In situ vertical observations of the layered structure of air pollution in a continental high-latitude urban boundary layer during winter
Year: 2025
Type: article
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 meters, with a well-mixed sub-layer (MsL) reaching 22 meters. The height and concentrations within the ML were strongly influenced by a local wind driven by nearby topography under anticyclonic conditions. Counterintuitively, 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 six 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.
Authors: Roman Pohorsky, Andrea Baccarini, Natalie Brett, Brice Barret, Slimane Bekki, Gianluca Pappaccogli, Elsa Dieudonné, Brice Temime-Roussel, Barbara D'Anna, Meeta Cesler-Maloney, Antonio Donateo, Stefano Decesari, Kathy S. Law, William R. Simpson, Javier Fochesatto, Steve R. Arnold, Julia Schmale
Institutions: École Polytechnique Fédérale de Lausanne, Centre National de la Recherche Scientifique, Université de Versailles Saint-Quentin-en-Yvelines, Sorbonne Université, Laboratoire atmosphères, milieux, observations spatiales, Université Toulouse III - Paul Sabatier, Laboratoire d'Aérologie, Université de Toulouse, Institute of Atmospheric Sciences and Climate, National Research Council, Université du littoral côte d'opale, Laboratoire de Physico-Chimie de l'Atmosphère, Aix-Marseille Université, University of Alaska Fairbanks, University of Leeds
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $1,725
Funders: National Science Foundation, Agence Nationale de la Recherche, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Centre National de la Recherche Scientifique, Institut Polaire Français Paul Emile Victor, Grand Équipement National De Calcul Intensif, International Arctic Science Committee, Swiss Polar Institute, National Oceanic and Atmospheric Administration, Natural Environment Research Council
Awards: Collaborative Research: NNA Track 1: Sustainably Navigating Arctic Pollution Through Engaging Communities (SNAP-TEC), AerosoL heterogeneous Processing as a source of oxidants in Cold winter Atmospheres: application to Alaska and UK (ALPACA-UK), Collaborative Research: Multi-phase Sulfur and Nitrogen Chemistry in Air and Snow during Alaskan Layered Pollution and Chemical Analysis (ALPACA), Climate-relevant aerosol sources and processes in the Arctic, G4300016217, G4444396473, G809195389, Vertical properties of aerosols in the Arctic lower atmosphere and their impact on cloud radiative effects
OpenAlex ID: W4408908963