Observations of aerosol optical properties at a coastal site in Hong Kong, South China

Wang, Jiaping; Virkkula, Aki; Gao, Yuan; Lee, Shuncheng; Chi, Xuguang; Nie, Wei; Liu, Qiang; Xu, Zheng; Huang, Xin; Wang, Tao; Cui, Long; Ding, Aijun

doi:10.5194/acp-17-2653-2017

Cited by 18 publications

(6 citation statements)

References 68 publications

(82 reference statements)

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“…B scat temporal variation showed strong correlation with BBOA (r � 0.80) and the aerosol particle number concentration from 100 to 300 nm in size (N 100-300 ) (r � 0.75) (Figure 3(a)). ese results are in agreement with those reported by Wang et al [45], which suggests that mainly particles from 200 to 800 nm in size contributed to the light-scattering coefficient.…”

Section: Temporal Variations In the Aerosol Optical Propertiessupporting

confidence: 93%

Relationship between the Optical Properties and Chemical Composition of Urban Aerosol Particles in Lithuania

Pauraitė

Plauškaitė

Dudoitis

et al. 2018

Advances in Meteorology

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In situ investigation results of aerosol optical properties (absorption and scattering) and chemical composition at an urban background site in Lithuania (Vilnius) are presented. Investigation was performed in May-June 2017 using an aerosol chemical speciation monitor (ACSM), a 7-wavelength Aethalometer and a 3-wavelength integrating Nephelometer. A positive matrix factorisation (PMF) was used for the organic aerosol mass spectra analysis to characterise the sources of ambient organic aerosol (OA). Five OA factors were identified: hydrocarbon-like OA (HOA), biomass-burning OA (BBOA), more and less oxygenated OA (LVOOA and SVOOA, respectively), and local hydrocarbon-like OA (LOA). The average absorption (at 470 nm) and scattering (at 450 nm) coefficients during the entire measurement campaign were 16.59 Mm−1 (standard deviation (SD) = 17.23 Mm−1) and 29.83 Mm−1 (SD = 20.45 Mm−1), respectively. Furthermore, the absorption and scattering Angström exponents (AAE and SAE, respectively) and single-scattering albedo (SSA) were calculated. The average AAE value at 470/660 nm was 0.97 (SD = 0.16) indicating traffic-related black carbon (BCtr) dominance. The average value of SAE (at 450/700 nm) was 1.93 (SD = 0.32) and could be determined by the submicron particle (PM1) dominance versus the supermicron ones (PM > 1 µm). The average value of SSA was 0.62 (SD = 0.13). Several aerosol types showed specific segregation in the SAE versus SSA plot, which underlines different optical properties due to various chemical compositions.

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Section: Temporal Variations In the Aerosol Optical Propertiessupporting

confidence: 93%

Relationship between the Optical Properties and Chemical Composition of Urban Aerosol Particles in Lithuania

Pauraitė

Plauškaitė

Dudoitis

et al. 2018

Advances in Meteorology

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“…The meteorological data used in this model were GDAS (Global Data Assimilation System) data with a spatial resolution of 0.5 • in both latitude and longitude. In each simulation, 3000 particles were released at an altitude of 100 m above ground level (Wang et al, 2017a) and backwardly run for a 3-day period, and then the retroplume, i.e., the footprint of the surface at 100 m, was obtained following the method of Ding et al (2013b).…”

Section: Long-term Characteristics Of Brc Light Absorption At the Sormentioning

confidence: 99%

“…The BC issue has been noticed in recent years in China, including its temporal variations, emission sources and climate effect (Cao et al, 2006(Cao et al, , 2009Yang et al, 2009;Wang et al, 2017a;Huang et al, 2014) as well as its "dome effect" in modifying the boundary layer and enhancing haze pollution in megacities (Ding et al, 2016b;Wang et al, 2018). Organic matter (OM) is a large contributor to PM 2.5 in China (15-51 % of PM 2.5 ; Wang et al, 2017c), especially in the Yangtze River Delta (YRD) region, which is one of the most densely populated city clusters in eastern China and also an important agricultural center, with crops planted in both cold and warm seasons (Ding et al, 2013a).…”

Section: Introductionmentioning

confidence: 99%

Light absorption of brown carbon in eastern China based on 3-year multi-wavelength aerosol optical property observations and an improved absorption Ångström exponent segregation method

et al. 2018

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Abstract. Brown carbon (BrC), a certain group of organic carbon (OC) with strong absorption from the visible (VIS) to ultraviolet (UV) wavelengths, makes a considerable contribution to light absorption on both global and regional scales. A high concentration and proportion of OC has been reported in China, but studies of BrC absorption based on long-term observations are rather limited in this region. In this study, we reported 3-year results of light absorption of BrC based on continuous measurement at the Station for Observing Regional Processes of the Earth System (SORPES) in the Yangtze River Delta, China, combined with Mie theory calculation. Light absorption of BrC was obtained using an improved absorption Ångström exponent (AAE) segregation method. The AAE of non-absorbing coated black carbon (BC) at each time step is calculated based on Mie theory simulation, together with single particle soot photometer (SP2) and aethalometer observations. By using this improved method, the variation of the AAE over time is taken into consideration, making it applicable for long-term analysis. The annual average light absorption coefficient of BrC (b abs_BrC ) at 370 nm was 6.3 Mm −1 at the SORPES station. The contribution of BrC to total aerosol absorption (P BrC ) at 370 nm ranged from 10.4 to 23.9 % (10th and 90th percentiles, respectively), and reached up to ∼ 33 % in the openbiomass-burning-dominant season and winter. Both b abs_BrC and P BrC exhibited clear seasonal cycles with two peaks in later spring/early summer (May-June, b abs_BrC ∼ 6 Mm −1 , P BrC ∼ 17 %) and winter (December, b abs_BrC ∼ 15 Mm −1 , P BrC ∼ 22 %), respectively. Lagrangian modeling and the chemical signature observed at the site suggested that open biomass burning and residential coal/biofuel burning were the dominant sources influencing BrC in the two seasons, respectively.

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“…The largest diurnal growth was in spring: from ∼ 1.00 to ∼ 1.09. The average AAE diurnal variation is in a range that suggests it can be attributed to variations in the diameter of a BC core and a lightscattering shell coating it (e.g., Gyawali et al, 2009;Lack and Cappa, 2010;Wang et al,2016). A detailed analysis of this would require measurements with an instrument that can actually measure the BC core and shell such as the singleparticle soot photometer (SP2; e.g., Schwarz et al, 2008).…”

Section: Diurnal Cyclesmentioning

confidence: 99%

Aerosol optical properties at SORPES in Nanjing, east China

et al. 2018

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Abstract. Aerosol optical properties (AOPs) and supporting parameters – particle number size distributions, PM2.5 mass concentrations, and the concentrations of trace gases (NOx and NOy) – were measured at SORPES, a regional background station in Nanjing, China from June 2013 to May 2015. The aerosol was highly scattering: the average scattering coefficient was σsp=403 ± 314 Mm−1, the absorption coefficient σap=26 ± 19 Mm−1, and the single-scattering albedo SSA = 0.93 ± 0.03 for green light. The SSA in Nanjing appears to be slightly higher than published values from several other sites in China and elsewhere. The average Ångström exponent of absorption (AAE) for the wavelength range 370–950 nm was 1.04 and the AAE range was 0.7–1.4. These AAE values can be explained with different amounts of non-absorbing coating on pure black carbon (BC) cores and different core sizes rather than contribution by brown carbon. The AOPs had typical seasonal cycles with high σsp and σap in winter and low ones in summer: the averages were σsp=544 ± 422 and σap=36 ± 24 Mm−1 in winter and σsp=342 ± 281 and σap=20 ± 13 Mm−1 in summer. The intensive AOPs had no clear seasonal cycles, the variations in them were rather related to the evolution of pollution episodes. The diurnal cycles of the intensive AOPs were clear and in agreement with the cycle of the particle number size distribution. The diurnal cycle of SSA was similar to that of the air photochemical age, suggesting that the darkest aerosol originated from fresh traffic emissions. A Lagrangian retroplume analysis showed that the potential source areas of high σsp and σap are mainly in eastern China. Synoptic weather phenomena dominated the cycle of AOPs on a temporal scale of 3–7 days. During pollution episodes, modeled boundary layer height decreased, whereas PM2.5 concentrations and σsp and σap typically increased gradually and remained high during several days but decreased faster, sometimes by even more than an order of magnitude within some hours. During the growth phase of the pollution episodes the intensive AOPs evolved clearly. The mass scattering efficiency MSE of PM2.5 grew during the extended pollution episodes from ∼ 4 to ∼ 6 m2 g−1 and the mass fraction of BCe decreased from ∼ 10 to ∼ 3 % during the growth phase of the episodes. Particle growth resulted in the backscatter fraction decreasing from more than 0.16 to less than 0.10, SSA growing from less than 0.9 to more than 0.95, and radiative forcing efficiency (RFE) changing from less than −26 W m−2 to more than −24 W m−2, which means that the magnitude of RFE decreased. The RFE probability distribution at SORPES was clearly narrower than at a clean background site which is in agreement with a published RFE climatology.

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Observations of aerosol optical properties at a coastal site in Hong Kong, South China

Cited by 18 publications

References 68 publications

Relationship between the Optical Properties and Chemical Composition of Urban Aerosol Particles in Lithuania

Relationship between the Optical Properties and Chemical Composition of Urban Aerosol Particles in Lithuania

Light absorption of brown carbon in eastern China based on 3-year multi-wavelength aerosol optical property observations and an improved absorption Ångström exponent segregation method

Aerosol optical properties at SORPES in Nanjing, east China

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