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Appropriate policies to improve air quality by reducing anthropogenic emissions are urgently needed. This is typified by the particulate matter (PM) problem and it is well known that one type of PM, sulfate aerosol (SO 4 2- ), has a large-scale impact due to long range transport. In this study we evaluate the source-receptor relationships of SO 4 2- over East Asia for 2005, when anthropogenic sulfur dioxide (SO 2 ) emissions from China peaked. SO 2 emissions from China have been declining since 2005-2006, so the possible maximum impact of Chinese contributions of SO 4 2- is evaluated. This kind of information provides a foundation for policy making and the estimation of control effects. The tagged tracer method was applied to estimate the source apportionment of SO 4 2- for 31 Chinese province-scale regions. In addition, overall one-year source apportionments were evaluated to clarify the seasonal dependency. Model performance was confirmed by comparing with ground-based observations over mainland China, Taiwan, Korea, and Japan, and the model results fully satisfied the performance goal for PM. We found the following results. Shandong and Hebei provinces, which were the largest and second largest SO 2 sources in China, had the greatest impact over the whole of East Asia with apportionments of around 10-30% locally and around 5-15% in downwind receptor regions during the year. Despite large SO 2 emissions, the impact of south China (e.g., Guizhou, Guangdong, and Sichuan provinces) was limited to local impact. These results suggest that the reduction policy in south China contributes to improving the local air quality, whereas policies in north and central China are beneficial for both the whole of China and downwind regions. Over Taiwan, Korea, and Japan, the impact of China was dominant; however, local contributions were important during summer., (Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.)

In the framework of the model intercomparison study—Asia Phase II (MICS2), where eight models are compared over East Asia, this paper studies the influence of different parameterizations used in the aerosol module on the aerosol concentrations of sulfate and nitrate in . An intracomparison of aerosol concentrations is done for March 2001 using different configurations of the aerosol module of one of the model used for the intercomparison. Single modifications of a reference setup for model configurations are performed and compared to a reference case. These modifications concern the size distribution, i.e. the number of sections, and physical processes, i.e. coagulation, condensation/evaporation, cloud chemistry, heterogeneous reactions and sea-salt emissions. Comparing monthly averaged concentrations at different stations, the importance of each parameterization is first assessed. It is found that sulfate concentrations are little sensitive to sea-salt emissions and to whether condensation is computed dynamically or by assuming thermodynamic equilibrium. Nitrate concentrations are little sensitive to cloud chemistry. However, a very high sensitivity to heterogeneous reactions is observed. Thereafter, the variability of the aerosol concentrations to the use of different chemistry transport models (CTMs) and the variability to the use of different parameterizations in the aerosol module are compared. For sulfate, the variability to the use of different parameterizations in the aerosol module is lower than the variability to the use of different CTMs. However, for nitrate, for monthly averaged concentrations averaged over four stations, these two variabilities have the same order of magnitude. [Copyright &y& Elsevier]

This paper presents a modal aerosol model (MAM) developed to be used in three dimensional air quality models. MAM, which represents the aerosol distribution with four modes, has the advantage of simplicity and speed efficiency associated to modal models, while mass transfer is modeled with a dynamic approach. To assess the ability of MAM to represent mass transfer, MAM is compared to a size-resolved model based on the dynamic approach and to a version of MAM based on an equilibrium approach. Comparisons are done using measurements of inorganic species made in Japan as initial conditions. Furthermore, it is shown that MAM combined with a well chosen mode splitting scheme is able to deal accurately with the simultaneous occurrence of strong nucleation/condensation and coagulation, as may be observed in high nucleation episodes. [ABSTRACT FROM AUTHOR]