Pohorsky, R., Baccarini, A., Brett, N. et al. (14 more authors) (2025) In situ vertical observations of the layered structure of air pollution in a continental high-latitude urban boundary layer during winter. Atmospheric Chemistry and Physics, 25 (6). pp. 3687-3715. ISSN: 1680-7316
Abstract
Vertical in situ measurements of aerosols and trace gases were conducted in Fairbanks, Alaska, during winter 2022 as part of the Alaskan Layered Pollution and Chemical Analysis campaign (ALPACA). Using a tethered balloon, the study explores the dispersion of pollutants in the continental high-latitude stable boundary layer (SBL). Analysis of 24 flights revealed a stratified SBL structure with different pollution layers in the lowest tens of meters of the atmosphere, offering unprecedented detail. Surface emissions generally accumulated in a surface mixing layer (ML) extending to an average of 51 m, with a well-mixed sublayer (MsL) reaching 22 m. The height and concentrations within the ML were strongly influenced by a local wind driven by nearby topography under anticyclonic conditions. During strong radiative cooling, a drainage flow increased turbulence near the surface, altering the temperature profile and deepening the ML. Above the ML, pollution concentrations decreased but showed clear signs of freshly released anthropogenic emissions. Higher in the atmosphere, above elevated inversions, pollution levels were similar to previously reported Arctic haze concentrations, even though Fairbanks' outflow concentrations below elevated inversions were up to 6 times higher, likely due to power plant emissions. In situ measurements indicated that gas and particle tracer ratios in elevated power plant plumes differed significantly from those near the surface. Overall, pollution layers were strongly correlated with the temperature stratification and emission heights, emphasizing the need for improved representation of temperature inversions and emission sources in air quality models to enhance pollution forecasts.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © Author(s) 2025. This is an open access article under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) |
Date Deposited: | 02 Oct 2025 11:44 |
Last Modified: | 02 Oct 2025 11:44 |
Status: | Published |
Publisher: | Copernicus Publications |
Identification Number: | 10.5194/acp-25-3687-2025 |
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Sustainable Development Goals: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:232129 |