Development of the RAQM2 aerosol chemical transport model and predictions of the Northeast Asian aerosol mass, size, chemistry, and mixing type

摘要

pstrongAbstract./strong 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-??m. 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 (Δix/i = 60 km) was performed for the entire year of 2006 covering the Northeast Asian region. The modeled PMsub1/sub/bulk ratios of the chemical components were consistent with observations, indicating that the simulated aerosol mixing types were consistent with those in nature. The nona??sea-salt SOsub4/subsup2−/sup mixed with ATK + ACM was the largest at Hedo in summer, whereas the SOSOsub4/subsup2−/sup was substantially mixed with AGR in the cold seasons. Ninety-eight percent of the modeled NOsub3/subsup−/sup was mixed with sea salt at Hedo, whereas 53.7% of the NOsub3/subsup−/sup was mixed with sea salt at Gosan, which is located upwind toward the Asian continent. The condensation of HNOsub3/sub onto sea salt particles during transport over the ocean accounts for the difference in the NOsub3/subsup−/sup 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./p.