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A critical role for autoxidation in the alpha-pinene + OH aerosol system
Pye, H., E. D'Ambro, S. Schobesberger, B. Lee, J. Liu, J. Shiling, AND J. Thornton. A critical role for autoxidation in the alpha-pinene + OH aerosol system. 2017 International Aerosol Modeling Algorithms Conference, Davis, CA, December 06 - 08, 2017.
The National Exposure Research Laboratory (NERL) Computational Exposure Division (CED) develops and evaluates data, decision-support tools, and models to be applied to media-specific or receptor-specific problem areas. CED uses modeling-based approaches to characterize exposures, evaluate fate and transport, and support environmental diagnostics/forensics with input from multiple data sources. It also develops media- and receptor-specific models, process models, and decision support tools for use both within and outside of EPA.
Oxidation of monoterpenes results in efficient formation of secondary organic aerosol (SOA) and is included as an SOA source in most chemical transport models. However, current model parameterizations lack a mechanistic dependence of monoterpene SOA on NOx and oxidant identity (e.g. OH vs. ozone). In this work, we add autoxidation pathways to the Master Chemical Mechanism (MCM) and use constraints from recent literature and chamber experiments to develop a molecular representation of SOA from OH oxidation of alpha-pinene. We evaluate the model’s ability to reproduce SOA yields, molecular structure distribution, and other properties of the observed gas and aerosol systems. We identify missing chemistry in the MCM and highlight the pathways with the most potential to form SOA in the ambient atmosphere.