A two dimensional numerical model of primary pollutant emitted from an urban area source with mesoscale wind, dry deposition and chemical reaction

A two dimensional numerical model has been developed to study the dispersion of a primary pollutant emitted from an urban area source in the presence of mesoscale wind. The model takes into account the transformation and removal mechanisms through chemical reaction, dry deposition and gravitational settling processes. The numerical model is solved using the Crank–Nicolson finite difference scheme under the stability dependent meteorological parameters involved in wind velocities and eddy diffusivity profiles. The urban heat island effect generates its own mesoscale winds and consequently prevents the dispersal of pollutants which will result in an increase in the concentration of pollution in the atmosphere. The analysis shows that the mesoscale wind reduces the concentration of a primary pollutant in the upwind side of centre of heat island and increases the concentration in the downwind side of centre of heat island.