According to the study, published in Atmospheric Chemistry and Physics, organic aerosol measured downwind of Paris was more oxidized than aerosol closer to the urban source. The optical properties of the particles also changed along the plume: aerosols showed a higher single-scattering albedo, higher real and lower imaginary refractive indices, and a stronger wavelength dependence of absorption downwind.

These shifts matter because aerosol composition and optical properties influence how particles scatter and absorb light, affecting climate forcing calculations and satellite and ground-based remote sensing. The findings highlight the need to represent evolving aerosol properties in atmospheric models and in remote-sensing retrievals, rather than assuming fixed values as air moves away from cities.

The research combined airborne and ground-based observations to capture the urban-to-downwind gradient directly, offering a detailed picture of how aging processes alter both the chemistry and the optical behavior of the Paris urban plume.

Subject of Research: Aerosol composition and optical property evolution in the Paris urban plume

Article Title: Urban-to-downwind variations in aerosol composition and optical properties in the Paris urban plume from coordinated airborne and ground-based observations

Article References: Yu, C., Di Antonio, L., DeCarlo, P. F., Nault, B. A., Velazquez-Garcia, A., Aruffo, E., Di Carlo, P., Denjean, C., Tinorua, S., Bourrianne, T., Pereira, D. L., Tu, K., Pangui, E., Cazaunau, M., Bauville, A., Grand, N., Bergé, A., Di Biagio, C., Gratien, A., … Michoud, V. (2026). Urban-to-downwind variations in aerosol composition and optical properties in the Paris urban plume from coordinated airborne and ground-based observations. Atmospheric Chemistry and Physics, 26(20), 15055-15079. https://doi.org/10.5194/acp-26-15055-2026

Image Credits: AI Generated

DOI: 10.5194/acp-26-15055-2026

Keywords: aerosols, Paris, urban plume, atmospheric chemistry, optical properties, organic aerosol, remote sensing, air quality, Atmospheric Chemistry and Physics, Urban-to-downwind, variations, aerosol