Air Dispersion Modeling Report
AIR DISPERSION MODELING:
A Review of Available Point Source Dispersion Models
Mathematical Modeling of Energy and Environmental Systems
MANE6960H01
Spring 2013
Sarah Mahon
INTRODUCTION
Air dispersion modeling is the mathematical simulation of how pollutants disperse in the atmosphere. Dispersion modeling can be used for multiple purposes; including to model the path of volcanic ash in the atmosphere after an eruption, to model the plume of pollutants emanating from a coal-burning electricity producing plant, to model the impact that an increase in vehicular traffic will have on ambient air conditions, or for establishing evacuation zones after a release of toxic chemicals.
A wide variety of free software is available for public use. To successfully decide which software to use, it is important to understand exactly what needs to be modeled and what output is desired. Models exist for small local scales and larger planetary scales, for dispersion of primary pollutants (such as NOX) or for secondary pollutants (such as ozone, which NOX can convert into), for steady state emissions of particles (from stacks) or for non-steady state puffs (from chemical releases). Model outputs can predict worst case pollutant concentration at a specific point, expected concentrations based on specific atmospheric conditions at a certain point, or create a three-dimensional graphic showing the concentration of a pollutant within space. For example, the Regional Modeling System for Aerosols and Deposition (REMSAD), a program available from the Environmental Protection Agency (EPA) used to model inert and chemically reactive pollutants over regional scales (including processes that contribute to haze), can not be used be emergency response personnel to quickly setup evacuation zones downwind of a hazardous pollutant release.
This report focuses on point source dispersion modeling based on the Gaussian air dispersion equations in order to determine concentrations of
A Review of Available Point Source Dispersion Models
Mathematical Modeling of Energy and Environmental Systems
MANE6960H01
Spring 2013
Sarah Mahon
INTRODUCTION
Air dispersion modeling is the mathematical simulation of how pollutants disperse in the atmosphere. Dispersion modeling can be used for multiple purposes; including to model the path of volcanic ash in the atmosphere after an eruption, to model the plume of pollutants emanating from a coal-burning electricity producing plant, to model the impact that an increase in vehicular traffic will have on ambient air conditions, or for establishing evacuation zones after a release of toxic chemicals.
A wide variety of free software is available for public use. To successfully decide which software to use, it is important to understand exactly what needs to be modeled and what output is desired. Models exist for small local scales and larger planetary scales, for dispersion of primary pollutants (such as NOX) or for secondary pollutants (such as ozone, which NOX can convert into), for steady state emissions of particles (from stacks) or for non-steady state puffs (from chemical releases). Model outputs can predict worst case pollutant concentration at a specific point, expected concentrations based on specific atmospheric conditions at a certain point, or create a three-dimensional graphic showing the concentration of a pollutant within space. For example, the Regional Modeling System for Aerosols and Deposition (REMSAD), a program available from the Environmental Protection Agency (EPA) used to model inert and chemically reactive pollutants over regional scales (including processes that contribute to haze), can not be used be emergency response personnel to quickly setup evacuation zones downwind of a hazardous pollutant release.
This report focuses on point source dispersion modeling based on the Gaussian air dispersion equations in order to determine concentrations of
References: AERMOD Implementation Guide, AERMOD Implementation Workgroup, US Environmental Protection Agency, last revised March 19, 2009. EPA Support Center for Regulatory Atmospheric Modeling, available at http://www.epa.gov/ttn/scram/dispersionindex.htm, accessed April-May, 2013. Fay, James A. and Golomb, Dan S. Energy and the Environment: Scientific and Technological Principles. New York, Oxford University Press, 2012. Turner, Bruce D. Workbook of Atmospheric Dispersion Estimates: Second Edition. Boca Raton, CRC Press LLC, 1994.