Verification of Chemical Transport Models for PM2.5 Chemical Composition Using Simultaneous Measurement Data over Japan

Abstract

Evaluation of models for simulating temporal and spatial variations of PM 2.5 chemical composition in Japan has been limited by the lack of observational data. In this study, we used PM 2.5 chemical composition data measured simultaneously over several regions of Japan in winter, spring, and summer 2012 to evaluate three sensitivity simulations, one based on a secondary organic aerosol (SOA) yield model and two based on a volatility basis set (VBS) model. Concentrations of sulfate (SO 4 2-), nitrate (NO 3 -), and ammonium (NH 4 + ) were well reproduced by all the simulations in summer. However, in winter and spring, SO 4 2-concentrations were underestimated and NO 3 -concentrations were overestimated by the standard simulation. NO 3 -concentrations were better reproduced by a model with dry-deposition velocities of nitric acid and ammonia enhanced by a factor of 5, as was done in a previous study. Observed concentrations of elemental carbon and organic aerosol (OA) were higher at urban sites than at the surrounding remote sites, and this behavior was not adequately reproduced by models with a grid size of 15 km. Further refinements of emission inventories and models are necessary for better simulations of PM 2.5 chemical compositions. OA concentration was greatly underestimated by the simulation based on the SOA yield model over all the seasons but was better reproduced by the simulations based on the VBS model in spring and summer because aging reactions were considered in the VBS model-based simulations. The VBS model-based simulations reproduced the observations that primary OA predominated in winter and that the contribution of SOA was higher than that of primary OA in spring and summer. These contributions should be validated by means of observation-based source contributions of OA in future studies.

Observed and Modeled Mass Concentrations of Organic Aerosols and PM2.5 at Three Remote Sites around the East China Sea: Roles of Chemical Aging

“…Threedimensional model simulations implementing this scheme show increased mass concentrations of organics, yielding better agreement with observations over the United States, Europe, and at a global scale (e.g., Fountoukis et al, 2011;Jathar et al, 2011;Ahmadov et al, 2012;Barbet et al, 2016). Recently, the VBS scheme has been introduced into regional model simulations for East Asia (Matsui et al, 2014;Morino et al, 2014Morino et al, , 2015Han et al, 2016;Lin et al, 2016). As some of these studies focused on urban conditions, only a subset has analyzed the regional-scale features in the context of continental outflows from East Asia.…”

“…Tai (36.27°N, 117.10°E; 1545 m above sea level (asl)), Shandong Province, China. Morino et al (2015) used filter analysis data from six remote/rural sites in Japan (Tsushima, Oki, Kyotango, Tateyama, Sado, and Rishiri). Clearly more observational data from the East China Sea region are desired to obtain a better context, particularly for occasions of transport of continental air masses with high aerosol loadings.…”

Overview of Model Inter-Comparison in Japan’s Study for Reference Air Quality Modeling (J-STREAM)

“…In particular, issues related to semi-volatile and condensable organic compounds have been extensively studied in Japan [15] and worldwide, e.g., [16]. On the other hand, issues related to vertical diffusion and secondary inorganic aerosols remain unsolved.…”

“…On the other hand, issues related to vertical diffusion and secondary inorganic aerosols remain unsolved. Although the implications of dry deposition velocities of NH 3 and HNO 3 were adapted to the air quality study in Japan [15,17], specific measurements are urgently required to increase our understanding of the behavior of fine particulate nitrate. In addition, photochemical ozone was not targeted, and comparisons with models other than CMAQ was scarce in UMICS.…”

Lower than expected volatility of secondary organic aerosols formed during α-pinene ozonolysis

“…Volatility basis-set (VBS) models have improved the prediction of atmospheric SOA levels by accounting for the decrease in SOA volatility with photochemical aging . Our group recently compared 25 the results of VBS model simulations with observational data from several urban and rural sites leeward of mainland East Asia (Morino et al, 2015). The VBS model improved the prediction of ambient organic aerosol levels in spring and summer, but still included large uncertainties.…”