Simulating the impacts of regional wildfire smoke on ozone using a coupled fire-atmosphere-chemistry model

Publication Date

11-1-2025

Document Type

Article

Publication Title

Atmospheric Environment

Volume

360

DOI

10.1016/j.atmosenv.2025.121404

Abstract

Wildland fires emit pollutants such as fine particulates (PM2.5), and ozone (O3) precursors that can adversely impact air quality. To better understand processes that directly influence smoke transport and plume chemistry, this study leveraged a coupled fire-atmosphere model (WRF-SFIRE-Chem) to quantify the contributions of wildfire smoke to O3 relative to regional anthropogenic emissions. Coupled fire-atmosphere-chemistry simulations were also used to examine how aerosol radiative feedbacks, i.e., smoke shading, modifies smoke transport and plume chemistry. This study investigated a major smoke episode that occurred during the record-breaking 2020 western U.S. wildfire season. Overall, WRF-SFIRE-Chem was able to reproduce the evolution of a regional smoke plume for the August 2020 smoke event. Sensitivity simulations from WRF-SFIRE-Chem show that O3 contributions from wildfire smoke (21 ± 4.4 ppb) were much larger than O3 enhancements from regional anthropogenic emission sources (11 ± 1.3 ppb). Smoke shading also had a large impact on meteorology where incoming solar radiation and 2-m temperature underneath the smoke plume decreased by ∼400 W m−2 and 4 °C, respectively. Smoke shading also altered smoke transport and reduced O3 concentrations within the smoke plume by up to 10 ppb. These results suggest that sizable enhancements in O3 can occur, even in the absence of regional anthropogenic emissions. This research also highlights the importance of accounting for smoke shading within chemical transport models, which proved to be important in the context of both smoke transport and plume photochemistry.

Funding Number

80 NSSC23K1118

Funding Sponsor

University of Utah

Department

Meteorology and Climate Science

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