A closure study of aerosol optical properties as a function of RH using a κ-AMS-BC-Mie model in Beijing, China

Zou, Jianan; Yang, Shuang-Hong; Hu, Bo; Liu, Zirui; Gao, Wenkang; Xu, Hanbing; Du, Chaojie; Wei, Jie; Ma, Yongjing; Ji, Dongsheng; Wang, Yuesi

doi:10.1016/j.atmosenv.2018.10.015

Cited by 15 publications

(8 citation statements)

References 73 publications

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“…The bulk κ is largely modulated by secondary inorganic compositions given their larger κ. The κ on the ground showed consistent 0.22±0.02 (range of 0.20-0.25) under all conditions, which was in the middle range of previous ground measurements in Beijing (Wang and Chen, 2019;Wu et al, 2016;Zou et al, 2019;Liu et al, 2013a), and the observations here extend the hygroscopicity information to the upper level. As shown in Figure 4a, the vertical profiles of κ under hRH show a pronounced increase from surface level to the top of PBL with a variation from 0.18 to 0.34 by a factor of 1.9.…”

Section: Vertical Characterization Of Aerosol Chemical Compositionsupporting

confidence: 84%

“…Recent study found in Beijing most aerosols deliquesced at RH~60% (Zou et al, 2019), a criteria with surface RH above or below 60% is thus set to investigate the potential moisture influence on the observed composition, defined as high RH (hRH) and low RH (lRH) respectively. For lRH cases, the profiles were further classified as more polluted condition when surface PM1 > 100 μg m -3 .…”

Section: Aerosol Optical Propertiesmentioning

confidence: 99%

“…A single hygroscopicity parameter(κ) (Petters and Kreidenweis, 2007) is used to describe the composition effect on hygroscopicity, under both sub-and super-saturation condition (Petters and Kreidenweis, 2008). The aerosol composition measurements were intensively conducted on the ground at East Asia region in recent decade (Meng et al, 2014;Wu et al, 2016;Zou et al, 2019;Irwin et al, 2011). These studies computed the measured compositions by volume-weighted fractions to estimate the κ, and found κ ranging from 0.1 -0.4 under different environments or pollution sources, in particular, the secondary inorganics is in consensus found to be the main component driving the liquid water content in aerosol (Pringle et al, 2010;Prenni, 2003;Khlystov, 2005).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Vertical characteristics of aerosol hygroscopicity and impacts on optical properties over the North China Plain during winter

Liu¹,

Liu²,

Gao³

et al. 2019

Preprint

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Abstract. The water-uptake on aerosol influences its optical depth and capacity of cloud formation, depending on the vertical profile of aerosol hygroscopicity because of different solar radiation received and supersaturation conditions at different atmospheric levels. Such information is lack over the polluted eastern Asian region. This study presents aircraft in-situ measured aerosol size distribution and chemical compositions by series of flights over Beijing area in wintertime. Under high relative humidity conditions (surface RH > 60 %, hRH), a significant enhancement of aerosol hygroscopicity parameter (κ) in the planetary boundary layer (PBL) was observed to increase by 50 % up to 0.32 from the surface to the top of PBL (vertical gradient of ~0.13 km−1), along with the dry particle effective diameter (Deff) increased by 71 % and activation ratio up to 0.23 (0.64) at SS = 0.05 % (0.1 %), in contrast with a lower vertical gradient of κ (0.05 km−1) and smaller Deff under low RH conditions (surface RH

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Section: Vertical Characterization Of Aerosol Chemical Compositionsupporting

confidence: 84%

Section: Aerosol Optical Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Vertical characteristics of aerosol hygroscopicity and impacts on optical properties over the North China Plain during winter

Liu¹,

Liu²,

Gao³

et al. 2019

Preprint

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“…The absorption coefficient of PM 2.5 at 880 nm is calculated by the BC monitor (Han et al, 2015;Zou et al, 2019). To facilitate comparisons, absorption coefficients at 880 nm are transformed into those at 525 nm by assuming that the absorption coefficient is inversely proportional to the wavelength (Bond and Bergstrom, 2006;C.…”

Section: Methodsmentioning

confidence: 99%

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Li¹

2021

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Liquid water in aerosol particles has a significant effect on optical properties, especially on light scattering, whose dependence on chemical composition is investigated here using measurements made in southern Beijing in 2019. The effect is measured by the enhancement of aerosol hygroscopic factor, f(RH = 85%, 525 nm), which is found to be positively and negatively impacted by the proportions of inorganic and organic matters respectively. Black carbon is also negatively correlated.The positive impact is more robust when the inorganic matter mass fraction was smaller than 40% (correlation coefficient, R = 0.93) which becomes weaker as the inorganic matter mass fraction gets larger (R = 0.48). A similar pattern was also found in the negative impact for organic matter mass fraction. Nitrate played a more significant role in aerosol hygroscopicity than sulfate in Beijing. However, the deliquescence point of ambient aerosols was at about RH = 80% when the ratio of the sulfate mass concentration to the nitrate mass concentration of the aerosol was high (mostly higher than ~4). Two schemes to parameterize f(RH) were developed in accounting for the deliquescent and non-deliquescent effects. Using only one f(RH) parameterization scheme to fit all f(RH) processes would incur large errors. A piecewise parameterization scheme is proposed, which can better describe deliquescence and reduces uncertainties in simulating aerosol hygroscopicity.

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“…A single hygroscopicity parameter (κ) (Petters and Kreidenweis, 2007) is used to describe the composition effect on hygroscopicity, under both sub-and supersaturation conditions (Petters and Kreidenweis, 2008). The aerosol composition measurements were intensively conducted on the ground in the East Asian region in recent decades (Meng et al, 2014;Wu et al, 2016;Zou et al, 2019;Irwin et al, 2011). These studies computed the measured compositions by volume-weighted fractions to estimate the κ, and found κ to be ranging from 0.1 to 0.4 under different environments or pollution sources; in particular, the secondary inorganics are in consensus found to be the main component driving the liquid water content in aerosol (Pringle et al, 2010;Prenni, 2003;Khlystov, 2005).…”

Section: Introductionmentioning

confidence: 99%

Vertical characteristics of aerosol hygroscopicity and impacts on optical properties over the North China Plain during winter

Liu

Gao

et al. 2020

Atmos. Chem. Phys.

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Abstract. The water uptake of aerosol influences its optical depth and capacity for cloud formation, depending on the vertical profile of aerosol hygroscopicity because of different solar radiation received and supersaturation (SS) conditions at different atmospheric levels. Such information is lacking over the polluted East Asian region. This study presents aircraft-based in situ measured aerosol size distributions and chemical compositions by a series of flights over the Beijing area in wintertime. Under high relative humidity (hRH) conditions (surface RH > 60 %), a significant enhancement of aerosol hygroscopicity parameter (κ) in the planetary boundary layer (PBL) was observed to increase by 50 % from 0.20 up to 0.34 from the surface to the top of the PBL (vertical gradient of ∼0.13 km−1), along with the dry particle effective diameter (Deff) being increased by 71 % and activation ratio up to 0.23 (0.64) at SS =0.05 % (0.1 %). However, a lower vertical gradient of κ (0.05 km−1) and smaller Deff was exhibited under low RH (lRH, surface RH < 60 %). This suggests that the aqueous processes played an important role in promoting the enhancement of particle hygroscopicity in the PBL. The κ in the lower free troposphere (LFT) was relatively stable at 0.24±0.03 with a slight increase during regional transport. The enhancement of aerosol optical depth (AOD) due to water uptake ranged 1.0–1.22 for the PBL under lRH and LFT, but it reached as high as 6.4 in the PBL under hRH. About 80 % and 18 % of the AOD were contributed to by aerosol hygroscopic growth under hRH and lRH, respectively. These results emphasize the important evolution of aerosol water-uptake capacity in the PBL, especially under the high RH condition.

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A closure study of aerosol optical properties as a function of RH using a κ-AMS-BC-Mie model in Beijing, China

Cited by 15 publications

References 73 publications

Vertical characteristics of aerosol hygroscopicity and impacts on optical properties over the North China Plain during winter

Vertical characteristics of aerosol hygroscopicity and impacts on optical properties over the North China Plain during winter

Reply on RC2

Vertical characteristics of aerosol hygroscopicity and impacts on optical properties over the North China Plain during winter

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