MODELING OF ORGANIC CARBON AEROSOL DISTRIBUTIONS OVER EAST ASIA IN THE SPRINGTIME

1. Introduction Atmospheric aerosols are a chemical mixture of solid and liquid particles suspended in ambient air. They range in size from the smallest superfine particles, having di-ameters of a few nano-meters (nm), to coarse mode parti-cles, with diameters of several micrometers (mm) or more. From a climatic point of view, probably the most critical subset of atmospheric aerosols are those in the fine or accumulation mode, having diameters ranging from about 0.1 mm to a few micrometers. Th…

MODELING OF ORGANIC CARBON AEROSOL DISTRIBUTIONS OVER EAST ASIA IN THE SPRINGTIME

The Models-3 Community Multi-scale Air Quality (CMAQ) modeling system coupled with the Regional Atmospheric Modeling System (RAMS) is applied to East Asia to investigate the transport and evolution processes of organic carbon (OC) aerosols in the springtime of 2001. The simulated OC mixing ratios are compared with ground level observations at three remote sites in Japan during the Aerosol Characterization Experiment Asia (ACE-Asia) field campaign. It is found that the modeled OC concentrations are generally in good agreement with the observed ones, and the model reproduces the time variations in OC mixing ratios reasonably well. Model results show that high levels (larger than 16 mg.m-2) of column burden of OC aerosols concentrated in the middle reaches of Yangtse River and southern China, and that in most regions of China to the south of Yellow River the column burden was over 7 mg.m-2, while the isopleth of 4 mg.m-2 extended to the inner area of northwestern Pacific Ocean.