simpleGAMMA v1.0 – a reduced model of secondary organic aerosol formation in the aqueous aerosol phase (aaSOA)

摘要

There is increasing evidence that the uptake and aqueous processing ofwater-soluble volatile organic compounds (VOCs) by wet aerosols or clouddroplets is an important source of secondary organic aerosol (SOA). Werecently developed GAMMA (Gas–Aerosol Model for Mechanism Analysis), azero-dimensional kinetic model that couples gas-phase and detailedaqueous-phase atmospheric chemistry for speciated prediction of SOA andorganosulfate formation in cloud water or aqueous aerosols. Results from GAMMAsimulations of SOA formation in aerosol water (aaSOA) (McNeill et al., 2012)indicate that it is dominated by two pathways: isoprene epoxydiol (IEPOX)uptake followed by ring-opening chemistry (under low-NO_x conditions) andglyoxal uptake. This suggested that it is possible to model the majority ofaaSOA mass using a highly simplified reaction scheme. We have thereforedeveloped a reduced version of GAMMA, simpleGAMMA. Close agreement inpredicted aaSOA mass is observed between simpleGAMMA and GAMMA under allconditions tested (between pH 1–4 and RH 40–80 %) after 12 h ofsimulation. simpleGAMMA is computationally efficient and suitable forcoupling with larger-scale atmospheric chemistry models or analyzing ambientmeasurement data.