Photochemical Modeling of Wintertime HO x Sources and Sinks in a Subarctic Urban Location
Abstract The hydroxyl radical (OH) is a key atmospheric oxidant that is important for regulating pollutant concentrations and particle formation and composition. The globally dominant formation mechanism of OH is ozone photolysis. However, the low-light conditions in the wintertime Arctic may limit OH formation through this pathway, and there is a lack of observations available to explain oxidant chemistry in polar locations. We use the Dynamically Simple Model of Atmospheric Chemical Complexity (DSMACC) 0D model to assess processes controlling the abundances of atmospheric oxidants in a subarctic city. To constrain the model, we use measurements made during the Alaskan Layered Pollution and Chemical Analysis (ALPACA) field campaign, which took place in Fairbanks, Alaska, USA, during the winter of 2022. HONO photolysis to form OH is the major chemical source of HOx in the polluted, low-light environment of wintertime Fairbanks, and formaldehyde is an important precursor for HO2. We find that the HOx budget is distinct between a polluted, strongly stable inversion event and a clean, weakly stable period because of the different meteorology and pollution levels regulating peroxynitric acid (PNA, HO2NO2) cycling. Our results improve our understanding of the unique atmospheric pollution chemistry under cold and low-light conditions.
Authors
- William R. Simpson (ORCID: https://orcid.org/0000-0002-8596-7290)
- S. R. Arnold (ORCID: https://orcid.org/0000-0002-4881-5685)
- Jonas Kuhn (ORCID: https://orcid.org/0000-0002-6953-3281)
- Dwayne E. Heard (ORCID: https://orcid.org/0000-0002-0357-6238)
- Daniel Stone (ORCID: https://orcid.org/0000-0001-5610-0463)
- Alicia Hoffman (ORCID: https://orcid.org/0009-0001-6945-0478)
- Slimane Bekki (ORCID: https://orcid.org/0000-0002-5538-0800)
- Barbara D’Anna (ORCID: https://orcid.org/0000-0001-8915-4097)
- J. Stutz (ORCID: https://orcid.org/0000-0001-6368-7629)
- Kathy S. Law (ORCID: https://orcid.org/0000-0003-4479-903X)
- Meeta Cesler‐Maloney (ORCID: https://orcid.org/0000-0002-2905-549X)
- Fangzhou Guo (ORCID: https://orcid.org/0000-0003-3854-038X)
- James Flynn
- James M. St Clair
- Sol Cooperdock
- Lisa Whalley
- Samuel Seldon
- Rachel L. James
- Brice Temime-Roussel
- Amna Ijaz
Institutions
- Centre National de la Recherche Scientifique (FR)
- University of Leeds (GB)
- Woodwell Climate Research Center (US)
- University of Alaska Fairbanks (US)
- Université de Versailles Saint-Quentin-en-Yvelines (FR)
- Aix-Marseille Université (FR)
- NOAA Oceanic and Atmospheric Research (US)
- Sorbonne Université (FR)
- University of Houston (US)
- Université Paris 1 Panthéon-Sorbonne (FR)
- University of Maryland, Baltimore County (US)
Publication Details
- Journal
- ACS ES&T Air
- Published
- 2026-09-12
- DOI
- https://doi.org/10.1021/acsestair.6c00254
- Primary Topic
- Atmospheric chemistry and aerosols
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Agence Nationale de la Recherche
- Institut Polaire Français Paul Emile Victor
- Directorate for Geosciences
- Institut national des sciences de l'Univers
- Division of Atmospheric and Geospace Sciences
- Integrative and Collaborative Education and Research