Properties of light‐absorbing aerosols in the Nagoya urban area, Japan, in August 2011 and January 2012: Contributions of brown carbon and lensing effect

Nakayama, Tomoki; Ikeda, Yuka; Sawada, Yoshinobu; Setoguchi, Yoshitaka; Ogawa, Shuichi; Kawana, Kaori; Mochida, Michihiro; Ikemori, Fumikazu; Matsumoto, Kiyoshi; Matsumi, Yutaka

doi:10.1002/2014jd021744

Cited by 63 publications

(50 citation statements)

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“…The diurnal variations of the HGFs of the nearly hydrophobic and more hygroscopic particles were not clear, which was in contrast to a large decrease in the HGF of the more hygroscopic particles from morning to noon in Tokyo in the summer [ Mochida et al , ] and a large increase in the HGF of the nearly hydrophobic particles in Mexico City in the spring [ Wang et al , ]. Figures a–c present the time series of the mass concentrations of the chemical components in the submicrometer particles (data in Figures a–c are from Nakayama et al []). Organics, sulfate, and ammonium were the major components among those detected in this study.…”

Section: Resultsmentioning

confidence: 99%

“…The number size distributions (d N CN /dlog d dry ) of the aerosol particles under dehumidified conditions (RH: 26% ± 4% (mean ± SD)) were measured in the range of d dry from 17.5 to 982 nm with a time resolution of 5 min. The mass concentrations of OC and EC after passing through another cyclone (URG, URG‐2000‐30EHB; cutpoint: 1 µm) were measured using a semicontinuous EC/OC analyzer (Sunset Lab., model 4) with a time resolution of 1.5 h [ Nakayama et al , ]. The mass concentrations of EC and OC were not used when the mass concentrations were smaller than the sum of the mean concentrations of the blank filter period and 3 times their SD.…”

Section: Experimental Methodsmentioning

confidence: 99%

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Hygroscopicity of aerosol particles and CCN activity of nearly hydrophobic particles in the urban atmosphere over Japan during summer

et al. 2016

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We investigated the hygroscopicity of 150 nm particles and the number‐size distributions and the cloud condensation nuclei (CCN) activity of nearly hydrophobic particles in aerosols over Nagoya, Japan, during summer. We analyzed the correlations between the number concentrations of particles in specific hygroscopic growth factor (g) ranges and the mass concentrations of chemical components. This analysis suggests the association of nearly hydrophobic particles with hydrocarbon‐like organic aerosol, elemental carbon and semivolatile oxygenated organic aerosol (SV‐OOA), that of less hygroscopic particles with SV‐OOA and nitrate and that of more hygroscopic particles with low‐volatile oxygenated organic aerosol (LV‐OOA) and sulfate. The hygroscopicity parameter (κ) of organics was derived based on the g distributions and chemical composition of 150 nm particles. The κ of the organics correlated positively with the fraction of the total organic mass spectral signal at m/z 44 and the volume fraction of the LV‐OOA to the organics, indicating that organics with highly oxygenated structures including carboxylic acid groups contribute to the water uptake. The number‐size distributions of the nearly hydrophobic particles with g around 1.0 and 1.1 correlated with the mass concentrations of chemical components. The results show that the chemical composition of the particles with g around 1.0 was different between the Aitken mode and the accumulation mode size ranges. An analysis for a parameter Fmax of the curves fitted to the CCN efficiency spectra of the particles with g around 1.0 suggests that the coating by organics associated with SV‐OOA elevated the CCN activity of these particles.

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Section: Resultsmentioning

confidence: 99%

Section: Experimental Methodsmentioning

confidence: 99%

Hygroscopicity of aerosol particles and CCN activity of nearly hydrophobic particles in the urban atmosphere over Japan during summer

et al. 2016

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“…A recent chamber study coupling actual ambient air with seed BC particles implies that the timescale for E abs reaching 2.4 is only 5 h in Beijing but 18 h in Houston . Field studies conducted in recent years have also substantiated enhanced light absorption in Canada (Knox et al, 2009;Chan et al, 2011), USA (Lack et al, 2012b), UK (Liu et al, 2015) and Japan (Nakayama et al, 2014;Ueda et al, 2016). In contrast, field studies in California, USA , found a weaker light absorption enhancement (6 % on average).…”

Section: Introductionmentioning

confidence: 96%

Quantifying black carbon light absorption enhancement with a novel statistical approach

Wang

2018

Atmos. Chem. Phys.

103

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Abstract. Black carbon (BC) particles in the atmosphere can absorb more light when coated by non-absorbing or weakly absorbing materials during atmospheric aging, due to the lensing effect. In this study, the light absorption enhancement factor, E abs , was quantified using a 1-year measurement of mass absorption efficiency (MAE) in the Pearl River Delta region (PRD). A new approach for calculating primary MAE (MAE p ), the key for E abs estimation, is demonstrated using the minimum R squared (MRS) method, exploring the inherent source independency between BC and its coating materials. A unique feature of E abs estimation with the MRS approach is its insensitivity to systematic biases in elemental carbon (EC) and σ abs measurements. The annual average E abs550 is found to be 1.50±0.48 (±1 SD) in the PRD region, exhibiting a clear seasonal pattern with higher values in summer and lower in winter. Elevated E abs in the summertime is likely associated with aged air masses, predominantly of marine origin, along with long-range transport of biomassburning-influenced air masses from Southeast Asia. Coreshell Mie simulations along with measured E abs and absorption Ångström exponent (AAE) constraints suggest that in the PRD, the coating materials are unlikely to be dominated by brown carbon and the coating thickness is higher in the rainy season than in the dry season.

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“…BrC is typically quoted as having AAE values ranging from 1.5 to ≈ 7.0. 24,31,38–45 Additional experimental studies are required to fully understand the impact of BC embedded within BrC.…”

Section: Introductionmentioning

confidence: 99%

Measured Wavelength-Dependent Absorption Enhancement of Internally Mixed Black Carbon with Absorbing and Nonabsorbing Materials

You

Radney

Zachariah

et al. 2016

Environ. Sci. Technol.

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Optical absorption spectra of laboratory generated aerosols consisting of black carbon (BC) internally mixed with non-absorbing materials (ammonium sulfate, AS, and sodium chloride, NaCl) and BC with a weakly absorbing brown carbon surrogate derived from humic acid (HA) were measured across the visible to near-IR (550 nm to 840 nm). Spectra were measured in-situ using a photoacoustic spectrometer and step-scanning a supercontinuum laser source with a tunable wavelength and bandwidth filter. BC had a mass-specific absorption cross section (MAC) of 7.89 ± 0.25 m2 g−1 at λ = 550 nm and an absorption Ångström exponent (AAE) of 1.03 ± 0.09 (2σ). For internally mixed BC, the ratio of BC mass to the total mass of the mixture was chosen as 0.13 to mimic particles observed in the terrestrial atmosphere. The manner in which BC mixed with each material was determined from transmission electron microscopy (TEM). AS/BC and HA/BC particles were fully internally mixed and the BC was both internally and externally mixed for NaCl/BC particles. The AS/BC, NaCl/BC and HA/BC particles had AAEs of 1.43 ± 0.05, 1.34 ± 0.06 and 1.91 ± 0.05, respectively. The observed absorption enhancement of mixed BC relative to the pure BC was wavelength dependent for AS/BC and decreased from 1.5 at λ = 550 nm with increasing wavelength while the NaCl/BC enhancement was essentially wavelength independent. For HA/BC, the enhancement ranged from 2 to 3 and was strongly wavelength dependent. Removal of the HA absorption contribution to enhancement revealed that the enhancement was ≈ 1.5 and independent of wavelength.

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Properties of light‐absorbing aerosols in the Nagoya urban area, Japan, in August 2011 and January 2012: Contributions of brown carbon and lensing effect

Abstract: The optical properties of aerosols at 405 and 781 nm were measured in an urban site in Nagoya,

Cited by 63 publications

References 79 publications

Hygroscopicity of aerosol particles and CCN activity of nearly hydrophobic particles in the urban atmosphere over Japan during summer

Hygroscopicity of aerosol particles and CCN activity of nearly hydrophobic particles in the urban atmosphere over Japan during summer

Quantifying black carbon light absorption enhancement with a novel statistical approach

Measured Wavelength-Dependent Absorption Enhancement of Internally Mixed Black Carbon with Absorbing and Nonabsorbing Materials

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