Simulation of sulfur transport and transformation in East Asia with a comprehensive chemical transport model

The Models-3 Community Multi-scale Air Quality modeling system (CMAQ) coupled with the Regional Atmospheric Modeling System (RAMS) is applied to East Asia to analyze the production and transport processes of sulfur compounds in the springtime of 2001, when two large field campaigns TRACE-P (TRAnsport and Chemical Evolution over the Pacific) and ACE-Asia (Aerosol Characterization Experiment – Asia) were being conducted over a broad area covering northeastern Asia and the western pacific. Simulated concentrations of sulfur dioxide (SO2) and sulfate aerosol (SO42−) were compared with observed data obtained on the ground level at three remote sites in South Korea and China and onboard aircraft C130, and it was found that the modeling system reproduced many of the important features in the observations, including horizontal and vertical gradients, of the Asian pollution outflow over the western Pacific. Analysis of model results shows that the SO2 and SO42− concentrations exhibited pronounced variations in time and space, with SO2 and SO42− behaving differently due to the interplay of chemical conversion, removal and transport processes.