Preprints
https://doi.org/10.5194/egusphere-2023-3082
https://doi.org/10.5194/egusphere-2023-3082
03 Jan 2024
 | 03 Jan 2024

Shallow boundary layer heights controlled by the surface-based temperature inversion strength are responsible for trapping home heating emissions near the ground level in Fairbanks, Alaska

Meeta Cesler-Maloney, William Simpson, Jonas Kuhn, Jochen Stutz, Jennie Thomas, Tjarda Roberts, Deanna Huff, and Sol Cooperdock

Abstract. In cold climate cities, like Fairbanks, Alaska, during winter, reduced vertical mixing in the atmosphere leads to pollution trapping and concerningly high PM2.5 concentrations at ground level. To study pollution trapping, we simulated dispersion of SO2 from home heating emissions during the ALPACA-2022 field study in Fairbanks, Alaska using the Platform for Atmospheric Chemistry and Transport one-dimensional model (PACT-1D). Eddy diffusion coefficients that control vertical transport were parameterized by the near-surface temperature inversion strength according to stable boundary layer (SBL) theory and horizontal export was calculated from the wind speed. The model parameterized the SBL height as a function of the near-surface inversion strength, with the SBL height varying between 50 m for weak inversions down to 20 m for strong inversions. The model results were compared to long-path differential optical absorption spectroscopy (LP-DOAS) concentration profiles and in-situ observations of SO2 over the range of 3 m to 191 m above downtown Fairbanks over a 33-day period in winter and achieved excellent agreement (R = 0.88). Sensitivity studies showed that the model is most sensitive to the SBL height and the associated eddy diffusivity profile. Model-derived pollution residence times in Fairbanks are on the order of hours during winter, with a median steady state residence time of 2.1 hours under stable atmospheric conditions, indicating there is limited time for chemical processing.

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Meeta Cesler-Maloney, William Simpson, Jonas Kuhn, Jochen Stutz, Jennie Thomas, Tjarda Roberts, Deanna Huff, and Sol Cooperdock

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-3082', Anonymous Referee #1, 31 Jan 2024
    • AC3: 'Reply on RC1 -- See unified reply', William R. Simpson, 22 Mar 2024
  • RC2: 'Comment on egusphere-2023-3082', Anonymous Referee #2, 07 Feb 2024
    • AC4: 'Reply on RC2 -- See unified reply', William R. Simpson, 22 Mar 2024
  • EC1: 'Comment on egusphere-2023-3082', Michael Tjernström, 18 Mar 2024
    • AC1: 'Reply on EC1', William R. Simpson, 18 Mar 2024
    • AC2: 'Reply to Editor and both reviews', William R. Simpson, 22 Mar 2024
Meeta Cesler-Maloney, William Simpson, Jonas Kuhn, Jochen Stutz, Jennie Thomas, Tjarda Roberts, Deanna Huff, and Sol Cooperdock

Data sets

Gas and meteorological measurements at the CTC site and Birch Hill in Fairbanks, Alaska, during the ALPACA-2022 field study William Simpson, Meeta Cesler-Maloney, and Ryan Hoskins-Chaddon https://doi.org/10.18739/A27D2Q87W

Meeta Cesler-Maloney, William Simpson, Jonas Kuhn, Jochen Stutz, Jennie Thomas, Tjarda Roberts, Deanna Huff, and Sol Cooperdock

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Latest update: 20 Jun 2024
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Short summary
We used a one-dimensional model to simulate how pollution in Fairbanks, Alaska, accumulates in shallow layers near the ground when temperature inversions are present. We find pollution accumulates in a 20 m to 50 m thick layer. The model agrees with observations of SO2 pollution using only home heating emissions sources, which shows that ground-based sources dominate sulfur pollution in downtown Fairbanks. Air residence times in downtown are only a few hours, limiting chemical transformations.