Development of a multiphase chemical mechanism to improve secondary organic aerosol formation in CAABA/MECCA (version 4.5.6-rc.1)

Felix Wieser, Rolf Sander, and Domenico Taraborrelli

Abstract

During the last decades, the impact of multiphase chemistry on secondary organic aerosol (SOA) has been demonstrated to be key in explaining lab experiments and field measurements. However, global atmospheric models still show large biases when simulating atmospheric observations of organic aerosols (OA). Major reasons for the model errors are the use of simplified chemistry schemes of gas-phase oxidation of vapors and parameterization of heterogeneous surface reactions. The photochemical oxidation of anthropogenic and biogenic volatile organic compounds (VOC) leads to products that either produce new SOA or are taken up by existing aqueous media like cloud droplets and deliquescent aerosols. After partitioning, aqueous-phase processing results in polyols, organosulfates, and other products with a high molar mass and oxygen content. In this work, we have introduced the formation of new low-volatility organic compounds (LVOC) into the multiphase chemistry box model CAABA/MECCA. ...