Integrating buoyant gas diffusion scheme and chemical conversion scheme in FLEXPART-WRF for chemical gas dispersion and chemical emergency impact assessment

In this work the effects of buoyancy and chemical conversion in atmospheric transport and impact assessment of chemical/toxic gas (e.g. NH₃, Cl, LPG etc.) releases during chemical industrial emergencies are studied by incorporating buoyant gas diffusion and pseudo first-order chemical conversion scheme in the Lagrangian particle dispersion model FLEXPART-WRF. The results indicate that • Daytime simulated ground level concentration (GLC) of NH₃ decreases significantly due to strong buoyancy effects within convective BL. • Nighttime GLC of NH₃ reduces significantly due to chemical conversion in shallow stratified BL. • Overall nighttime GLC is higher than daytime due to near-ground stratification of stable BL