Atmospheric diffusion model of secondary pollutants with settling

Abstract

time-dependent mathematical model of chemically reactive atmospheric primary pollutants and their byproduct in a protected zone above the surface layer has been developed to study the impact of removal of larger particles when the heavy admixture is present. The different meteorological and source parameters in the surface layer (SL), including a settling velocity term, have been taken into account through appropriate boundary conditions. The variation of surface layer and mixing layer heights on atmospheric stability, geostrophic drag by terrain and several other meteorological parameters are also treated. The results have been analysed for stable and neutral atmospheric conditions. It is shown that the effect of settling velocity on concentration of secondary pollutants is significant in a stable layer compared to the neutral case. Further, the effect of chemical reaction of a primary pollutant is to increase the concentration of secondary pollutant throughout the protected zone for all values of chemical reaction rate and the effect of settling is to increase the concentration in the lower part of the protected zone for certain ranges of settling velocity. In the upper part, the effect of settling is to decrease the concentration for all values of settling velocity. It is interesting to note that the effect of chemical reaction rate has virtually no impact on the formation of secondary pollutant at short travel time but has significant effect at large travel time.