Urban-to-downwind variations in aerosol composition and optical properties in the Paris urban plume from coordinated airborne and ground-based observations
- 1Université Paris Cité (Paris, France)
- 2Université Paris-Est Créteil (Créteil, France)
- 3Centre National de la Recherche Scientifique (Paris, France)
Abstract
Aerosols play a critical role in Earth's climate, yet changes in their physicochemical properties during atmospheric transport remain an important source of uncertainty in predicting their climate impacts. Observational constraints on these changes over the first few hours of urban plume transport remain limited. Here, we investigated urban-to-downwind variations in aerosol physicochemical and optical properties using coordinated ground-based and airborne measurements in Paris and its downwind region, covering estimated plume transport times of ∼ 2–6 h. Urban plumes contributed modestly to downwind particle number concentrations in the 80–200 nm range and moderately enhanced submicron particulate matter (PM ₁ ) relative to the surrounding background. Organic aerosol (Org) dominated PM ₁ mass at both the urban site and downwind. Non-refractory PM ₁ component mass fractions and secondary aerosol mass relative to CO showed limited urban-to-downwind variations, whereas the relative contribution of more oxidized Org increased downwind. In contrast, optical properties exhibited pronounced differences, with higher plume-average single-scattering albedo at both 450 and 630 nm downwind. The complex refractive index shifted from lower real (∼ 1.35–1.40) and higher imaginary (∼ 0.03–0.08) components near the urban source to higher real (∼ 1.45–1.50) and lower imaginary (∼ 0.015–0.02) components downwind. The average absorption Ångström exponent was also higher downwind, indicating stronger wavelength dependence of aerosol absorption. These observations reveal systematic urban-to-downwind differences in aerosol physicochemical and optical properties consistent with atmospheric processing during transport. They highlight the importance of accounting for spatially evolving aerosol properties in atmospheric models and remote-sensing retrievals.
Versions
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BibTeX
@article{yu2026urbantodownwind,
title = {{Urban-to-downwind variations in aerosol composition and optical properties in the Paris urban plume from coordinated airborne and ground-based observations}},
author = {Chenjie Yu and Ludovico Di Antonio and Peter F. DeCarlo and Benjamin A. Nault and Alejandra Velazquez-Garcia and Eleonora Aruffo and Piero Di Carlo and Cyrielle Denjean and Sarah Tinorua and Thierry Bourrianne and Diana L. Pereira and Kevin Tu and Edouard Pangui and Mathieu Cazaunau and Astrid Bauville and Noël Grand and Antonin Bergé and Claudia Di Biagio and Aline Gratien and Matthias Beekmann and Guillaume Siour and Gilles Foret and Barbara D'Anna and Julien Kammer and Huihui Wu and Christopher Cantrell and Paola Formenti and Vincent Michoud},
journal = {Atmospheric Chemistry and Physics},
year = {2026},
month = oct,
doi = {10.5194/acp-26-15055-2026},
url = {https://doi.org/10.5194/acp-26-15055-2026},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Urban-to-downwind variations in aerosol composition and optical properties in the Paris urban plume from coordinated airborne and ground-based observations
AU - Chenjie Yu
AU - Ludovico Di Antonio
AU - Peter F. DeCarlo
AU - Benjamin A. Nault
AU - Alejandra Velazquez-Garcia
AU - Eleonora Aruffo
AU - Piero Di Carlo
AU - Cyrielle Denjean
AU - Sarah Tinorua
AU - Thierry Bourrianne
AU - Diana L. Pereira
AU - Kevin Tu
AU - Edouard Pangui
AU - Mathieu Cazaunau
AU - Astrid Bauville
AU - Noël Grand
AU - Antonin Bergé
AU - Claudia Di Biagio
AU - Aline Gratien
AU - Matthias Beekmann
AU - Guillaume Siour
AU - Gilles Foret
AU - Barbara D'Anna
AU - Julien Kammer
AU - Huihui Wu
AU - Christopher Cantrell
AU - Paola Formenti
AU - Vincent Michoud
PY - 2026
DA - 2026/10/27
JO - Atmospheric Chemistry and Physics
DO - 10.5194/acp-26-15055-2026
UR - https://doi.org/10.5194/acp-26-15055-2026
AB - Aerosols play a critical role in Earth's climate, yet changes in their physicochemical properties during atmospheric transport remain an important source of uncertainty in predicting their climate impacts. Observational constraints on these changes over the first few hours of urban plume transport remain limited. Here, we investigated urban-to-downwind variations in aerosol physicochemical and optical properties using coordinated ground-based and airborne measurements in Paris and its downwind region, covering estimated plume transport times of ∼ 2–6 h. Urban plumes contributed modestly to downwind particle number concentrations in the 80–200 nm range and moderately enhanced submicron particulate matter (PM ₁ ) relative to the surrounding background. Organic aerosol (Org) dominated PM ₁ mass at both the urban site and downwind. Non-refractory PM ₁ component mass fractions and secondary aerosol mass relative to CO showed limited urban-to-downwind variations, whereas the relative contribution of more oxidized Org increased downwind. In contrast, optical properties exhibited pronounced differences, with higher plume-average single-scattering albedo at both 450 and 630 nm downwind. The complex refractive index shifted from lower real (∼ 1.35–1.40) and higher imaginary (∼ 0.03–0.08) components near the urban source to higher real (∼ 1.45–1.50) and lower imaginary (∼ 0.015–0.02) components downwind. The average absorption Ångström exponent was also higher downwind, indicating stronger wavelength dependence of aerosol absorption. These observations reveal systematic urban-to-downwind differences in aerosol physicochemical and optical properties consistent with atmospheric processing during transport. They highlight the importance of accounting for spatially evolving aerosol properties in atmospheric models and remote-sensing retrievals.
SN - 1680-7324
ER -