Atmospheric dispersion models are computer programs that use mathematical algorithms to simulate how pollutants in the ambient atmosphere disperse and, in some cases, how they react in the atmosphere.
Many of the dispersion models developed by or accepted for use by the U.S. Environmental Protection Agency (U.S. EPA) are accepted for use in many other countries as well. Those EPA models are grouped below into four categories.
These are models that are often used before applying a refined air quality model to determine if refined modelling is needed.
Photochemical air quality models have become widely utilized tools for assessing the effectiveness of control strategies adopted by regulatory agencies. These models are large-scale air quality models that simulate the changes of pollutant concentrations in the atmosphere by characterizing the chemical and physical processes in the atmosphere. These models are applied at multiple geographical scales ranging from local and regional to national and global.
The European Topic Centre on Air and Climate Change, which is part of the European Environment Agency (EEA), maintains an online Model Documentation System (MDS) that includes descriptions and other information for almost all of the dispersion models developed by the countries of Europe. The MDS currently (July 2012) contains 142 models, mostly developed in Europe. Of those 142 models, some were subjectively selected for inclusion here. Anyone interested in seeing the complete MDS can access it here.
Some of the European models listed in the MDS are public domain and some are not. Many of them include a pre-processor module for the input of meteorological and other data, and many also include a post-processor module for graphing the output data and/or plotting the area impacted by the air pollutants on maps.
The country of origin is included for each of the European models listed below.
The Air Resources Laboratory (ARL) is an air quality and climate laboratory in the Office of Oceanic and Atmospheric Research (OAR) which is an operating unit within the National Oceanic and Atmospheric Administration (NOAA) in the United States. It is one of seven NOAA Research Laboratories (RLs). In October 2005, the Surface Radiation Research Branch of the ARL was merged with five other NOAA labs to form the Earth System Research Laboratory.
Atmospheric dispersion modeling is the mathematical simulation of how air pollutants disperse in the ambient atmosphere. It is performed with computer programs that include algorithms to solve the mathematical equations that govern the pollutant dispersion. The dispersion models are used to estimate the downwind ambient concentration of air pollutants or toxins emitted from sources such as industrial plants, vehicular traffic or accidental chemical releases. They can also be used to predict future concentrations under specific scenarios. Therefore, they are the dominant type of model used in air quality policy making. They are most useful for pollutants that are dispersed over large distances and that may react in the atmosphere. For pollutants that have a very high spatio-temporal variability and for epidemiological studies statistical land-use regression models are also used.
Roadway air dispersion modeling is the study of air pollutant transport from a roadway or other linear emitter. Computer models are required to conduct this analysis, because of the complex variables involved, including vehicle emissions, vehicle speed, meteorology, and terrain geometry. Line source dispersion has been studied since at least the 1960s, when the regulatory framework in the United States began requiring quantitative analysis of the air pollution consequences of major roadway and airport projects. By the early 1970s this subset of atmospheric dispersion models was being applied to real-world cases of highway planning, even including some controversial court cases.
Germany has an air pollution control regulation titled "Technical Instructions on Air Quality Control" and commonly referred to as the TA Luft.
The National Atmospheric Release Advisory Center (NARAC) is located at the University of California's Lawrence Livermore National Laboratory. It is a national support and resource center for planning, real-time assessment, emergency response, and detailed studies of incidents involving a wide variety of hazards, including nuclear, radiological, chemical, biological, and natural emissions.
CALPUFF is an advanced, integrated Lagrangian puff modeling system for the simulation of atmospheric pollution dispersion distributed by the Atmospheric Studies Group at TRC Solutions.
PUFF-PLUME is a model used to help predict how air pollution disperses in the atmosphere. It is a Gaussian atmospheric transport chemical/radionuclide dispersion model that includes wet and dry deposition, real-time input of meteorological observations and forecasts, dose estimates from inhalation and gamma shine, and puff or continuous plume dispersion modes. It was first developed by the Pacific Northwest National Laboratory (PNNL) in the 1970s.
The ADMS 3 is an advanced atmospheric pollution dispersion model for calculating concentrations of atmospheric pollutants emitted both continuously from point, line, volume and area sources, or intermittently from point sources. It was developed by Cambridge Environmental Research Consultants (CERC) of the UK in collaboration with the UK Meteorological Office, National Power plc and the University of Surrey. The first version of ADMS was released in 1993. The version of the ADMS model discussed on this page is version 3 and was released in February 1999. It runs on Microsoft Windows. The current release, ADMS 5 Service Pack 1, was released in April 2013 with a number of additional features.
The AERMOD atmospheric dispersion modeling system is an integrated system that includes three modules:
NAME atmospheric pollution dispersion model was first developed by the UK's Met Office in 1986 after the nuclear accident at Chernobyl, which demonstrated the need for a method that could predict the spread and deposition of radioactive gases or material released into the atmosphere.
DISPERSION21 is a local scale atmospheric pollution dispersion model developed by the air quality research unit at Swedish Meteorological and Hydrological Institute (SMHI), located in Norrköping.
The following outline is provided as an overview of and topical guide to air pollution dispersion: In environmental science, air pollution dispersion is the distribution of air pollution into the atmosphere. Air pollution is the introduction of particulates, biological molecules, or other harmful materials into Earth's atmosphere, causing disease, death to humans, damage to other living organisms such as food crops, and the natural or built environment. Air pollution may come from anthropogenic or natural sources. Dispersion refers to what happens to the pollution during and after its introduction; understanding this may help in identifying and controlling it.
The Czech Hydrometeorological Institute is the central state office of the Czech Republic in the fields of air quality, meteorology, climatology and hydrology. It is an organization established by the Ministry of the Environment of the Czech Republic. The head office and centralized workplaces of the CHMI, including the data processing, telecommunication and technical services, are located at the Institute's own campus in Prague.
MERCURE is an atmospheric dispersion modeling CFD code developed by Électricité de France (EDF) and distributed by ARIA Technologies, a French company.
ISC3 (Industrial Source Complex) model is a popular steady-state Gaussian plume model which can be used to assess pollutant concentrations from a wide variety of sources associated with an industrial complex.
Austal2000 is an atmospheric dispersion model for simulating the dispersion of air pollutants in the ambient atmosphere. It was developed by Ingenieurbüro Janicke in Dunum, Germany under contract to the Federal Ministry for Environment, Nature Conservation and Nuclear Safety.
SAFE AIR is an advanced atmospheric pollution dispersion model for calculating concentrations of atmospheric pollutants emitted both continuously or intermittently from point, line, volume and area sources. It adopts an integrated Gaussian puff modeling system. SAFE AIR consists of three main parts: the meteorological pre-processor WINDS to calculate wind fields, the meteorological pre-processor ABLE to calculate atmospheric parameters and a lagrangian multisource model named P6 to calculate pollutant dispersion. SAFE AIR is included in the online Model Documentation System (MDS) of the European Environment Agency (EEA) and of the Italian Agency for the Protection of the Environment (APAT).
A chemical transport model (CTM) is a type of computer numerical model which typically simulates atmospheric chemistry and may give air pollution forecasting.
Turbulent diffusion is the transport of mass, heat, or momentum within a system due to random and chaotic time dependent motions. It occurs when turbulent fluid systems reach critical conditions in response to shear flow, which results from a combination of steep concentration gradients, density gradients, and high velocities. It occurs much more rapidly than molecular diffusion and is therefore extremely important for problems concerning mixing and transport in systems dealing with combustion, contaminants, dissolved oxygen, and solutions in industry. In these fields, turbulent diffusion acts as an excellent process for quickly reducing the concentrations of a species in a fluid or environment, in cases where this is needed for rapid mixing during processing, or rapid pollutant or contaminant reduction for safety.
The Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT) is a computer model that is used to compute air parcel trajectories to determine how far and in what direction a parcel of air, and subsequently air pollutants, will travel. HYSPLIT is also capable of calculating air pollutant dispersion, chemical transformation, and deposition. The HYSPLIT model was developed by the National Oceanic and Atmospheric Administration (NOAA) Air Resources Laboratory and the Australian Bureau of Meteorology Research Centere in 1998. The model derives its name from the usage of both Lagrangian and Eulerian approaches.
Schenk R (1996) Entwicklung von IBS Verkehr, Fördervorhaben des Ministeriums für Umwelt und Landwirtschaft des Landes Sachsen-Anhalt, FKZ 76213//95, 1996
Schenk R (1980) Numerische Behandlung instationärer Transportprobleme,Habilitation an der TU Dresden, 1980
For those who would like to learn more about atmospheric dispersion models, it is suggested that either one of the following books be read: