LAUSR

Abstract. Limonene has a strong tendency to undergo ozonolysis to form semi-volatile and low-volatility compounds that contribute to secondary organic aerosols (SOAs) both outdoors and indoors. The influence of NO2 on SOA formation from ozonolysis of limonene has been evaluated using chamber experiments and the Master Chemical Mechanism (MCM) coupled with a gas-particle partitioning model in this work. A series of 21 indoor chamber experiments were carried out with or without NO2 under different [O3]0 / [VOC]0 ratios, and these experimental data were compared with the model simulations. Agreement in SOA yields was observed between the experimental observations and model simulations under varying conditions. Generally, SOA mass yields are positively dependent on [O3]0 / [VOC]0 without the presence of NO2. However, the introduction of NO2 leads to a more complicated change in SOA yield, which is shown to be related to initial [O3] / [VOC] ratios. When [O3]0 / [VOC]0 > 2, the introduction of NO2 results in an increase of SOA yield in the range of NO2 studied in this work; whereas a weak negative effect was found for SOA formation according to the introduction of ~ 250 ppbv NO2 under [O3]0 / [VOC]0