Bhopal gas leak: A numerical simulation of episodic dispersion

A mesoscale meteorological model coupled with a Lagrangian particle dispersion (LPD) model was used to simulate the Bhopal methyl isocyanate (MIC) gas leak. A simple two layer K-closure version of the Pielke primitive equation meteorological model was used to produce the wind and turbulence fields in the planetary boundary layer (PBL). Initialized by a single 3 m s−1 geostrophic wind, the PBL model produced a low wind speed stable surface layer capped by a 250 m high nocturnal inversion. The results compared well with limited meteorological observations. However, the LPD model failed to produce enough vertical and horizontal mixing to match the extent of the affected area which was derived from the mortality statistics. Recommendations to improve the model physics to accomodate enhanced mixing in urban areas and to treat MIC thermodynamics and chemistry are suggested.