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Regional Transport in the Arctic: Sensitivity of NOx and Particulate Matter in Wintertime Urban Alaska to Background Air.

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Bibliographic Details
Title: Regional Transport in the Arctic: Sensitivity of NOx and Particulate Matter in Wintertime Urban Alaska to Background Air.
Authors: Hoffman, Alicia1 (AUTHOR) a.b.hoffman@leeds.ac.uk, Arnold, Steve R.1 (AUTHOR) s.arnold@leeds.ac.uk, Heard, Dwayne2 (AUTHOR), Whalley, Lisa2 (AUTHOR), Brett, Natalie1,3 (AUTHOR), Law, Kathy S.3 (AUTHOR), Raut, Jean‐Christophe3 (AUTHOR), Onishi, Tatsuo3 (AUTHOR), Bekki, Slimane3 (AUTHOR), Simpson, William R.4 (AUTHOR), Cesler‐Maloney, Meeta4 (AUTHOR), Barret, Brice5 (AUTHOR), Pohorsky, Roman6 (AUTHOR), Schmale, Julia6 (AUTHOR), Temime‐Roussel, Brice7 (AUTHOR), D'Anna, Barbara7 (AUTHOR)
Source: Journal of Geophysical Research. Atmospheres. 4/16/2026, Vol. 131 Issue 7, p1-20. 20p.
Subject Terms: *Particulate matter, *Air pollution, *Atmospheric ozone, *Air quality, *Atmospheric chemistry, *Cities & towns, Atmospheric transport
Geographic Terms: Fairbanks (Alaska), Arctic regions, Alaska
Abstract: Fairbanks, Alaska is an example of a subarctic city that experiences severe wintertime air quality episodes characterized by high concentrations of fine particulate matter (PM2.5) and nitrogen oxides (NO and NO2 = NOx). Previous research into these air quality episodes has focused on the impact of surface‐based inversions that trap local emissions. However, the availability of ozone is a limiting factor in local wintertime pollutant transformation, and sensitivity of Fairbanks air quality to ozone availability has not been investigated on a regional scale. Here, we assess the impact of regional transport on ozone, NOx, and particulate matter concentrations in Fairbanks, Alaska using three boundary conditions in the Community Multiscale Air Quality (CMAQ) model v5.4. We compared model results with measurements made during the ALPACA field campaign (model‐observation comparison), and we assessed the differences between pairs of models (model‐model comparison) using Euclidean distances of NO2, SO2, PM2.5, and O3. We find that modeling of NOx in the Fairbanks area depends on, amongst other factors, accurate boundary conditions of background ozone because NO + O3 titration is the dominant loss reaction of NO. PM2.5 in Fairbanks is affected by transport of existing background particulate matter rather than the transport of precursors. The boundary condition transport impacts metrics of air pollutants used for regulatory purposes throughout the model domain. Our results have important implications for accurate modeling of air quality in Arctic regions subject to strong local emissions and surface‐based inversions, and have implications for assessment of air quality attainment status. Plain Language Summary: Air quality in the subarctic city of Fairbanks, Alaska is often unhealthy during the winter due to extreme cold weather causing the trapping of local pollution close to breathing level. Despite the dominance of local emissions in degrading air quality, we show that atmospheric transport of ozone and particulate matter over long distances can affect air pollution in Fairbanks. We use different model representations of background air to understand how much Fairbanks air quality is impacted by regional transport. We show that modeled air quality in downtown Fairbanks is sensitive to abundances of background pollutants that can be transported into the city. This is due to the dominant atmospheric chemical reactions that occur in the extreme cold and dark conditions of Arctic winter which is sensitive to background ozone. These findings have implications for air quality attainment modeling. Key Points: Regional transport has a large impact on Fairbanks NOx due to dominant role of ozone titration in loss of NOPM2.5 is affected by regional transport of existing particulate matter, but not precursorsChemical boundary conditions produce significant model‐model differences, with implications for air quality attainment modeling [ABSTRACT FROM AUTHOR]
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Abstract:Fairbanks, Alaska is an example of a subarctic city that experiences severe wintertime air quality episodes characterized by high concentrations of fine particulate matter (PM2.5) and nitrogen oxides (NO and NO2 = NOx). Previous research into these air quality episodes has focused on the impact of surface‐based inversions that trap local emissions. However, the availability of ozone is a limiting factor in local wintertime pollutant transformation, and sensitivity of Fairbanks air quality to ozone availability has not been investigated on a regional scale. Here, we assess the impact of regional transport on ozone, NOx, and particulate matter concentrations in Fairbanks, Alaska using three boundary conditions in the Community Multiscale Air Quality (CMAQ) model v5.4. We compared model results with measurements made during the ALPACA field campaign (model‐observation comparison), and we assessed the differences between pairs of models (model‐model comparison) using Euclidean distances of NO2, SO2, PM2.5, and O3. We find that modeling of NOx in the Fairbanks area depends on, amongst other factors, accurate boundary conditions of background ozone because NO + O3 titration is the dominant loss reaction of NO. PM2.5 in Fairbanks is affected by transport of existing background particulate matter rather than the transport of precursors. The boundary condition transport impacts metrics of air pollutants used for regulatory purposes throughout the model domain. Our results have important implications for accurate modeling of air quality in Arctic regions subject to strong local emissions and surface‐based inversions, and have implications for assessment of air quality attainment status. Plain Language Summary: Air quality in the subarctic city of Fairbanks, Alaska is often unhealthy during the winter due to extreme cold weather causing the trapping of local pollution close to breathing level. Despite the dominance of local emissions in degrading air quality, we show that atmospheric transport of ozone and particulate matter over long distances can affect air pollution in Fairbanks. We use different model representations of background air to understand how much Fairbanks air quality is impacted by regional transport. We show that modeled air quality in downtown Fairbanks is sensitive to abundances of background pollutants that can be transported into the city. This is due to the dominant atmospheric chemical reactions that occur in the extreme cold and dark conditions of Arctic winter which is sensitive to background ozone. These findings have implications for air quality attainment modeling. Key Points: Regional transport has a large impact on Fairbanks NOx due to dominant role of ozone titration in loss of NOPM2.5 is affected by regional transport of existing particulate matter, but not precursorsChemical boundary conditions produce significant model‐model differences, with implications for air quality attainment modeling [ABSTRACT FROM AUTHOR]
ISSN:2169897X
DOI:10.1029/2025JD045353