The manuscript by Murphy et al. reports on the revised treatment of organic aerosol (OA) in the Community Multiscale Air Quality Model (CMAQ) v5.2. The revised treatment of OA includes: 1. partitioning and gas-phase aging of primary OA (POA), and 2. a new model species “pc” (pcVOA, pcSOG, pcSOA) that represents the missing emissions and processes that may be associated with secondary OA (SOA) f...

Abstract: The effect of SO2 in the photooxidation of a mixture of anthropogenic precursors is studied. For that purpose, five experiments with a mixture of 1,3,5-trimethylbenzene, o-xylene, toluene and octane in the presence of HONO were carried out in the EUPHORE outdoor chamber by adding different initial SO2 concentrations in each experiment. The experimental secondary organic aerosol obtain...