Comparison of Urban Atmospheric Dispersion Simulations Considering Building and Terrain Conditions: Lagrangian Particle Dispersion Model and Gaussian Plume Model

Accurate modeling of radioactive dispersion in urban environments is essential for public safety. This study evaluates the predictive characteristics and practical applicability of two atmospheric dispersion models: the Lagrangian particle model (PALM-LPM) and the Gaussian plume model (AERMOD), under stable boundary layer conditions in central Seoul, Korea. Simulations were performed within a 2-km radius of Gwanghwamun Square to assess the model characteristics and dispersion patterns. PALM-LPM demonstrated strong predictive accuracy by effectively resolving urban turbulence and geometry, though at a high computational cost. In contrast, AERMOD delivered faster results but struggled to accurately represent complex structures. These results reveal significant differences in dispersion and deposition depending on the presence of buildings and terrain. Urban structures influence the dispersion pathways and contribute to areas of concentration stagnation. The findings suggest that the choice of dispersion model should depend on specific goals and conditions of the application, balancing both accuracy and computational efficiency. This study provides a scientific basis for selecting models in cases of regulatory dose assessment and urban radiological emergency response planning.