Articles | Volume 12, issue 24
Atmos. Chem. Phys., 12, 11833–11856, 2012
Atmos. Chem. Phys., 12, 11833–11856, 2012

Research article 17 Dec 2012

Research article | 17 Dec 2012

Development of the RAQM2 aerosol chemical transport model and predictions of the 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 M. Kajino et al.
  • 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, the Regional Air Quality Model 2 (RAQM2), was developed to simulate the Asian air quality. We implemented a simple version of a triple-moment modal 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 four categories: particles in the Aitken mode (ATK), soot-free particles in the accumulation mode (ACM), soot aggregates (AGR), and particles in the coarse mode (COR). The aerosol size distribution in each category is characterized by a single mode. The condensation, evaporation, and Brownian coagulations for each mode were solved dynamically. A regional-scale simulation (Δx = 60 km) was performed for the entire year of 2006 covering the Northeast Asian region. The modeled PM1/bulk ratios of the chemical components were consistent with observations, indicating that the simulated aerosol mixing types were consistent with those in nature. The non–sea-salt SO42− mixed with ATK + ACM was the largest at Hedo in summer, whereas the SOSO42− was substantially mixed with AGR in the 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, which is located upwind toward the Asian continent. The condensation of HNO3 onto sea salt particles during transport over the ocean accounts for the difference in the NO3 mixing type at the two sites. Because the aerosol mixing type alters the optical properties and cloud condensation nuclei activity, its accurate prediction and evaluation are indispensable for aerosol-cloud-radiation interaction studies.

Final-revised paper