Numerical Study on Concentration Distributions of Sulfur Compounds and Their Budgets over East Asia in the Springtime

A coupled regional chemical transport modeling system is applied to investigate the time spatial variations in sulfur dioxide and sulfate aerosol concentration over East Asia,especially to illustrate transport and chemical conversion of sulfur dioxide on 9~12 April,when the Happo,Oki and Hedo sites in Japan and part of the Japan Sea experienced a high sulfur dioxide episode revealed in the observations.Analysis of model results shows that the emissions from the Miyakejima volcano located to the south of Tokyo,Japan,had a strong impact on sulfur dioxide and sulfate aerosol concentration distributions over Japan islands and the surrounding areas,and were the dominant contributor to the high sulfur dioxide episode over the observation sites and the Japan Sea.Sulfur budgets for March 1 to April 30 indicate that the gasphase and the aqueous phase had the same importance in oxidizing sulfur oxide,and about 42% sulfur compounds(≈25% in sulfur dioxide) emitted in the model domain was transported out,while about 57%(≈35% by wet removal processes) deposited in the domain.