Atmos. Chem. Phys. Discuss., 12, 13405-13456, 2012
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Development of an aerosol chemical transport model RAQM2 and predictions of Northeast Asian aerosol mass, size, chemistry, and mixing type
M. Kajino1,2, Y. Inomata3, K. Sato3, H. Ueda4, Z. Han5, J. An5, G. Katata6, M. Deushi1, T. Maki1, N. Oshima1, J. Kurokawa3, T. Ohara7, A. Takami7, and S. Hatakeyama8
1Meteorological Research Institute, Japan Meteorological Agency, 1–1 Nagamine, Tsukuba 305-0052, Japan
2Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352, USA
3Asia Center for Air Pollution Research, 1182 Sowa, Nishi, Niigata 950-2144, Japan
4Toyohashi Institute of Technology, 1-1 Hibarigaoka, Tempaku, Toyohashi 950-2144, Japan
5Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
6Japan Atomic Energy Agency, 2-4 Shirakata-shirane, Tokai, Ibaraki 319-1195, Japan
7National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506, Japan
8Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan

Abstract. A new aerosol chemical transport model, Regional Air Quality Model 2 (RAQM2), was developed to simulate Asian air quality. We implemented a simple version of a modal-moment aerosol dynamics model (MADMS) and achieved a completely dynamic (non-equilibrium) solution of a gas-to-particle mass transfer over a wide range of aerosol diameters from 1 nm to super μm. To consider a variety of atmospheric aerosol properties, a category approach was utilized, in which the aerosols were distributed into 4 categories: Aitken mode (ATK), soot-free accumulation mode (ACM), soot aggregates (AGR), and coarse mode (COR). Condensation, evaporation, and Brownian coagulations for each category were solved dynamically. A regional-scale simulation (Δ x = 60 km) was performed for the entire year of 2006 covering the Northeast Asian region. Statistical analyses showed that the model reproduced the regional-scale transport and transformation of the major inorganic anthropogenic and natural air constituents within factors of 2 to 5. The modeled PM1/bulk ratios of the chemical components were consistent with the observations, indicating that the simulations of aerosol mixing types were successful. Non-sea salt SO42- mixed with ATK + ACM was the largest at Hedo in summer, whereas it mixed with AGR was substantial in cold seasons. Ninety-eight percent of the modeled NO3- was mixed with sea salt at Hedo, whereas 53.7% of the NO3- was mixed with sea salt at Gosan, located upwind toward the Asian continent. The condensation of HNO3 onto sea salt particles during transport over the ocean makes the difference in the NO3- mixing type at the two sites. Because the aerosol mixing type alters optical properties and cloud condensation nuclei activity, its accurate prediction and evaluation are indispensable for aerosol-cloud-radiation interaction studies.

Citation: Kajino, M., Inomata, Y., Sato, K., Ueda, H., Han, Z., An, J., Katata, G., Deushi, M., Maki, T., Oshima, N., Kurokawa, J., Ohara, T., Takami, A., and Hatakeyama, S.: Development of an aerosol chemical transport model RAQM2 and predictions of Northeast Asian aerosol mass, size, chemistry, and mixing type, Atmos. Chem. Phys. Discuss., 12, 13405-13456, doi:10.5194/acpd-12-13405-2012, 2012.
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