Abstract. In this study bulk airborne aerosol composition measured by the PILS-IC (integration time of 3 min 24 s) during TRACE-P P3B Flight 10 are used to investigate the ionic chemical composition and mixing state of biomass burning particles. A biomass burning plume, roughly 3-4 days old, moderately influenced by urban pollution aerosols recorded in the Philippine Sea is investigated. Focusing on the fine particle NO , and Organic anions, the measurements suggest that aerosols could be composed of biomass burning particles (KNO 3 ) mixed to a large degree externally with the (NH 4 ) 2 SO 4 aerosols. A "closed-mode" thermodynamic aerosol simulation predicts that a degree of external mixing (by SO 2− 4 mass) of 60 to 100% is necessary to achieve the observed ionic associations in terms of the existence of KNO 3 . However, the degree of external mixing is most likely larger than 90%, based on both the presence of KNO 3 and the amounts of NH 4 NO 3 . Calculations are also shown that the aerosol mixing state significantly impacts particle growth by water condensation/evaporation. In the case of P3B Flight #10, the internal mixture is generally more hygroscopic than the external mixture. This method for estimating particle mixing state from bulk aerosol data is less definitive than single particle analysis, but because the data are quantitative, it may provide a complementary method to single particle chemical analysis.

The meteorologically adjusted long term variations of the surface ozone concentrations over 6 major cities in Korea were determined by using the low-pass Kolmogorov and Zurbenko (KZ)-filter and multiple linear regressions. In addition, by using the OZone Isopleth Plotting package for Research-oriented version (OZIPR), the variation of ozone induced by the change of precursor emissions was separated from the long term variation of ozone over Seoul, thus the relative contribution of the background ozone concentration was deduced. Although both the effects of precursor emission and background level change have increased the surface ozone concentration from 2001 to 2008, it is inferred that the background effect is about 2.5 times higher than the precursor emissions change on the surface ozone concentration over Seoul. The relative importance of the background effect might be increasing as the emissions in Northeast Asia increase, while the effect of precursor emission could be reduced by continuous implementation of emission control strategies in Seoul.

A multicomponent aerosol dynamic model, that is suitable for regional/global chemical transport models, was developed by combining a thermodynamic module and a modal approach module and by using a dynamic gas/aerosol relationship. The modal approach, which represents the particle size distribution as the superposition of three log-normal size distributions without any assumption on the characteristics of the log-normal distribution, was introduced for simulating the evolution of the chemical species of aerosol particles efficiently. The dynamic approach was utilized for gas/particle transport mechanisms to simulate mass transfer between the gas phase and size-resolved aerosol particles. Both dynamic approachesthe local equilibrium method and global equilibrium method-are compared, and the importance of dynamic approach compared to the equilibrium approach is demonstrated. It is also shown that the global equilibrium method can reduce the computing time significantly compared to the conventional local equilibrium method without much loss of accuracy.

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