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ANTHROPOGENIC ENHANCEMENTS TO PRODUCTION OF HIGHLY OXYGENATED MOLECULES FROM AUTOXIDATION (AGU 2018)
Citation:
Pye, H., R. Mathur, J. Xing, E. D’Ambro, B. Lee, S. Schobesberger, M. Takeuchi, Y. Zhao, F. Lopez-Hilfiker, J. Liu, J. Shilling, A. Middlebrook, J. Liao, A. Welti, M. Graus, C. Warneke, J. de Gouw, J. Holloway, T. Ryerson, I. Pollack, AND J. Thornton. ANTHROPOGENIC ENHANCEMENTS TO PRODUCTION OF HIGHLY OXYGENATED MOLECULES FROM AUTOXIDATION (AGU 2018). AGU Fall Meeting, Washington, DC, December 10 - 14, 2018.
Impact/Purpose:
The NGAQM will incorporate chemistry that is 1.) scale-appropriate, 2.) documented and transparent, 3.) robust and 4.) condensed. Different chemical mechanisms will be developed for different applications but they will all be traceable to a detailed, evaluated archive of atmospheric chemistry information.
Description:
Abstract: Monoterpene oxidation is a significant source of organic aerosol in locations with abundant biogenic emissions. In this work, we show that the lack of autoxidation in models and experimental data used to parameterize them limits our ability to predict correct amounts of monoterpene SOA (MTSOA) in chemical transport models. Furthermore, we show that capturing the role of anthropogenic emissions (NOx vs primary and secondary organic aerosol) in modulating MTSOA depends on representing autoxidation. To demonstrate these features, we develop a molecular-level understanding of prompt (first generation) MTSOA from OH oxidation and evaluate our mechanism against laboratory experiments conducted at timescales of <10s and multiple hours. The mechanism is then applied to the ambient atmosphere to reveal that autoxidation is a substantial fraction of the peroxy radical fate in the current southeastern US, highly oxygenated organic molecules (HOM) are enhanced in the presence of NOx, and changes in autoxidation-NOx-oxidant couplings have resulted in reductions in prompt MTSOA in the southeastern US since the 1990s.
