AERMOD
Encyclopedia
The AERMOD atmospheric dispersion modeling
system is an integrated system that includes three modules:
AERMOD also includes PRIME (Plume Rise Model Enhancements) which is an algorithm for modeling the effects of downwash created by the pollution plume flowing over nearby buildings.
(AMS)/United States Environmental Protection Agency
(EPA) Regulatory Model Improvement Committee), a collaborative working group of scientists from the AMS and the EPA. The AERMIC was initially formed in 1991.
The AERMIC developed AERMOD in seven steps:
On April 21 of 2000, the EPA proposed that AERMOD be adopted as the EPA's preferred regulatory model for both simple and complex terrain. On November 9 of 2005, AERMOD was adopted by the EPA and promulgated as their preferred regulatory model, effective as of December 9 of 2005. The entire developmental and adoption process took 14 years (from 1991 to 2005).
www.crcpress.com www.air-dispersion.com
Atmospheric dispersion modeling
Atmospheric dispersion modeling is the mathematical simulation of how air pollutants disperse in the ambient atmosphere. It is performed with computer programs that solve the mathematical equations and algorithms which simulate the pollutant dispersion...
system is an integrated system that includes three modules:
- A steady-state dispersion model designed for short-range (up to 50 kilometers) dispersion of air pollutantAir pollutionAir pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or cause damage to the natural environment or built environment, into the atmosphere....
emissions from stationary industrial sourcesMajor stationary sourceA major stationary source is a source that emits more than a certain amount of a pollutant as defined by the U.S. Environmental Protection Agency...
. - A meteorologicalMeteorologyMeteorology is the interdisciplinary scientific study of the atmosphere. Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw breakthroughs occur after observing networks developed across several countries...
data preprocessorPreprocessorIn computer science, a preprocessor is a program that processes its input data to produce output that is used as input to another program. The output is said to be a preprocessed form of the input data, which is often used by some subsequent programs like compilers...
(AERMET) that accepts surface meteorological data, upper air soundings, and optionally, data from on-site instrument towers. It then calculates atmosphericEarth's atmosphereThe atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
parameters needed by the dispersion model, such as atmospheric turbulenceTurbulenceIn fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...
characteristics, mixing heightsMixed layerThe oceanic or limnological mixed layer is a layer in which active turbulence has homogenized some range of depths. The surface mixed layer is a layer where this turbulence is generated by winds, cooling, or processes such as evaporation or sea ice formation which result in an increase in salinity...
, friction velocity, Monin-Obukov lengthMonin-Obukhov LengthThe is used to describe the effects of buoyancy on turbulent flows, particularly in the lower tenth of the atmospheric boundary layer. It was first defined by Alexander Obukhov in 1946,...
and surface heat flux. - A terrainTerrainTerrain, or land relief, is the vertical and horizontal dimension of land surface. When relief is described underwater, the term bathymetry is used...
preprocessor (AERMAP) whose main purpose is to provide a physical relationship between terrain features and the behavior of air pollution plumes. It generates location and height data for each receptor location. It also provides information that allows the dispersion model to simulate the effects of air flowing over hills or splitting to flow around hills.
AERMOD also includes PRIME (Plume Rise Model Enhancements) which is an algorithm for modeling the effects of downwash created by the pollution plume flowing over nearby buildings.
History of the development of AERMOD
AERMOD was developed by the AERMIC (American Meteorological SocietyAmerican Meteorological Society
The American Meteorological Society promotes the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences and the advancement of their professional applications. Founded in 1919, the American Meteorological Society has a membership...
(AMS)/United States Environmental Protection Agency
United States Environmental Protection Agency
The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
(EPA) Regulatory Model Improvement Committee), a collaborative working group of scientists from the AMS and the EPA. The AERMIC was initially formed in 1991.
The AERMIC developed AERMOD in seven steps:
- Initial model formulation
- Developmental evaluation
- Internal peer reviewPeer reviewPeer review is a process of self-regulation by a profession or a process of evaluation involving qualified individuals within the relevant field. Peer review methods are employed to maintain standards, improve performance and provide credibility...
and beta testingSoftware testingSoftware testing is an investigation conducted to provide stakeholders with information about the quality of the product or service under test. Software testing can also provide an objective, independent view of the software to allow the business to appreciate and understand the risks of software... - Revised model formulation
- Performance evaluation and sensitivity testing
- External peer review
- Submission to the EPA for consideration as a regulatory model.
On April 21 of 2000, the EPA proposed that AERMOD be adopted as the EPA's preferred regulatory model for both simple and complex terrain. On November 9 of 2005, AERMOD was adopted by the EPA and promulgated as their preferred regulatory model, effective as of December 9 of 2005. The entire developmental and adoption process took 14 years (from 1991 to 2005).
Features and capabilities of AERMOD
Some of the primary features and capabilities of AERMOD are:- Source types: Multiple point, area and volume sourcesAir pollution dispersion terminologyAir pollution dispersion terminology includes the words and technical terms that have a special meaning to those who work in the field of air pollution dispersion modeling...
- Source releases: Surface, near surface and elevated sources
- Source locations: Urban or rural locations. Urban effects are scaled by population.
- Plume types: Continuous, buoyant plumesAir pollution dispersion terminologyAir pollution dispersion terminology includes the words and technical terms that have a special meaning to those who work in the field of air pollution dispersion modeling...
- Plume deposition: Dry or wet depositionAir pollution dispersion terminologyAir pollution dispersion terminology includes the words and technical terms that have a special meaning to those who work in the field of air pollution dispersion modeling...
of particulatesParticulatesParticulates – also known as particulate matter , suspended particulate matter , fine particles, and soot – are tiny subdivisions of solid matter suspended in a gas or liquid. In contrast, aerosol refers to particles and/or liquid droplets and the gas together. Sources of particulate matter can be...
and/or gases - Plume dispersionAtmospheric dispersion modelingAtmospheric dispersion modeling is the mathematical simulation of how air pollutants disperse in the ambient atmosphere. It is performed with computer programs that solve the mathematical equations and algorithms which simulate the pollutant dispersion...
treatment: Gaussian modelAir pollution dispersion terminologyAir pollution dispersion terminology includes the words and technical terms that have a special meaning to those who work in the field of air pollution dispersion modeling...
treatment in horizontal and in vertical for stable atmospheres. Non-Gaussian treatment in vertical for unstable atmospheres - Terrain types: Simple or complex terrain
- Building effects: Handled by PRIME downwash algorithms
- Meteorology data height levels: Accepts meteorology data from multiple heights
- Meteorological data profiles: Vertical profiles of wind, turbulence and temperature are created
See also
- Bibliography of atmospheric dispersion modeling
- Atmospheric dispersion modelingAtmospheric dispersion modelingAtmospheric dispersion modeling is the mathematical simulation of how air pollutants disperse in the ambient atmosphere. It is performed with computer programs that solve the mathematical equations and algorithms which simulate the pollutant dispersion...
- List of atmospheric dispersion models
Further reading
For those who are unfamiliar with air pollution dispersion modelling and would like to learn more about the subject, it is suggested that either one of the following books be read:www.crcpress.com www.air-dispersion.com
External links
- The EPA's download site for AERMOD (Model code, User's Guide and other material)
- Brode, R.W., Implementation and Evaluation of the AERMOD-PRIME Model (AMS Conference, May 21, 2002)