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Journal articles on the topic 'Absorption Ångstrom exponent'

Author: Grafiati

Published: 3 June 2025

Last updated: 31 July 2025

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1

Cheng, Yi, Junfang Mao, Zhe Bai, et al. "The Significant Contribution of Polycyclic Aromatic Nitrogen Heterocycles to Light Absorption in the Winter North China Plain." Sustainability 15, no. 11 (2023): 8568. http://dx.doi.org/10.3390/su15118568.

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By quantifying the absorption of black carbon (BC), brown carbon (BrC) and the lensing effect, we found that BrC dominates the total absorption at 450 nm, and the largest absorption contribution proportion of BrC could reach 78.3% during heavy pollution. The average absorption enhancement (Eabs) at 530 nm was only 1.38, indicating that BC is not coated well here. The average value of the absorption Ångstrom exponent (AAE) between 450 nm and 530 nm was 5.3, suggesting a high concentration of BrC in Wangdu. CHN+ was the greatest contributor to the light absorption of molecules detected in MSOC w

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2

Zhang, Xiaolin, Mao Mao, Yan Yin, and Shihao Tang. "The absorption Ångstrom exponent of black carbon with brown coatings: effects of aerosol microphysics and parameterization." Atmospheric Chemistry and Physics 20, no. 16 (2020): 9701–11. http://dx.doi.org/10.5194/acp-20-9701-2020.

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Abstract. The aerosol absorption Ångstrom exponent (AAE) is a crucial optical parameter for apportionment and characterization. Due to considerable inconsistences associated with observations, numerical research is a powerful means to give a better understanding of the AAE of aged black carbon (BC) aerosols. Numerical studies of the AAE of polydisperse BC aggregates with brown coatings using the exact multiple-sphere T-matrix method (MSTM) are performed. The objective of the study is to thoroughly assess the AAE of coated BC influenced by their observation-based detailed microphysics and then

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3

Lack, D. A., R. Bahreni, J. M. Langridge, J. B. Gilman, and A. M. Middlebrook. "Brown carbon absorption linked to organic mass tracers in biomass burning particles." Atmospheric Chemistry and Physics Discussions 12, no. 11 (2012): 29129–46. http://dx.doi.org/10.5194/acpd-12-29129-2012.

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Abstract. Traditional gas and particle phase chemical markers used to identify the presence of biomass burning (BB) emissions were measured for a large forest fire near Boulder, Colorado. Correlation of the mass spectroscopic marker of levoglucosan (m/z 60) with measured particle light absorption properties found no link at 532 nm, and a strong correlation at 404 nm. Non-black carbon (BC) absorption at 404 nm was well correlated to the ratio of the mass fractions of particulate organic matter (POM) that were m/z 60 (f60) to m/z 44 (f44). The f60 to f44 ratio did not fully explain the variabili

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4

Doherty, S. J., S. G. Warren, T. C. Grenfell, A. D. Clarke, and R. E. Brandt. "Light-absorbing impurities in Arctic snow." Atmospheric Chemistry and Physics 10, no. 23 (2010): 11647–80. http://dx.doi.org/10.5194/acp-10-11647-2010.

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Abstract. Absorption of radiation by ice is extremely weak at visible and near-ultraviolet wavelengths, so small amounts of light-absorbing impurities in snow can dominate the absorption of solar radiation at these wavelengths, reducing the albedo relative to that of pure snow, contributing to the surface energy budget and leading to earlier snowmelt. In this study Arctic snow is surveyed for its content of light-absorbing impurities, expanding and updating the 1983–1984 survey of Clarke and Noone. Samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Oc

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5

Lack, D. A., R. Bahreini, J. M. Langridge, J. B. Gilman, and A. M. Middlebrook. "Brown carbon absorption linked to organic mass tracers in biomass burning particles." Atmospheric Chemistry and Physics 13, no. 5 (2013): 2415–22. http://dx.doi.org/10.5194/acp-13-2415-2013.

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Abstract. Traditional gas and particle phase chemical markers used to identify the presence of biomass burning (BB) emissions were measured for a large forest fire near Boulder, Colorado. Correlation of the organic matter mass spectroscopic m/z 60 with measured particle light absorption properties found no link at 532 nm, and a strong correlation at 404 nm. Non-black carbon absorption at 404 nm was well correlated to the ratio of the mass fractions of particulate organic matter (POM) that was m/z 60 (f60) to m/z 44 (f44). The f60 to f44 ratio did not fully explain the variability in non-BC abs

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6

Doherty, S. J., S. G. Warren, T. C. Grenfell, A. D. Clarke, and R. E. Brandt. "Light-absorbing impurities in Arctic snow." Atmospheric Chemistry and Physics Discussions 10, no. 8 (2010): 18807–78. http://dx.doi.org/10.5194/acpd-10-18807-2010.

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Abstract. Absorption of radiation by ice is extremely weak at visible and near-ultraviolet wavelengths, so small amounts of light-absorbing impurities in snow can dominate the absorption of solar radiation at these wavelengths, reducing the albedo relative to that of pure snow, contributing to the surface energy budget and leading to earlier snowmelt. In this study Arctic snow is surveyed for its content of light-absorbing impurities, expanding and updating the 1983–1984 survey of Clarke and Noone. Samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Oc

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7

Lara, Pamela, Rosa M. Fitzgerald, Nakul N. Karle, et al. "Winter and Wildfire Season Optical Characterization of Black and Brown Carbon in the El Paso-Ciudad Juárez Airshed." Atmosphere 13, no. 8 (2022): 1201. http://dx.doi.org/10.3390/atmos13081201.

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Black (EBC) and Brown (BrC) Carbon are ubiquitous constituents of atmospheric particulate matter that affect people’s health, disrupt ecosystems, and modulate local and global climate. Tracking the local deposition and sources of these aerosol particles is essential to better understanding their multidimensional environmental impact. The main goal of the current study is to measure the absorption coefficient (Babs) of particles within the Planetary Boundary Layer (PBL) of the El Paso (US)–Ciudad Juárez (Mexico) airshed and assess the contribution of black and brown carbon particles to the opti

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8

Liu, J., M. Bergin, H. Guo, et al. "Size-resolved measurements of brown carbon and estimates of their contribution to ambient fine particle light absorption based on water and methanol extracts." Atmospheric Chemistry and Physics Discussions 13, no. 7 (2013): 18233–76. http://dx.doi.org/10.5194/acpd-13-18233-2013.

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Abstract. Light absorbing organic carbon, often termed brown carbon, has the potential to significantly contribute to the visible light absorption budget, particularly at shorter wavelengths. Currently, the relative contributions of particulate brown carbon to light absorption, as well as the sources of brown carbon are poorly understood. With this in mind field measurements were made at both urban (Atlanta), and rural (Yorkville) sites in Georgia. Measurements in Atlanta were made at both a central site and a road side site adjacent to a main highway near the city center. Fine particle brown

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9

Markowicz, Krzysztof M., Iwona S. Stachlewska, Olga Zawadzka-Manko, et al. "A Decade of Poland-AOD Aerosol Research Network Observations." Atmosphere 12, no. 12 (2021): 1583. http://dx.doi.org/10.3390/atmos12121583.

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The Poland-AOD aerosol research network was established in 2011 to improve aerosol–climate interaction knowledge and provide a real-time and historical, comprehensive, and quantitative database for the aerosol optical properties distribution over Poland. The network consists of research institutions and private owners operating 10 measurement stations and an organization responsible for aerosol model transport simulations. Poland-AOD collaboration provides observations of spectral aerosol optical depth (AOD), Ångstrom Exponent (AE), incoming shortwave (SW) and longwave (LW) radiation fluxes, v

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10

Rizzo, L. V., A. L. Correia, P. Artaxo, A. S. Procópio, and M. O. Andreae. "Spectral dependence of aerosol light absorption over the Amazon Basin." Atmospheric Chemistry and Physics 11, no. 17 (2011): 8899–912. http://dx.doi.org/10.5194/acp-11-8899-2011.

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Abstract. In this study, we examine the spectral dependence of aerosol absorption at different sites and seasons in the Amazon Basin. The analysis is based on measurements performed during three intensive field experiments at a pasture site (Fazenda Nossa Senhora, Rondônia) and at a primary forest site (Cuieiras Reserve, Amazonas), from 1999 to 2004. Aerosol absorption spectra were measured using two Aethalometers: a 7-wavelength Aethalometer (AE30) that covers the visible (VIS) to near-infrared (NIR) spectral range, and a 2-wavelength Aethalometer (AE20) that measures absorption in the UV and

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11

Singh, Sujeeta, Marc N. Fiddler, and Solomon Bililign. "Measurement of size-dependent single scattering albedo of fresh biomass burning aerosols using the extinction-minus-scattering technique with a combination of cavity ring-down spectroscopy and nephelometry." Atmospheric Chemistry and Physics 16, no. 21 (2016): 13491–507. http://dx.doi.org/10.5194/acp-16-13491-2016.

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Abstract. Biomass burning (BB) aerosols have a significant effect on regional climate, and represent a significant uncertainty in our understanding of climate change. Using a combination of cavity ring-down spectroscopy and integrating nephelometry, the single scattering albedo (SSA) and Ångstrom absorption exponent (AAE) were measured for several North American biomass fuels. This was done for several particle diameters for the smoldering and flaming stage of white pine, red oak, and cedar combustion. Measurements were done over a wider wavelength range than any previous direct measurement of

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12

Rizzo, L. V., A. L. Correia, P. Artaxo, A. S. Procópio, and M. O. Andreae. "Spectral dependence of aerosol light absorption over the Amazon Basin." Atmospheric Chemistry and Physics Discussions 11, no. 4 (2011): 11547–77. http://dx.doi.org/10.5194/acpd-11-11547-2011.

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Abstract. In this study, we examine the spectral dependence of aerosol absorption at different sites and seasons in the Amazon Basin. The analysis is based on measurements performed during three intensive field experiments at a pasture site (Fazenda Nossa Senhora, Rondônia) and at a primary forest site (Cuieiras Reserve, Amazonas), from 1999 to 2004. Aerosol absorption spectra were measured using two Aethalometers: a 7-wavelength Aethalometer (AE30) that covers the visible (VIS) to near-infrared (NIR) spectral range, and a 2-wavelength Aethalometer (AE20) that measures absorption in the UV and

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13

Pandolfi, M., M. Cusack, A. Alastuey, and X. Querol. "Variability of aerosol optical properties in the Western Mediterranean Basin." Atmospheric Chemistry and Physics Discussions 11, no. 5 (2011): 14091–125. http://dx.doi.org/10.5194/acpd-11-14091-2011.

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Abstract. Aerosol light scattering, black carbon (BC) and particulate matter (PM) concentrations were measured at Montseny, a regional background site in the Western Mediterranean Basin (WMB) which is part of the European Supersite for Atmospheric Aerosol Research (EUSAAR). Off line analyses of 24 h PM filters collected with Hi-Vol instruments were performed for the determination of the main chemical components of PM. Measurements of BC were used to calculate the light absorption properties of atmospheric particles. Single Scattering Albedo (SSA) at 635 nm was estimated starting from aerosol s

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14

Schnaiter, M., M. Gimmler, I. Llamas, C. Linke, C. Jäger, and H. Mutschke. "Strong spectral dependence of light absorption by organic carbon particles formed by propane combustion." Atmospheric Chemistry and Physics Discussions 6, no. 2 (2006): 1841–66. http://dx.doi.org/10.5194/acpd-6-1841-2006.

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Abstract. We have measured the extinction and absorption cross sections of carbon particles emitted by a propane diffusion flame both in an aerosol chamber and on size-segregated samples deposited on optical windows. The absorption cross section, the single scattering albedo and the Ångström exponent show drastic dependencies both on the C/O ratio and on the particle size. This is interpretated as being due to the appearance of nucleation modes of smaller organic particles at higher C/O ratios, which were detected by SMPS measurements and partially by TEM analysis. The spectral range of the va

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15

Schnaiter, M., M. Gimmler, I. Llamas, C. Linke, C. Jäger, and H. Mutschke. "Strong spectral dependence of light absorption by organic carbon particles formed by propane combustion." Atmospheric Chemistry and Physics 6, no. 10 (2006): 2981–90. http://dx.doi.org/10.5194/acp-6-2981-2006.

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Abstract. We have measured the extinction and absorption cross sections of carbon particles emitted by a propane diffusion flame both in an aerosol chamber and on size-segregated samples deposited on optical windows. The absorption cross section, the single scattering albedo, and the Ångström exponent show drastic dependencies both on the C/O ratio and on the particle size. This is interpretated as being due to the appearance of nucleation modes of smaller organic particles at higher C/O ratios, which were detected by SMPS measurements and partially by TEM analysis. The spectral range of the v

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16

Pandolfi, M., M. Cusack, A. Alastuey, and X. Querol. "Variability of aerosol optical properties in the Western Mediterranean Basin." Atmospheric Chemistry and Physics 11, no. 15 (2011): 8189–203. http://dx.doi.org/10.5194/acp-11-8189-2011.

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Abstract. Aerosol light scattering, absorption and particulate matter (PM) concentrations were measured at Montseny, a regional background site in the Western Mediterranean Basin (WMB) which is part of the European Supersite for Atmospheric Aerosol Research (EUSAAR). Off line analyses of 24 h PM filters collected with Hi-Vol instruments were performed for the determination of the main chemical components of PM. Mean scattering and hemispheric backscattering coefficients (@ 635 nm) were 26.6±23.2 Mm−1 and 4.3±2.7 Mm−1, respectively and the mean aerosol absorption coefficient (@ 637 nm) was 2.8±

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17

Liu, Chao, Chul Eddy Chung, Yan Yin, and Martin Schnaiter. "The absorption Ångström exponent of black carbon: from numerical aspects." Atmospheric Chemistry and Physics 18, no. 9 (2018): 6259–73. http://dx.doi.org/10.5194/acp-18-6259-2018.

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Abstract. The absorption Ångström exponent (AAE) is an important aerosol optical parameter used for aerosol characterization and apportionment studies. The AAE of black carbon (BC) particles is widely accepted to be 1.0, although observational estimates give quite a wide range of 0.6–1.3. With considerable uncertainties related to observations, a numerical study is a powerful method, if not the only one, to provide a better and more accurate understanding on BC AAE. This study calculates BC AAE using realistic particle geometries based on fractal aggregate and an accurate numerical optical mod

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18

Saleh, R., C. J. Hennigan, G. R. McMeeking, et al. "Absorptivity of brown carbon in fresh and photo-chemically aged biomass-burning emissions." Atmospheric Chemistry and Physics Discussions 13, no. 5 (2013): 11509–36. http://dx.doi.org/10.5194/acpd-13-11509-2013.

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Abstract. Experiments were conducted to investigate light absorption of organic aerosol (OA) in fresh and photo-chemically aged biomass-burning emissions. The experiments considered residential hardwood fuel (oak) and fuels commonly consumed in wild-land and prescribed fires in the United States (pocosin pine and gallberry). Photo-chemical aging was performed in an environmental chamber. We constrained the light-absorption properties of the OA using conservative limiting assumptions, and found that both primary organic aerosol (POA) in the fresh emissions and secondary organic aerosol (SOA) pr

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19

Schuster, G. L., O. Dubovik, A. Arola, T. F. Eck, and B. N. Holben. "Remote sensing of soot carbon – Part 2: Understanding the absorption Ångström exponent." Atmospheric Chemistry and Physics 16, no. 3 (2016): 1587–602. http://dx.doi.org/10.5194/acp-16-1587-2016.

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Abstract. Recently, some authors have suggested that the absorption Ångström exponent (AAE) can be used to deduce the component aerosol absorption optical depths (AAODs) of carbonaceous aerosols in the AERONET database. This AAE approach presumes that AAE ≪ 1 for soot carbon, which contrasts the traditional small particle limit of AAE = 1 for soot carbon. Thus, we provide an overview of the AERONET retrieval, and we investigate how the microphysics of carbonaceous aerosols can be interpreted in the AERONET AAE product. We find that AAE ≪ 1 in the AERONET database requires large coarse mode fra

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20

Lack, D. A., and J. M. Langridge. "On the attribution of black and brown carbon light absorption using the Ångström exponent." Atmospheric Chemistry and Physics 13, no. 20 (2013): 10535–43. http://dx.doi.org/10.5194/acp-13-10535-2013.

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Abstract. The absorption Ångström exponent (AAE) of externally mixed black carbon (BCExt), or BC internally mixed with non-absorbing material (BCInt), is often used to determine the contribution of brown carbon (BrC) light absorption at short visible wavelengths. This attribution method contains assumptions with uncertainties that have not been formally assessed. We show that the potential range of AAE for BCExt (or BCInt) in the atmosphere can reasonably lead to +7% to −22% uncertainty in BCExt (or BCInt) absorption at short wavelengths derived from measurements made at longer wavelengths, wh

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21

Lack, D. A., and J. M. Langridge. "On the attribution of black and brown carbon light absorption using the Ångström exponent." Atmospheric Chemistry and Physics Discussions 13, no. 6 (2013): 15493–515. http://dx.doi.org/10.5194/acpd-13-15493-2013.

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Abstract. The absorption Ångström exponent (åAbs) of black carbon (BC), or BC internally mixed with non-absorbing material (BCInt), is often used to differentiate the contribution of black carbon, dust and brown carbon to light absorption at low-visible wavelengths. This attribution method contains assumptions with uncertainties that have not been formally assessed. We show that the potential range of åAbs for BC (or BCInt) in the atmosphere can reasonably lead to +7% to −22% uncertainty in BC (or BCInt) absorption at 404nm derived from measurements made at 658 nm. These uncertainties propagat

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22

Cheng, Yuan, Zheng Kong, Jiheng Yu, and Liang Mei. "Measurements of the single-wavelength aerosol Ångström exponent based on differential absorption." Optics & Laser Technology 184 (June 2025): 112437. https://doi.org/10.1016/j.optlastec.2025.112437.

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23

Zhao, Dapeng, Yan Yin, Chao Liu, Chunsong Lu, and Xiaofeng Xu. "Can the Aerosol Absorption Ångström Exponent Represent Aerosol Color in the Atmosphere: A Numerical Study." Atmosphere 11, no. 2 (2020): 187. http://dx.doi.org/10.3390/atmos11020187.

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The aerosol absorption Ångström exponent (AAE) is widely used to indicate aerosol absorption spectrum variations and is an important parameter for characterizing aerosol optical absorption properties. This study discusses the relationship between aerosol AAEs and their colors numerically. By combining light scattering simulations, a two-stream radiative transfer model, and an RGB (Red, Green, and Blue) color model, aerosol colors that can be sensed by human eyes are numerically generated with both the solar spectrum and human eye response taken into account. Our results indicate that the respo

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24

Andrews, E., P. J. Sheridan, and J. A. Ogren. "Seasonal differences in the vertical profiles of aerosol optical properties over rural Oklahoma." Atmospheric Chemistry and Physics 11, no. 20 (2011): 10661–76. http://dx.doi.org/10.5194/acp-11-10661-2011.

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Abstract. A small airplane made 597 aerosol optical property (light absorption and light scattering) vertical profile measurements over a rural Oklahoma site between March 2000 and December 2007. The aerosol profiles obtained during these 8 yr of measurements suggest significant seasonal differences in aerosol loading (scattering and absorption). The highest amounts of scattering and absorbing aerosol are observed during the summer and the lowest loading occurs during the winter. The relative contribution of aerosol absorption is highest in the winter (i.e., single scattering albedo is lowest

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Rennie, Megan, Vera Samburova, Deep Sengupta, et al. "Emissions from the Open Laboratory Combustion of Cheatgrass (Bromus Tectorum)." Atmosphere 11, no. 4 (2020): 406. http://dx.doi.org/10.3390/atmos11040406.

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Cheatgrass (Bromus Tectorum) is a highly invasive species in the Great Basin of the Western USA that is increasing the frequency and intensity of wildland fires. Though cheatgrass plays a significant role in the fire ecology of the Great Basin, very little is known about its combustion emissions. The fresh smoke from 16 open laboratory burns of cheatgrass was analyzed using real-time measurements and filter analysis. We presented measured intensive optical properties of the emitted smoke, including absorption Ångström exponent (AAE), scattering Ångström exponent (SAE), single scattering albedo

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26

Linke, Claudia, Inas Ibrahim, Nina Schleicher, et al. "A novel single-cavity three-wavelength photoacoustic spectrometer for atmospheric aerosol research." Atmospheric Measurement Techniques 9, no. 11 (2016): 5331–46. http://dx.doi.org/10.5194/amt-9-5331-2016.

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Abstract. The spectral light-absorbing behavior of carbonaceous aerosols varies depending on the chemical composition and structure of the particles. A new single-cavity three-wavelength photoacoustic spectrometer was developed and characterized for measuring absorption coefficients at three wavelengths across the visible spectral range. In laboratory studies, several types of soot with different organic content were generated by a diffusion flame burner and were investigated for changes in mass-specific absorption cross section (MAC) values, absorption and scattering Ångström exponents (αabs

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Vijay, Saloni, Lars Schöbitz, Hope Kelvin Chilunga, and Elizabeth Tilley. "Absorption Ångström Exponent Values to Identify Light-absorbing Carbonaceous Aerosol Sources in Blantyre, Malawi." Aerosol and Air Quality Research 24 (2024): 240095. http://dx.doi.org/10.4209/aaqr.240095.

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Drinovec, Luka, Uroš Jagodič, Luka Pirker, et al. "A dual-wavelength photothermal aerosol absorption monitor: design, calibration and performance." Atmospheric Measurement Techniques 15, no. 12 (2022): 3805–25. http://dx.doi.org/10.5194/amt-15-3805-2022.

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Abstract. There exists a lack of aerosol absorption measurement techniques with low uncertainties and without artefacts. We have developed the two-wavelength Photothermal Aerosol Absorption Monitor (PTAAM-2λ), which measures the aerosol absorption coefficient at 532 and 1064 nm. Here we describe its design, calibration and mode of operation and evaluate its applicability, limits and uncertainties. The 532 nm channel was calibrated with ∼ 1 µmol mol−1 NO2, whereas the 1064 nm channel was calibrated using measured size distribution spectra of nigrosin particles and a Mie calculation. Since the a

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Gyawali, M., W. P. Arnott, R. A. Zaveri, et al. "Photoacoustic optical properties at UV, VIS, and near IR wavelengths for laboratory generated and winter time ambient urban aerosols." Atmospheric Chemistry and Physics 12, no. 5 (2012): 2587–601. http://dx.doi.org/10.5194/acp-12-2587-2012.

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Abstract. We present the laboratory and ambient photoacoustic (PA) measurement of aerosol light absorption coefficients at ultraviolet wavelength (i.e., 355 nm) and compare with measurements at 405, 532, 870, and 1047 nm. Simultaneous measurements of aerosol light scattering coefficients were achieved by the integrating reciprocal nephelometer within the PA's acoustic resonator. Absorption and scattering measurements were carried out for various laboratory-generated aerosols, including salt, incense, and kerosene soot to evaluate the instrument calibration and gain insight on the spectral depe

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Virkkula, Aki. "Modeled source apportionment of black carbon particles coated with a light-scattering shell." Atmospheric Measurement Techniques 14, no. 5 (2021): 3707–19. http://dx.doi.org/10.5194/amt-14-3707-2021.

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Abstract. The Aethalometer model has been used widely for estimating the contributions of fossil fuel emissions and biomass burning to equivalent black carbon (eBC). The calculation is based on measured absorption Ångström exponents (αabs). The interpretation of αabs is ambiguous since it is well known that it not only depends on the dominant absorber but also on the size and internal structure of the particles, core size, and shell thickness. In this work the uncertainties of the Aethalometer-model-derived apparent fractions of absorption by eBC from fossil fuel and biomass burning are evalua

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Montilla, E., S. Mogo, V. Cachorro, J. Lopez, and A. de Frutos. "Absorption, scattering and single scattering albedo of aerosols obtained from in situ measurements in the subarctic coastal region of Norway." Atmospheric Chemistry and Physics Discussions 11, no. 1 (2011): 2161–82. http://dx.doi.org/10.5194/acpd-11-2161-2011.

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Abstract. In situ measurements of aerosol optical properties were made in summer 2008 at the ALOMAR station facility (69°16 N, 16°00 E), located at a rural site in the North of the island of Andøya (Vesterålen archipelago), about 300 km north of the Arctic Circle. The extended three months campaign was part of the POLAR-CAT Project of the International Polar Year (IPY-2007-2008), and its goal was to characterize the aerosols of this sub-Arctic area which frequently transporte to the Arctic region. The ambient light-scattering coefficient, σs(550 nm), at ALOMAR had a hourly mean value of 5.412

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Tian, Ping, Dantong Liu, Delong Zhao, et al. "In situ vertical characteristics of optical properties and heating rates of aerosol over Beijing." Atmospheric Chemistry and Physics 20, no. 4 (2020): 2603–22. http://dx.doi.org/10.5194/acp-20-2603-2020.

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Abstract. Characterizing vertical profiles of aerosol optical properties is important because relying on only the surface or column-integrated measurements cannot unambiguously constrain the radiative impacts of aerosol. This study presents series of vertical profiles of in situ measured multi-wavelength optical properties of aerosols during three pollution events from November to December 2016 over the Beijing region. For all pollution events, the clean periods (CPs) before pollution initialization showed a higher scattering Ångström exponent (SAE) and a smaller asymmetry parameter (g) with r

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Chen, Cheng, Oleg Dubovik, Daven K. Henze, et al. "Constraining global aerosol emissions using POLDER/PARASOL satellite remote sensing observations." Atmospheric Chemistry and Physics 19, no. 23 (2019): 14585–606. http://dx.doi.org/10.5194/acp-19-14585-2019.

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Abstract. We invert global black carbon (BC), organic carbon (OC) and desert dust (DD) aerosol emissions from POLDER/PARASOL spectral aerosol optical depth (AOD) and aerosol absorption optical depth (AAOD) using the GEOS-Chem inverse modeling framework. Our inverse modeling framework uses standard a priori emissions to provide a posteriori emissions that are constrained by POLDER/PARASOL AODs and AAODs. The following global emission values were retrieved for the three aerosol components: 18.4 Tg yr−1 for BC, 109.9 Tg yr−1 for OC and 731.6 Tg yr−1 for DD for the year 2010. These values show a d

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Cazorla, A., R. Bahadur, K. J. Suski, et al. "Relating aerosol absorption due to soot, organic carbon, and dust to emission sources determined from in-situ chemical measurements." Atmospheric Chemistry and Physics Discussions 13, no. 2 (2013): 3451–83. http://dx.doi.org/10.5194/acpd-13-3451-2013.

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Abstract. Estimating the aerosol contribution to the global or regional radiative forcing can take advantage of the relationship between the spectral aerosol optical properties and the size and chemical composition of aerosol. Long term global optical measurements from observational networks or satellites can be used in such studies. Using in-situ chemical mixing state measurements can help us to constrain the limitations of such estimates. In this study, the Absorption Ångström Exponent (AAE) and the Scattering Ångström Exponent (SAE) derived from 10 operational AERONET sites in California ar

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Cazorla, A., R. Bahadur, K. J. Suski, et al. "Relating aerosol absorption due to soot, organic carbon, and dust to emission sources determined from in-situ chemical measurements." Atmospheric Chemistry and Physics 13, no. 18 (2013): 9337–50. http://dx.doi.org/10.5194/acp-13-9337-2013.

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Abstract. Estimating the aerosol contribution to the global or regional radiative forcing can take advantage of the relationship between the spectral aerosol optical properties and the size and chemical composition of aerosol. Long term global optical measurements from observational networks or satellites can be used in such studies. Using in-situ chemical mixing state measurements can help us to constrain the limitations of such estimates. In this study, the Absorption Ångström Exponent (AAE) and the Scattering Ångström Exponent (SAE) derived from 10 operational AERONET sites in California ar

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Doherty, Sarah J., Pablo E. Saide, Paquita Zuidema, et al. "Modeled and observed properties related to the direct aerosol radiative effect of biomass burning aerosol over the southeastern Atlantic." Atmospheric Chemistry and Physics 22, no. 1 (2022): 1–46. http://dx.doi.org/10.5194/acp-22-1-2022.

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Abstract. Biomass burning smoke is advected over the southeastern Atlantic Ocean between July and October of each year. This smoke plume overlies and mixes into a region of persistent low marine clouds. Model calculations of climate forcing by this plume vary significantly in both magnitude and sign. NASA EVS-2 (Earth Venture Suborbital-2) ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) had deployments for field campaigns off the west coast of Africa in 3 consecutive years (September 2016, August 2017, and October 2018) with the goal of better characterizing this plume a

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Gyawali, M., W. P. Arnott, R. A. Zaveri, et al. "Photoacoustic optical properties at UV, VIS, and near IR wavelengths for laboratory generated and winter time ambient urban aerosols." Atmospheric Chemistry and Physics Discussions 11, no. 9 (2011): 25063–98. http://dx.doi.org/10.5194/acpd-11-25063-2011.

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Abstract. We present the first laboratory and ambient photoacoustic (PA) measurement of aerosol light absorption coefficients at ultraviolet (UV) wavelength (i.e. 355 nm) and compare with measurements at 405, 532, 870, and 1047 nm. Simultaneous measurements of aerosol light scattering coefficients were achieved by the integrating reciprocal nephelometer within the PA's acoustic resonator. Absorption and scattering measurements were carried out for various laboratory-generated aerosols, including salt, incense, and kerosene soot to evaluate the instrument calibration and gain insight on the spe

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Sinyuk, Alexander, Brent N. Holben, Thomas F. Eck, et al. "Employing relaxed smoothness constraints on imaginary part of refractive index in AERONET aerosol retrieval algorithm." Atmospheric Measurement Techniques 15, no. 14 (2022): 4135–51. http://dx.doi.org/10.5194/amt-15-4135-2022.

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Abstract. In the Aerosol Robotic Network (AERONET) retrieval algorithm, smoothness constraints on the imaginary part of the refractive index provide control of retrieved spectral dependence of aerosol absorption by preventing the inversion code from fitting the noise in optical measurements and thus avoiding unrealistic oscillations of retrievals with wavelength. The history of implementation of the smoothness constraints in the AERONET retrieval algorithm is discussed. It is shown that the latest version of the smoothness constraints on the imaginary part of refractive index, termed standard

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Giannakaki, E., D. S. Balis, V. Amiridis, and C. Zerefos. "Optical properties of different aerosol types: seven years of combined Raman-elastic backscatter lidar measurements in Thessaloniki, Greece." Atmospheric Measurement Techniques 3, no. 3 (2010): 569–78. http://dx.doi.org/10.5194/amt-3-569-2010.

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Abstract. We present our combined Raman/elastic backscatter lidar observations which were carried out at the EARLINET station of Thessaloniki, Greece, during the period 2001–2007. The largest optical depths are observed for Saharan dust and smoke aerosol particles. For local and continental polluted aerosols the measurements indicate high aerosol loads. However, measurements associated with the local path indicate enhanced aerosol load within the Planetary Boundary Layer. The lowest value of aerosol optical depth is observed for continental aerosols, from West directions with less free troposp

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Garland, R. M., H. Yang, O. Schmid, et al. "Aerosol optical properties in a rural environment near the mega-city Guangzhou, China: implications for regional air pollution and radiative forcing." Atmospheric Chemistry and Physics Discussions 8, no. 2 (2008): 6845–901. http://dx.doi.org/10.5194/acpd-8-6845-2008.

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Abstract. The scattering and absorption of solar radiation by atmospheric aerosols is a key element of the Earth's radiative energy balance and climate. The optical properties of aerosol particles are, however, highly variable and not well characterized, especially near newly emerging mega-cities. In this study, aerosol optical properties were measured at a regional background site approximately 60 km northwest of the mega-city Guangzhou in southeast China. The measurements were part of the "Program of Regional Integrated Experiments of Air Quality over the Pearl River Delta" intensive campaig

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Li, J., B. E. Carlson, O. Dubovik, and A. A. Lacis. "Recent trends in aerosol optical properties derived from AERONET measurements." Atmospheric Chemistry and Physics Discussions 14, no. 10 (2014): 14351–97. http://dx.doi.org/10.5194/acpd-14-14351-2014.

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Abstract. The Aerosol Robotic Network (AERONET) has been providing high-quality retrievals of aerosol optical properties from the surface at worldwide locations for more than a decade. Many sites have continuous and consistent records for more than 10 years, which enables the investigation of long-term trends of aerosol properties at these locations. In this study, we present trend analysis of AERONET data at 63 selected locations. In addition to commonly studied parameters such as Aerosol Optical Depth (AOD) and Ångström Exponent (AE), we also focus on Absorption Aerosol Optical Depth (ABS),

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Isolabella, Tommaso, Vera Bernardoni, Alessandro Bigi, et al. "A new software toolkit for optical apportionment of carbonaceous aerosol." Atmospheric Measurement Techniques 17, no. 4 (2024): 1363–73. http://dx.doi.org/10.5194/amt-17-1363-2024.

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Abstract. Instruments measuring aerosol light absorption, such as the Aethalometer and the Multi-Wavelength Absorbance Analyzer (MWAA), have been extensively used to characterize optical absorption of atmospheric particulate matter. Data retrieved with such instruments can be analysed with mathematical models to apportion different aerosol sources (Aethalometer model) and components (MWAA model). In this work we present an upgrade to the MWAA optical apportionment model. In addition to the apportionment of the absorption coefficient babs in its components (black carbon and brown carbon) and so

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Ealo, Marina, Andrés Alastuey, Anna Ripoll, et al. "Detection of Saharan dust and biomass burning events using near-real-time intensive aerosol optical properties in the north-western Mediterranean." Atmospheric Chemistry and Physics 16, no. 19 (2016): 12567–86. http://dx.doi.org/10.5194/acp-16-12567-2016.

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Abstract. The study of Saharan dust events (SDEs) and biomass burning (BB) emissions are both topics of great scientific interest since they are frequent and important polluting scenarios affecting air quality and climate. The main aim of this work is evaluating the feasibility of using near-real-time in situ aerosol optical measurements for the detection of these atmospheric events in the western Mediterranean Basin (WMB). With this aim, intensive aerosol optical properties (SAE: scattering Ångström exponent, AAE: absorption Ångström exponent, SSAAE: single scattering albedo Ångström exponent

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Giannakaki, E., D. S. Balis, V. Amiridis, and C. Zerefos. "Optical properties of different aerosol types: seven years of combined Raman- elastic backscatter lidar measurements in Thessaloniki, Greece." Atmospheric Measurement Techniques Discussions 2, no. 6 (2009): 3027–54. http://dx.doi.org/10.5194/amtd-2-3027-2009.

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Abstract. We present our combined Raman/elastic backscatter lidar observations which were carried out at the EARLINET station of Thessaloniki, Greece, during the period 2001–2007. The largest optical depths are observed for Saharan dust and smoke aerosol loads. For "local" and "continental polluted" aerosols the measurements indicate moderate aerosol loads. However, measurements associated with the "local" path show lower values of free tropospheric contribution (37% versus 46% for "continental polluted") and thus, enhanced aerosol load within the Planetary Boundary Layer. The lowest value of

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Török, Sandra, Vilhelm B. Malmborg, Johan Simonsson, et al. "Investigation of the absorption Ångström exponent and its relation to physicochemical properties for mini-CAST soot." Aerosol Science and Technology 52, no. 7 (2018): 757–67. http://dx.doi.org/10.1080/02786826.2018.1457767.

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Backman, J., A. Virkkula, V. Vakkari, et al. "Differences in aerosol absorption Ångström exponents between correction algorithms for particle soot absorption photometer measured on South African Highveld." Atmospheric Measurement Techniques Discussions 7, no. 9 (2014): 9733–69. http://dx.doi.org/10.5194/amtd-7-9733-2014.

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Abstract. Absorption Ångstrom exponents (AAE) calculated from filter-based absorption measurements are often used to give information on the origin of the ambient aerosol, for example to distinguish between urban pollution and biomass burning aerosol. Filter-based absorption measurements are a widely used method and are commonly used at aerosol monitoring stations globally. Several correction algorithms are used to account for the artifacts associated with filter-based absorption techniques. These algorithms are of profound importance when determining the absolute amount of absorption by the a

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Luoma, Krista, Aki Virkkula, Pasi Aalto, Katrianne Lehtipalo, Tuukka Petäjä, and Markku Kulmala. "Effects of different correction algorithms on absorption coefficient – a comparison of three optical absorption photometers at a boreal forest site." Atmospheric Measurement Techniques 14, no. 10 (2021): 6419–41. http://dx.doi.org/10.5194/amt-14-6419-2021.

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Abstract. We present a comparison between three absorption photometers that measured the absorption coefficient (σabs) of ambient aerosol particles in 2012–2017 at SMEAR II (Station for Measuring Ecosystem–Atmosphere Relations II), a measurement station located in a boreal forest in southern Finland. The comparison included an Aethalometer (AE31), a multi-angle absorption photometer (MAAP), and a particle soot absorption photometer (PSAP). These optical instruments measured particles collected on a filter, which is a source of systematic errors, since in addition to the particles, the filter f

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Pandolfi, M., A. Ripoll, X. Querol, and A. Alastuey. "Climatology of aerosol optical properties and black carbon mass absorption cross section at a remote high altitude site in the Western Mediterranean Basin." Atmospheric Chemistry and Physics Discussions 14, no. 3 (2014): 3777–814. http://dx.doi.org/10.5194/acpd-14-3777-2014.

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Abstract. Aerosol light scattering, backscattering and absorption were measured at Montsec (MSC; 42°3' N, 0°44' E, 1570 m a.s.l.), a remote high-altitude site in the Western Mediterranean Basin. Mean (± sd) scattering, hemispheric backscattering and absorption were 18.9 ± 20.8 Mm−1, 2.6 ± 2.8 Mm−1 and 1.5 ± 1.4 Mm−1, respectively at 635 nm during the period under study (June 2011–June 2013). Mean values of single scattering albedo (635 nm), scattering Ångström exponent (450–635 nm), backscatter-to-scatter ratio (635 nm), asymmetry parameter (635 nm) and black carbon mass absorption cross secti

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Drinovec, Luka, Asta Gregorič, Peter Zotter, et al. "The filter-loading effect by ambient aerosols in filter absorption photometers depends on the coating of the sampled particles." Atmospheric Measurement Techniques 10, no. 3 (2017): 1043–59. http://dx.doi.org/10.5194/amt-10-1043-2017.

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Abstract. Black carbon is a primary aerosol tracer for high-temperature combustion emissions and can be used to characterize the time evolution of its sources. It is correlated with a decrease in public health and contributes to atmospheric warming. Black carbon measurements are usually conducted with absorption filter photometers, which are prone to several artifacts, including the filter-loading effect – a saturation of the instrumental response due to the accumulation of the sample in the filter matrix. In this paper, we investigate the hypothesis that this filter-loading effect depends on

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Li, Zhujie, Haobo Tan, Jun Zheng, et al. "Light absorption properties and potential sources of particulate brown carbon in the Pearl River Delta region of China." Atmospheric Chemistry and Physics 19, no. 18 (2019): 11669–85. http://dx.doi.org/10.5194/acp-19-11669-2019.

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Abstract. Brown carbon (BrC) is a special type of organic aerosol (OA), capable of absorbing solar radiation from near-ultraviolet (UV) to visible wavelengths, which may lead to an increased aerosol radiative effect in the atmosphere. While high concentrations of OAs have been observed in the Pearl River Delta (PRD) region of China, the optical properties and corresponding radiative forcing of BrC in the PRD are still not well understood. In this work, we conducted a set of comprehensive measurements of atmospheric particulate matter from 29 November 2014 to 2 January 2015 to investigate aeros

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