7. Analysis of an Aerosol Environment in an Urban Region and Its Impact on Regional Meteorology

The aerosol environment over a region is a potential parameter to perturb the regional meteorology and it remains as a large source of uncertainties. This chapter presents an analysis of the aerosol environment over Kolkata, a densely-populated metropolitan area in the Eastern India, near to the land-ocean boundary of Bay of Bengal. Along with the natural sources of aerosols, anthropogenic aerosols constantly contribute to the total aerosol loading in this region. This analysis shows how the spectral dependence pattern of aerosol optical parameters estimates the dominant type of aerosols over a region. Furthermore, the investigation shows the impact of the dominant type of aerosols on the boundary layer meteorology utilizing ground based observations. In the course of this discussion, the role of atmospheric black carbon (BC) aerosols in controlling the aerosol environment is focused. This urban region experiences much high BC concentrations mostly originating from incomplete combustion of fossil fuel used in vehicles. The chapter also includes a discussion on back trajectory analysis showing the influence of transported air masses on the regional aerosol environment. The investigation presented in this chapter depicts significant perturbation in the boundary layer temperature profile in association with the abundance of pollutant aerosols which in turn can affect the normal atmospheric convective processes over a region. This chapter contributes to a better understanding of impact of pollutant aerosols on the regional meteorology and thermodynamic processes.