Comparative study of 3D numerical and puff models for dense air pollutants

To prepare for a chemical emergency response program in those industrial ci ties that might involve a release of chemical contaminants to the atmospher e, we have adopted a series of source emission models and a three-dimension al atmospheric model along with its companion diffusion module for predicti ng the dispersion and concentrations of these hazardous chemicals with vari ous types of release scenarios. The three-dimensional atmospheric model pre dicts the wind, temperature, and turbulence fields in which the physical pr ocesses associated with terrain, clouds, radiation, and surface vegetation are included. The analytical framework is designed by the fact that the dif fusion module uses the estimated release rate from a source emission model and the predicted winds and turbulence conditions from the atmospheric mode l to compute particle trajectories, concentrations, and dosages in the area of a release. In addition, the model results have been coupled with the ge ographical information system, which may be used for risk assessment at the urban industrial area of south Taiwan by emergency planners.