentrations over the Beijing-Tianjin-Hebei region in 2013–2018

Mutual promotion effect between aerosol particle liquid water and nitrate formation lead to severe nitrate-dominated particulate matter pollution and low visibility

Tropospheric aerosol hygroscopicity in China

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Product

Resources

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Effects of atmospheric circulations on the interannual variation in PM<sub>2.5</sub> concentrations over the Beijing-Tianjin-Hebei region in 2013–2018

Effects of atmospheric circulations on the interannual variation in PM<sub>2.5</sub> concentrations over the Beijing-Tianjin-Hebei region in 2013–2018