Abstract
An analytical dispersion model for point, line and area sources is formulated in this work. The analytical solution of an advection-diffusion equation with the Neumann (total reflection) boundary conditions for a bounded domain is obtained for point sources using the separation of variable and wind speed as a power law profile of vertical height above the ground. The downwind and vertical eddy diffusivities are considered as an explicit function of downwind distance and vertical height. The formulations for line and area sources are obtained by integrating the point source formulation in crosswind, crosswind and downwind directions, respectively. A gridded emissions inventory of Delhi City for the year 2008–09 has been developed to estimate the strength of emissions from various sources, namely vehicles, industries, power plants and domestic sources, and this has been made using primary and secondary data of PM10 (particulate matter with aerodynamic diameter ≤ 10 µm). Dispersion models generally require steady and horizontally homogeneous hourly surface and upper air meteorological observations. However, hourly meteorological observations are not easily available for most of the locations in India. To overcome this limitation, meteorological variables are computed using the Weather Research and Forecast (WRF) model (version 3.1.1) developed by the National Center for Atmospheric Research (NCAR). The performance of this analytical model is evaluated through concentrations of PM10 monitored at different locations in Delhi. The observed data for the period December 2008 has been obtained from the Central Pollution Control Board (CPCB). The model’s predicted values are found to be in good in agreement with the observed values. However, the model results depend on the accuracy of source strength data, i.e., the estimated values of emission rates for the various air pollutants.
Highlights
The atmospheric diffusion equation (Seinfeld, 1986) has long been used to describe the dispersion of airborne pollutants in a turbulent atmosphere
The downwind and vertical eddy diffusivities are considered as an explicit function of vertical height and downwind distance from the source, which is applicable to simulate the concentration in low wind condition
The analytical models for dispersion of air pollutants released from point, line and area sources are formulated by considering the wind speed as a power law profile of vertical height above the ground and horizontal and vertical eddy diffusivity as an explicit function of downwind distance from the source and vertical height in different boundary conditions, which is applicable to simulate the concentration in low wind
Summary
The atmospheric diffusion equation (Seinfeld, 1986) has long been used to describe the dispersion of airborne pollutants in a turbulent atmosphere. The use of analytical solutions of this equation was the first and remains the convenient way for modelling the air pollution study (Demuth, 1978). Air dispersion models based on its analytical solutions posses several advantages over numerical models, because all the influencing parameters are explicitly expressed in a mathematically closed form. Most of the estimates of dispersion are based on the Gaussian plume model, which assumes the constant wind speed and turbulent eddies with height. Hinrichsen (1986) compared a non-Gaussian model, in which wind speed and turbulence, are not constant with height and non Gaussian model agreed better with the Most of the estimates of dispersion are based on the Gaussian plume model, which assumes the constant wind speed and turbulent eddies with height. Hinrichsen (1986) compared a non-Gaussian model, in which wind speed and turbulence, are not constant with height and non Gaussian model agreed better with the
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
