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A European aerosol phenomenology - 6 : Scattering properties of atmospheric aerosol particles from 28 ACTRIS sites

Pandolfi, Marco; Alados-Arboledas, Lucas; Alastuey, Andrés; Andrade, Marcos; Angelov, Christo; Artiñano, Begoña; Backman, John; Baltensperger, Urs; Bonasoni, Paolo and Bukowiecki, Nicolas, et al. (2018) In Atmospheric Chemistry and Physics 18(11). p.7877-7911
Abstract

This paper presents the light-scattering properties of atmospheric aerosol particles measured over the past decade at 28 ACTRIS observatories, which are located mainly in Europe. The data include particle light scattering (σsp) and hemispheric backscattering (σbsp) coefficients, scattering Ångström exponent (SAE), backscatter fraction (BF) and asymmetry parameter (g). An increasing gradient of σsp is observed when moving from remote environments (arctic/mountain) to regional and to urban environments. At a regional level in Europe, σsp also increases when moving from Nordic and Baltic countries and from western Europe to central/eastern Europe, whereas no clear spatial gradient is observed for other... (More)

This paper presents the light-scattering properties of atmospheric aerosol particles measured over the past decade at 28 ACTRIS observatories, which are located mainly in Europe. The data include particle light scattering (σsp) and hemispheric backscattering (σbsp) coefficients, scattering Ångström exponent (SAE), backscatter fraction (BF) and asymmetry parameter (g). An increasing gradient of σsp is observed when moving from remote environments (arctic/mountain) to regional and to urban environments. At a regional level in Europe, σsp also increases when moving from Nordic and Baltic countries and from western Europe to central/eastern Europe, whereas no clear spatial gradient is observed for other station environments. The SAE does not show a clear gradient as a function of the placement of the station. However, a west-to-east-increasing gradient is observed for both regional and mountain placements, suggesting a lower fraction of fine-mode particle in western/south-western Europe compared to central and eastern Europe, where the fine-mode particles dominate the scattering. The g does not show any clear gradient by station placement or geographical location reflecting the complex relationship of this parameter with the physical properties of the aerosol particles. Both the station placement and the geographical location are important factors affecting the intraannual variability. At mountain sites, higher σsp and SAE values are measured in the summer due to the enhanced boundary layer influence and/or new particle-formation episodes. Conversely, the lower horizontal and vertical dispersion during winter leads to higher σsp values at all low-altitude sites in central and eastern Europe compared to summer. These sites also show SAE maxima in the summer (with corresponding g minima). At all sites, both SAE and g show a strong variation with aerosol particle loading. The lowest values of g are always observed together with low σsp values, indicating a larger contribution from particles in the smaller accumulation mode. During periods of high σsp values, the variation of g is less pronounced, whereas the SAE increases or decreases, suggesting changes mostly in the coarse aerosol particle mode rather than in the fine mode. Statistically significant decreasing trends of σsp are observed at 5 out of the 13 stations included in the trend analyses. The total reductions of σsp are consistent with those reported for PM2.5 and PM10 mass concentrations over similar periods across Europe.

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Atmospheric Chemistry and Physics
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18
issue
11
pages
35 pages
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Copernicus Gesellschaft Mbh
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  • scopus:85048229461
ISSN
1680-7316
DOI
10.5194/acp-18-7877-2018
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English
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c048abc1-e32d-4eb7-865c-84482831204b
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2018-06-20 16:31:28
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@article{c048abc1-e32d-4eb7-865c-84482831204b,
  abstract     = {<p>This paper presents the light-scattering properties of atmospheric aerosol particles measured over the past decade at 28 ACTRIS observatories, which are located mainly in Europe. The data include particle light scattering (σ<sub>sp</sub>) and hemispheric backscattering (σ<sub>bsp</sub>) coefficients, scattering Ångström exponent (SAE), backscatter fraction (BF) and asymmetry parameter (g). An increasing gradient of σsp is observed when moving from remote environments (arctic/mountain) to regional and to urban environments. At a regional level in Europe, σ<sub>sp</sub> also increases when moving from Nordic and Baltic countries and from western Europe to central/eastern Europe, whereas no clear spatial gradient is observed for other station environments. The SAE does not show a clear gradient as a function of the placement of the station. However, a west-to-east-increasing gradient is observed for both regional and mountain placements, suggesting a lower fraction of fine-mode particle in western/south-western Europe compared to central and eastern Europe, where the fine-mode particles dominate the scattering. The g does not show any clear gradient by station placement or geographical location reflecting the complex relationship of this parameter with the physical properties of the aerosol particles. Both the station placement and the geographical location are important factors affecting the intraannual variability. At mountain sites, higher σ<sub>sp</sub> and SAE values are measured in the summer due to the enhanced boundary layer influence and/or new particle-formation episodes. Conversely, the lower horizontal and vertical dispersion during winter leads to higher σ<sub>sp</sub> values at all low-altitude sites in central and eastern Europe compared to summer. These sites also show SAE maxima in the summer (with corresponding g minima). At all sites, both SAE and g show a strong variation with aerosol particle loading. The lowest values of g are always observed together with low σ<sub>sp</sub> values, indicating a larger contribution from particles in the smaller accumulation mode. During periods of high σ<sub>sp</sub> values, the variation of g is less pronounced, whereas the SAE increases or decreases, suggesting changes mostly in the coarse aerosol particle mode rather than in the fine mode. Statistically significant decreasing trends of σ<sub>sp</sub> are observed at 5 out of the 13 stations included in the trend analyses. The total reductions of σ<sub>sp</sub> are consistent with those reported for PM<sub>2.5</sub> and PM<sub>10</sub> mass concentrations over similar periods across Europe.</p>},
  author       = {Pandolfi, Marco and Alados-Arboledas, Lucas and Alastuey, Andrés and Andrade, Marcos and Angelov, Christo and Artiñano, Begoña and Backman, John and Baltensperger, Urs and Bonasoni, Paolo and Bukowiecki, Nicolas and Collaud Coen, Martine and Conil, Sébastien and Coz, Esther and Crenn, Vincent and Dudoitis, Vadimas and Ealo, Marina and Eleftheriadis, Kostas and Favez, Olivier and Fetfatzis, Prodromos and Fiebig, Markus and Flentje, Harald and Ginot, Patrick and Gysel, Martin and Henzing, Bas and Hoffer, Andras and Holubova Smejkalova, Adela and Kalapov, Ivo and Kalivitis, Nikos and Kouvarakis, Giorgos and Kristensson, Adam and Kulmala, Markku and Lihavainen, Heikki and Lunder, Chris and Luoma, Krista and Lyamani, Hassan and Marinoni, Angela and Mihalopoulos, Nikos and Moerman, Marcel and Nicolas, José and O'Dowd, Colin and Petäjä, Tuukka and Petit, Jean Eudes and Marc Pichon, Jean and Prokopciuk, Nina and Putaud, Jean Philippe and Rodríguez, Sergio and Sciare, Jean and Sellegri, Karine and Swietlicki, Erik and Titos, Gloria and Tuch, Thomas and Tunved, Peter and Ulevicius, Vidmantas and Vaishya, Aditya and Vana, Milan and Virkkula, Aki and Vratolis, Stergios and Weingartner, Ernest and Wiedensohler, Alfred and Laj, Paolo},
  issn         = {1680-7316},
  language     = {eng},
  month        = {06},
  number       = {11},
  pages        = {7877--7911},
  publisher    = {Copernicus Gesellschaft Mbh},
  series       = {Atmospheric Chemistry and Physics},
  title        = {A European aerosol phenomenology - 6 : Scattering properties of atmospheric aerosol particles from 28 ACTRIS sites},
  url          = {http://dx.doi.org/10.5194/acp-18-7877-2018},
  volume       = {18},
  year         = {2018},
}