Evaluating Oxidant Field Representations in Aerosol Modeling: Insights from the ASIA-AQ Campaign and Global Budgets
Year: 2026
Type: preprint
Abstract: . Accurate prediction of secondary inorganic aerosols (e.g., sulfate and nitrate) relies heavily on representing highly variable, nonlinear atmospheric oxidant chemistry. This study systematically evaluates the sensitivity of GOCART-2G aerosol simulations to the temporal resolution and underlying chemical mechanisms of three oxidant fields: hourly GEOS-Chem (CFH), monthly GEOS-Chem (CFM), and monthly GMI-Chem climatology (GMI). Model performance was assessed using airborne data from the 2024 ASIA-AQ campaign (covering the Philippines, South Korea, and Thailand) and global simulations for 2019. Comparisons show that hourly, time-varying oxidant fields improve simulated oxidant, sulfate, and nitrate correlations over monthly averages. Capturing short-term variability—particularly the strong diurnal cycles of OH and NO3—preserves the temporal covariance and nonlinear coupling that monthly means obscure. Consequently, time-resolved oxidants weaken the overall chemical transformation of dimethyl sulfide (DMS). This results in ~20 % higher global DMS and methanesulfonic acid (MSA) burdens than monthly mean simulations, while exerting substantial regional impacts (>20 %) on sulfur and nitrate budgets over East Asia. Furthermore, variations in monthly mean oxidant magnitude and spatial distribution between GMI-Chem and GEOS-Chem mechanisms impact aerosol burdens. GMI-Chem produces 2 % and 8 % higher column and surface sulfate, respectively, but 148 % and 130 % lower column and surface nitrate. These findings highlight the limitations of decoupled, time-averaged oxidant fields in traditional global models, demonstrating that resolving high-frequency temporal variability and nonlinear feedbacks is critical for Earth System Models.
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225820982
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