Verification of the local scale atmospheric dispersion model

A three dimensional particle model for local scale atmospheric dispersion was developed to estimate the air concentrations in complex terrain. Lagrangian particle models are effective tool to simulate the atmospheric dispersion of airborne pollutants. In these models, the atmospheric dispersion is evaluated by the motion of fictitious particles consisting of a deterministic part due to the mean wind and a stochastic part related to the turbulent flow. For verification of the particle model, the model is compared with the Gaussian plume and puff models on the same conditions. Gaussian plume model assumes that the turbulence, wind speed and wind direction are steady. The puff model can be considered the local time-varying emissions and meteorological conditions. For the comparison of the particle and the Gaussian plume models, the wind speed and direction are set to the constant on the flat terrain. In the case of the puff model, the space-varying wind components are considered on simple topography. The computed results agreed quite well between the particle and the classical models. The developed particle model for local scale atmospheric dispersion will be used as a sub-module of the real-time radiological dose assessment system named FADAS [1]