Aircraft Instrument for Comprehensive Characterization of Aerosol Optical Properties, Part 2: Black and Brown Carbon Absorption and Absorption Enhancement Measured with Photo Acoustic Spectroscopy

Abstract. An accurate simulation of the absorption properties is key for assessing the radiative effects of aerosol on meteorology and climate. The representation of how chemical species are mixed inside the particles (the mixing state) is one of the major uncertainty factors in the assessment of these effects. Here we compare aerosol optical properties simulations over Europe and North America, coordinated in the framework of the third phase of the Air Quality Model Evaluation International Initiative (AQMEII), to 1 year of AERONET sunphotometer retrievals, in an attempt to identify a mixing state representation that better reproduces the observed single scattering albedo and its spectral variation. We use a single post-processing tool (FlexAOD) to derive aerosol optical properties from simulated aerosol speciation profiles, and focus on the absorption enhancement of black carbon when it is internally mixed with more scattering material, discarding from the analysis scenes dominated by dust. We found that the single scattering albedo at 440 nm (ω0,440) is on average overestimated (underestimated) by 3–5 % when external (core-shell internal) mixing of particles is assumed, a bias comparable in magnitude with the typical variability of the quantity. The (unphysical) homogeneous internal mixing assumption underestimates ω0,440 by ∼14 %. The combination of external and core-shell configurations (partial internal mixing), parameterized using a simplified function of air mass aging, reduces the ω0,440 bias to -1/-3 %. The black carbon absorption enhancement (Eabs) in core-shell with respect to the externally mixed state is in the range 1.8–2.5, which is above the currently most accepted upper limit of ∼1.5. The partial internal mixing reduces Eabs to values more consistent with this limit. However, the spectral dependence of the absorption is not well reproduced, and the absorption Ångström exponent AAE675440 is overestimated by 70–120 %. Further testing against more comprehensive campaign data, including a full characterization of the aerosol profile in terms of chemical speciation, mixing state, and related optical properties, would help in putting a better constraint on these calculations.

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Modelling black carbon absorption of solar radiation: combining external and internal mixing assumptions

10.5194/acp-2018-111 ◽

2018 ◽

Author(s):

Gabriele Curci ◽

Ummugulsum Alyuz ◽

Rocio Barò ◽

Roberto Bianconi ◽

Johannes Bieser ◽

...

Keyword(s):

Optical Properties ◽

Black Carbon ◽

Single Scattering ◽

Single Scattering Albedo ◽

Absorption Enhancement ◽

Core Shell ◽

Mixing State ◽

Aerosol Optical Properties ◽

Internal Mixing ◽

Carbon Absorption

Abstract. An accurate simulation of the absorption properties is key for assessing the radiative effects of aerosol on meteorology and climate. The representation of how chemical species are mixed inside the particles (the mixing state) is one of the major uncertainty factors in the assessment of these effects. Here we compare aerosol optical properties simulations over Europe and North America, coordinated in the framework of the third phase of the Air Quality Model Evaluation International Initiative (AQMEII), to one year of AERONET sunphotometer retrievals, in an attempt to identify a mixing state representation that better reproduces the observed single scattering albedo and its spectral variation. We use a single post-processing tool (FlexAOD) to derive aerosol optical properties from simulated aerosol speciation profiles, and focus on the absorption enhancement of black carbon when it is internally mixed with more scattering material, discarding from the analysis scenes dominated by dust. We found that the single scattering albedo at 440 nm (ω0,440) is on average overestimated (underestimated) by 3–5 % when external (core-shell internal) mixing of particles is assumed, a bias comparable in magnitude with the typical variability of the quantity. The (unphysical) homogeneous internal mixing assumption underestimates ω0,440 by ~ 14 %. The combination of external and core-shell configurations (partial internal mixing), parameterized using a simplified function of air mass aging, reduces the ω0,440 bias to −1/−3 %. The black carbon absorption enhancement (Eabs) in core-shell with respect to the externally mixed state is in the range 1.8–2.5, which is above the currently most accepted upper limit of ~ 1.5. The partial internal mixing reduces Eabs to values more consistent with this limit. However, the spectral dependence of the absorption is not well reproduced, and the absorption Angostrom exponent AAE440675 is overestimated by 70–120 %. Further testing against more comprehensive campaign data, including a full characterization of the aerosol profile in terms of chemical speciation, mixing state, and related optical properties, would help in putting a better constraint on these calculations.

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Characterization of aerosol type based on aerosol optical properties over Baghdad, Iraq

Arabian Journal of Geosciences ◽

10.1007/s12517-018-3944-1 ◽

2018 ◽

Vol 11 (20) ◽

Cited By ~ 4

Author(s):

Ali M. Al-Salihi

Keyword(s):

Optical Properties ◽

Aerosol Optical Properties ◽

Aerosol Type

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Characterization of aerosol optical properties and model computed radiative forcing over a semi-arid region, Kadapa in India

Atmospheric Research ◽

10.1016/j.atmosres.2018.03.013 ◽

2018 ◽

Vol 209 ◽

pp. 36-49 ◽

Cited By ~ 7

Author(s):

C. Viswanatha Vachaspati ◽

G. Reshma Begam ◽

Y. Nazeer Ahammed ◽

K. Raghavendra Kumar ◽

R.R. Reddy

Keyword(s):

Optical Properties ◽

Arid Region ◽

Radiative Forcing ◽

Aerosol Optical Properties ◽

Semi Arid Region ◽

Semi Arid

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Airborne in situ characterization of dry urban aerosol optical properties around complex topography

Atmospheric Research ◽

10.1016/j.atmosres.2005.05.005 ◽

2006 ◽

Vol 79 (2) ◽

pp. 148-174 ◽

Cited By ~ 5

Author(s):

Admir Créso Targino ◽

Kevin J. Noone

Keyword(s):

Optical Properties ◽

Urban Aerosol ◽

Complex Topography ◽

In Situ Characterization ◽

Aerosol Optical Properties

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Optical and X-Ray Diffraction Characterization of MBE-Grown InGaAs, InAlAs and InGaAIAs on InP

MRS Proceedings ◽

10.1557/proc-340-53 ◽

1994 ◽

Vol 340 ◽

Cited By ~ 2

Author(s):

Z. C. Feng ◽

S. J. Chua ◽

A. Raman ◽

N.N. Lim

Keyword(s):

Optical Properties ◽

Fourier Transform ◽

Molecular Beam ◽

Growth Conditions ◽

X Ray Diffraction ◽

Double Crystal ◽

X Ray ◽

Lattice Matched ◽

Comprehensive Characterization

ABSTRACTA variety of Inl-xGaxAs, Inl-yAlyAs and Inl-x-yGaxAlyAs films have been grown on InP by molecular beam epitaxy. A comprehensive characterization was performed using Raman scattering, photoluminescence (PL), Fourier transform infrared (FTIR) spectroscopy and double crystal X-ray diffraction on these ternary and quaternary heterostructures with different compositions and growth conditions. The lattice matched and mismatched structures are studied. Our analyses show that the interface mismatch exerts an important influence on the optical properties of these heterostructures, and conversely that Raman, PL and FTIR can be used to probe the interface mismatch nondestructively.

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Real-Time Aerosol Optical Properties, Morphology and Mixing States under Clear, Haze and Fog Episodes in the Summer of Urban Beijing

10.5194/acp-2016-976 ◽

2017 ◽

Cited By ~ 1

Author(s):

Rui Li ◽

Yunjie Hu ◽

Ling Li ◽

Hongbo Fu ◽

Jianmin Chen

Keyword(s):

Optical Properties ◽

Size Distribution ◽

Light Absorption ◽

Large Fraction ◽

Light Extinction ◽

Absorption Enhancement ◽

Air Pollution Control ◽

Hygroscopic Growth ◽

Aerosol Optical Properties ◽

Mixing States

Abstract. Characteristics of aerosol optical properties, morphologies and their relationship were studied in urban Beijing during the clear, haze and fog episodes, sampled from 24th May to 22nd Jun, 2012. Transmission Electron Microscope (TEM), a Cavity Ring Down Spectrometer (CRDS), a nephelometer and an aethalometer were employed to investigate the corresponding changes of the aerosol properties. Five episodes were categorised according to the meteorological conditions, composition and optical variation. Results show the clear episode (EP-2 and EP-4) featured as the low light extinction with less pollutants, which are mostly externally mixed. Coarse particles were scarcely observed in EP-2 due to the washout of a previous heavy rain. Thus the size distribution in EP-2 was smaller than EP-4, which had some mineral particles introduced from the north. In contrast, industry-induced haze (EP-1) and biomass burning-induced haze (EP-5) were both impacted by the south air mass. Higher AOD (Aerosol Optical Depth) values illustrated heavy loading particle concentrations. Due to the collision, size of most particles was larger with the diameter of 1 μm, resulting in a higher scattering coefficient. However, as the influence of severe crop residue combustion, a large fraction of soot was detected, which sticks to the KCl transformed sulphate or nitrate particles. The light absorption enhancement was contributed by both Black Carbon (BC) acceleration and other light absorbing substances. Comparatively, soot fog period detected in EP-3 was mostly internally mixed with sulphates and nitrates, which revealed themselves after electron exposure. The larger size distribution was likely to be caused by both hygroscopic growth and collision. More internally mixed particles were observed, which favored the light absorption. The comparison of all the episodes provides a deeper insight of how mixing states influence the aerosol extinction properties and also a clue to the air pollution control in the crop burning seasons.

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