A Numerical Simulation of Acid Deposition in East Asia

The goal of the present study is to do a long term simulation and to derive a source receptor-relation using a comprehensive Eulerian acid deposition model coupled with a dynamic meteorological model. The selected modeling period is from March 1 to April 30, 1996. A dynamic meteorological model named MM5 was first used to calculate meteorological fields and then STEM preprocessors were invoked to generate dry deposition velocities and eddy diffusivities. Finally, a multi-scale STEM was applied to simulate both wet and dry acid deposition phenomena. The source-receptor relations were also estimated for sulfate and nitrate species using a counter species method. The model results for SO₂ and O₃ agree very well with measurements. However the model under-predicts the NO₂ concentration due to insufficient grid resolution as well as due to inaccurate field measurement. The transport contribution for total mass and wet deposition is much larger than that of dry deposition.