Global budgets of atmospheric primary and secondary organic aerosols constrained by full-volatility-range organic emissions

Abstract. Organic aerosol (OA) constitutes a major fraction of tropospheric submicron particulate matter, with primary (POA) and secondary (SOA) components exhibiting different physicochemical properties and health impacts. The POA and SOA budgets are however highly uncertain, and the results from different model studies are confusing because of more or less consideration of the volatility distributions of organic precursor emissions and inconsistent attributions of model tracers in model-observation comparisons. Here we develop an OA simulation framework in GEOS-Chem that resolves the full volatility spectrum of organic precursor emissions from anthropogenic sources and open biomass burning. The model reasonably reproduces the observed OC, POA, and SOA concentrations from comprehensive surface, shipborne, and airborne datasets, providing a consistent global validation. The model simulations suggest greater POA (0.5 Tg) and SOA burdens (2.0 Tg) and potentially stronger and more widespread impacts of the OA components on air quality, health, and radiation than previous estimates, led by both of the emission updates and the revised OA scheme. The simulated global SOA production is about 106 Tg in 2018, 46 % of which is contributed by open biomass burning. The results demonstrate distinct regional variations in the dominant source types and population exposure distributions of POA and SOA, highlighting the needs for SOA mitigation, multi-sector control measures, and clean energy replacements for long-term health-oriented air quality improvements globally. The model results are sensitive to the emissions and wet-deposition parameterization, calling for more measurement constraints on local emission factors and the deposition fluxes of OA and its components.