A numerical investigation of urban influences on local meteorological conditions during the Bhopal gas accident

A three-dimensional mesoscale model (Mahrer and Pielke, 1977) was used to investigate possible urban effects on the prevailing meteorological conditions during the Bhopal gas leak. A distinct urban heat island circulation was formed when a gradient of 6°C exists between the city area of Bhopal and the rural area and when the geostrophic wind at 850 mb level is very weak (i.e., 1 m s-1). However, when the wind speed at 850 mb level was increased to the observed speed of 3 m s-1, the urban heat island circulation disappeared. The modelling experiments indicate that under the prevailing synoptic conditions, the urban circulation should not have had a major influence on the local meteorological conditions during the Bhopal gas accident.