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Atmospheric dispersion models are computer programs that use mathematical
algorithm In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
s to simulate how pollutants in the ambient
atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A ...
disperse and, in some cases, how they react in the atmosphere.


US Environmental Protection Agency models

Many of the dispersion models developed by or accepted for use by the
U.S. Environmental Protection Agency The Environmental Protection Agency (EPA) is an Independent agencies of the United States government, independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon pro ...
(U.S. EPA) are accepted for use in many other countries as well. Those EPA models are grouped below into four categories.


Preferred and recommended models

*
AERMOD The AERMOD atmospheric dispersion modeling system is an integrated system that includes three modules:Prater, E.T. and Midgley, C., ''A new air dispersion modeling system is helping create more accurate industrial source models'', Environmental Prot ...
– An atmospheric dispersion model based on
atmospheric boundary layer In meteorology, the planetary boundary layer (PBL), also known as the atmospheric boundary layer (ABL) or peplosphere, is the lowest part of the atmosphere and its behaviour is directly influenced by its contact with a planetary surface. On Ear ...
turbulence structure and scaling concepts, including treatment of multiple ground-level and elevated point,
area Area is the quantity that expresses the extent of a region on the plane or on a curved surface. The area of a plane region or ''plane area'' refers to the area of a shape or planar lamina, while '' surface area'' refers to the area of an op ...
and volume sources. It handles flat or complex, rural or urban terrain and includes algorithms for building effects and plume penetration of inversions aloft. It uses Gaussian dispersion for stable atmospheric conditions (i.e., low turbulence) and non-Gaussian dispersion for unstable conditions (high turbulence). Algorithms for plume depletion by wet and dry deposition are also included in the model. This model was in development for approximately 14 years before being officially accepted by the U.S. EPA. *
CALPUFF __NOTOC__ 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. It is maintained by the model developers and distr ...
– A non-steady-state
puff Puff may refer to: Science and technology * Puff, a small quantity of gas or smoke in the air ** Puff, a light gust of wind ** Exhalation ** Inhalation * Puff model, volcanic ash tracking model developed at the University of Alaska Fairbanks * PUF ...
dispersion model that simulates the effects of time- and space-varying meteorological conditions on pollution transport, transformation, and removal. CALPUFF can be applied for long-range transport and for complex terrain. * BLP – A Gaussian plume dispersion model designed to handle unique modelling problems associated with industrial sources where plume rise and
downwash In aeronautics, downwash is the change in direction of air deflected by the aerodynamic action of an airfoil, wing, or helicopter rotor blade in motion, as part of the process of producing lift.Crane, Dale: ''Dictionary of Aeronautical Terms, thir ...
effects from stationary
line source A line source, as opposed to a point source, area source, or volume source, is a source of air, noise, water contamination or electromagnetic radiation that emanates from a linear (one-dimensional) geometry. The most prominent linear sources ...
s are important. * CALINE3 – A steady-state Gaussian dispersion model designed to determine pollution concentrations at receptor locations downwind of highways located in relatively uncomplicated terrain. * CAL3QHC and CAL3QHCR – CAL3QHC is a CALINE3 based model with queuing calculations and a traffic model to calculate delays and queues that occur at signalized intersections. CAL3QHCR is a more refined version based on CAL3QHC that requires local meteorological data. * CTDMPLUS – A complex terrain dispersion model (CTDM) plus algorithms for unstable situations (i.e., highly turbulent atmospheric conditions). It is a refined point source Gaussian air quality model for use in all stability conditions (i.e., all conditions of atmospheric turbulence) for complex terrain. *OCD – Offshore and coastal dispersion model (OCD) is a Gaussian model developed to determine the impact of offshore emissions from point, area or line sources on the air quality of coastal regions. It incorporates overwater plume transport and dispersion as well as changes that occur as the plume crosses the shoreline.


Alternative models

* ADAM – Air force dispersion assessment model (ADAM) is a modified box and Gaussian dispersion model which incorporates thermodynamics, chemistry, heat transfer, aerosol loading, and dense gas effects. *
ADMS 3 The ADMS 3 (Atmospheric Dispersion Modelling System) is an advanced atmospheric pollution dispersion model for calculating concentrations of atmospheric pollutants emitted both continuously from point, line, volume and area sources, or intermit ...
– Atmospheric dispersion modelling system (ADMS 3) is an advanced dispersion model developed in the United Kingdom for calculating concentrations of pollutants emitted both continuously from point, line, volume and area sources, or discretely from point sources. * AFTOX – A Gaussian dispersion model that handles continuous or puff, liquid or gas, elevated or surface releases from point or area sources. * DEGADIS – Dense gas dispersion (DEGADIS) is a model that simulates the dispersion at ground level of area source clouds of denser-than-air gases or aerosols released with zero momentum into the atmosphere over flat, level terrain. * HGSYSTEM – A collection of computer programs developed by Shell Research Ltd. and designed to predict the source-term and subsequent dispersion of accidental chemical releases with an emphasis on dense gas behavior. * HOTMAC and RAPTAD – HOTMAC is a model for weather forecasting used in conjunction with RAPTAD which is a puff model for pollutant transport and dispersion. These models are used for complex terrain, coastal regions, urban areas, and around buildings where other models fail. * HYROAD – The hybrid roadway model integrates three individual modules simulating the pollutant emissions from vehicular traffic and the dispersion of those emissions. The dispersion module is a puff model that determines concentrations of carbon monoxide (CO) or other gaseous pollutants and particulate matter (PM) from vehicle emissions at receptors within 500 meters of the roadway intersections. * ISC3 – A Gaussian model used to assess pollutant concentrations from a wide variety of sources associated with an industrial complex. This model accounts for: settling and dry deposition of particles; downwash; point, area, line, and volume sources; plume rise as a function of downwind distance; separation of point sources; and limited terrain adjustment. ISC3 operates in both long-term and short-term modes. * OBODM – A model for evaluating the air quality impacts of the open burning and detonation (OB/OD) of obsolete munitions and solid propellants. It uses dispersion and deposition algorithms taken from existing models for instantaneous and quasi-continuous sources to predict the transport and dispersion of pollutants released by the open burning and detonation operations. * PANACHE – Fluidyn-PANACHE is an Eulerian (and Lagrangian for particulate matter), 3-dimensional finite volume fluid mechanics model designed to simulate continuous and short-term pollutant dispersion in the atmosphere, in simple or complex terrain. * PLUVUEII – A model that estimates atmospheric visibility degradation and atmospheric discoloration caused by plumes resulting from the emissions of particles, nitrogen oxides, and sulfur oxides. The model predicts the transport, dispersion, chemical reactions, optical effects and surface deposition of such emissions from a single point or area source. * SCIPUFF – A puff dispersion model that uses a collection of Gaussian puffs to predict three-dimensional, time-dependent pollutant concentrations. In addition to the average concentration value, SCIPUFF predicts the statistical variance in the concentrations resulting from the random fluctuations of the wind. * SDM – Shoreline dispersion model (SDM) is a Gaussian dispersion model used to determine ground-level concentrations from tall stationary point source emissions near a shoreline. * SLAB – A model for denser-than-air gaseous plume releases that utilizes the one-dimensional equations of momentum, conservation of mass and energy, and the equation of state. SLAB handles point source ground-level releases, elevated jet releases, releases from volume sources and releases from the evaporation of volatile liquid spill pools.


Screening models

These are models that are often used before applying a refined air quality model to determine if refined modelling is needed. * AERSCREEN – The screening version of AERMOD. It produces estimates of concentrations, without the need for meteorological data, that are equal to or greater than the estimates produced by AERMOD with a full set of meteorological data. The U.S. EPA released version 11060 of AERSCREEN on 11 March 2010 with a subsequent update, version 11076, on 17 March 2010. The U.S. EPA published the "Clarification memorandum on AERSCREEN as the recommended screening model" on 11 April 2011. * CTSCREEN – The screening version of CTDMPLUS. * SCREEN3 – The screening version of ISC3. * TSCREEN – Toxics screening model (TSCREEN) is a Gaussian model for screening toxic air pollutant emissions and their subsequent dispersion from possible releases at
superfund sites Superfund sites are polluted locations in the United States requiring a long-term response to clean up hazardous material contaminations. They were designated under the Comprehensive Environmental Response, Compensation, and Liability Act (CERC ...
. It contains 3 modules: SCREEN3, PUFF, and RVD (Relief Valve Discharge). * VALLEY – A screening, complex terrain, Gaussian dispersion model for estimating 24-hour or annual concentrations resulting from up to 50 point and area emission sources. * COMPLEX1 – A multiple point source screening model with terrain adjustment that uses the plume impaction algorithm of the VALLEY model. * RTDM3.2 – Rough terrain diffusion model (RTDM3.2) is a Gaussian model for estimating ground-level concentrations of one or more co-located point sources in rough (or flat) terrain. * VISCREEN – A model that calculates the impact of specified emissions for specific transport and dispersion conditions.


Photochemical Photochemistry is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemical reaction caused by absorption of ultraviolet (wavelength from 100 to 400  nm), visible light (400–7 ...
models

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. * Models-3/CMAQ – The latest version of the community multi-scale air quality (CMAQ) model has state-of-the-science capabilities for conducting urban to regional scale simulations of multiple air quality issues, including tropospheric ozone, fine particles, toxics, acid deposition, and visibility degradation. * CAMx – The comprehensive air quality model with extensions (CAMx) simulates air quality over many geographic scales. It handles a variety of inert and chemically active pollutants, including ozone, particulate matter, inorganic and organic PM2.5/PM10, and mercury and other toxics. * REMSAD – The regional modeling system for aerosols and deposition (REMSAD) calculates the concentrations of both inert and chemically reactive pollutants by simulating the atmospheric processes that affect pollutant concentrations over regional scales. It includes processes relevant to regional haze, particulate matter and other airborne pollutants, including soluble acidic components and mercury. * UAM-V – The urban airshed model was a pioneering effort in photochemical air quality modelling in the early 1970s and has been used widely for air quality studies focusing on ozone.


Other models developed in the United States

* CHARM – A model capable of simulating dispersion of toxics and particles. It can calculate impacts of thermal radiation from fires, overpressures from mechanical failures and explosions, and nuclear radiation from radionuclide releases. CHARM is capable of handling effects of complex terrain and buildings. A Lagrangian puff screening version and Eulerian full-function version are available. More information is availabl
here
* HYSPLIT – Hybrid Single Particle Lagrangian Integrated Trajectory Model. Developed at NOAA's Air Resources Laboratory. The HYSPLIT model is a complete system for computing simple air parcel trajectories to complex dispersion and deposition simulations. More information about this model can be found a

* PUFF-PLUME – A Gaussian 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 plume dispersion modes. It is the primary model for emergency response use for atmospheric releases of radioactive materials at the
Savannah River Site The Savannah River Site (SRS) is a U.S. Department of Energy (DOE) reservation in the United States in the state of South Carolina, located on land in Aiken, Allendale, and Barnwell counties adjacent to the Savannah River, southeast of August ...
of the
United States Department of Energy The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and manages the research and development of nuclear power and nuclear weapons in the United States ...
. It was first developed by the
Pacific Northwest National Laboratory Pacific Northwest National Laboratory (PNNL) is one of the United States Department of Energy national laboratories, managed by the Department of Energy's (DOE) Office of Science. The main campus of the laboratory is in Richland, Washington. ...
(PNNL) in the 1970s. *
Puff model The Puff model is a volcanic ash tracking model developed at the University of Alaska Fairbanks. It requires windfield data on a geographic grid covering the area over which ash may be dispersed. Representative ash particles are initiated at the vol ...
– Puff is a volcanic ash tracking model developed at the
University of Alaska Fairbanks The University of Alaska Fairbanks (UAF or Alaska) is a public land-grant research university in College, Alaska, a suburb of Fairbanks. It is the flagship campus of the University of Alaska system. UAF was established in 1917 and opened for c ...
. It requires NWP wind field data on a geographic grid covering the area over which ash may be dispersed. Representative ash particles are initiated at the volcano's location and then allowed to advect, diffuse, and settle within the atmosphere. The location of the particles at any time after the eruption can be viewed using the post-processing software included with the model. Output data is in netCDF format and can also be viewed with a variety of software. More information on the model is availabl
here.


Models developed in the United Kingdom

* ADMS-3 – See the description of this model in the alternative models section of the models accepted by the U.S. EPA. * ADMS-URBAN – A model for simulating dispersion on scales ranging from a street scale to citywide or county-wide scale, handling most relevant emission sources such as traffic, industrial, commercial, and domestic sources. It is also used for air quality management and assessments of current and future air quality vis-a-vis national and regional standards in Europe and elsewhere. * ADMS-Roads – A model for simulating dispersion of vehicular pollutant emissions from small road networks in combination with emissions from industrial plants. It handles multiple road sources as well as multiple point, line or area emission sources and the model operation is similar to the other ADMS models * ADMS-Screen – A screening model for rapid assessment of the air quality impact of a single industrial stack to determine if more detailed modelling is needed. It combines the dispersion modelling algorithms of the ADMS models with a user interface requiring minimal input data. * GASTAR – A model for simulating accidental releases of denser-than-air flammable and toxic gases. It handles instantaneous and continuous releases, releases from jet sources, releases from evaporation of volatile liquid pools, variable terrain slopes and ground roughness, obstacles such as fences and buildings, and time-varying releases. *
NAME A name is a term used for identification by an external observer. They can identify a class or category of things, or a single thing, either uniquely, or within a given context. The entity identified by a name is called its referent. A persona ...
– Numerical atmospheric-dispersion modelling environment (NAME) is a local to global scale model developed by the UK's
Met Office The Meteorological Office, abbreviated as the Met Office, is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy and is led by CEO Penelop ...
. It is used for: forecasting of air quality, air pollution dispersion, and acid rain; tracking
radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consi ...
emissions and volcanic ash discharges; analysis of accidental air pollutant releases and assisting in emergency response; and long-term environmental impact analysis. It is an integrated model that includes boundary layer dispersion modelling. * UDM – Urban dispersion model is a Gaussian puff based model for predicting the dispersion of atmospheric pollutants in the range of 10m to 25 km throughout the urban environment. It is developed by the Defense Science and Technology Laboratory for the UK Ministry of Defence. It handles instantaneous, continuous, and pool releases, and can model gases, particulates, and liquids. The model has a three regime structure: that of single building (area density < 5%), urban array (area density > 5%) and open. The model can be coupled with the US model SCIPUFF to replace the open regime and extend the model's prediction range.


Models developed in continental Europe

The European Topic Centre on Air and Climate Change, which is part of the
European Environment Agency The European Environment Agency (EEA) is the agency of the European Union (EU) which provides independent information on the environment. Definition The European Environment Agency (EEA) is the agency of the European Union (EU) which provides ...
(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 i
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. * AEROPOL (Estonia) – The AERO-POLlution model developed at the Tartu Observatory in Estonia is a Gaussian plume model for simulating the dispersion of continuous, buoyant plumes from stationary point, line and area sources over flat terrain on a local to regional scale. It includes plume depletion by wet and/or dry deposition as well as the effects of buildings in the plume path. * Airviro Gauss (Sweden) – A gaussian dispersion model that handles point, road, area and grid sources developed by
SMHI The Swedish Meteorological and Hydrological Institute ( sv, Sveriges meteorologiska och hydrologiska institut, abbreviated SMHI) is a Government agency in Sweden and operates under the Ministry of the Environment. SMHI has expertise within the a ...
. Plumes follow trajectories from a wind model and each plume has a cutoff dependent on wind speed. The model also support irregular calculation grids. * Airviro Grid (Sweden) – A simplified eulerian model developed by
SMHI The Swedish Meteorological and Hydrological Institute ( sv, Sveriges meteorologiska och hydrologiska institut, abbreviated SMHI) is a Government agency in Sweden and operates under the Ministry of the Environment. SMHI has expertise within the a ...
. Can handle point, road, area and grid sources. Includes dry and wet deposition and sedimentation. * Airviro Heavy Gas (Sweden) – A model for heavy gas dispersion developed by
SMHI The Swedish Meteorological and Hydrological Institute ( sv, Sveriges meteorologiska och hydrologiska institut, abbreviated SMHI) is a Government agency in Sweden and operates under the Ministry of the Environment. SMHI has expertise within the a ...
. * Airviro receptor model (Sweden)- An inverse dispersion model developed by
SMHI The Swedish Meteorological and Hydrological Institute ( sv, Sveriges meteorologiska och hydrologiska institut, abbreviated SMHI) is a Government agency in Sweden and operates under the Ministry of the Environment. SMHI has expertise within the a ...
. Used to find emission sources. * ATSTEP (Germany) – Gaussian puff dispersion and deposition model used in the decision support system RODOS (real-time on-line decision support) for nuclear emergency management. RODOS is operational in Germany by the Federal Office for Radiation Protection (BfS) and test-operational in many other European countries. More information on RODOS is available here and on the ATSTEP model here. *
AUSTAL2000 Austal2000 is an atmospheric dispersion model for simulating the dispersion of air pollutants in the ambient atmosphere. It was developed by Ingenieurbüro Janicke
(Germany) – The official air dispersion model to be used in the permitting of industrial sources by the German Federal Environmental Agency. The model accommodates point, line, area and volume sources of buoyant plumes. It has capabilities for building effects, complex terrain, plume depletion by wet or dry deposition, and first order chemical reactions. It is based on the LASAT model developed by Ingenieurbüro Janicke Gesellschaft für Umweltphysik. * BUO-FMI (Finland) – This model was developed by the Finnish Meteorological Institute (FMI) specifically for estimating the atmospheric dispersion of neutral or buoyant plume gases and particles emitted from fires in warehouses and chemical stores. It is a hybrid of a local scale Gaussian plume model and another model type. Plume depletion by dry deposition is included but wet deposition is not included. * CAR-FMI (Finland) – This model was developed by the Finnish Meteorological Institute (FMI) for evaluating atmospheric dispersion and chemical transformation of vehicular emissions of inert (CO, NOx) and reactive (NO, NO2, O3) gases from a road network of line sources on a local scale. It is a Gaussian line source model which includes an analytical solution for the chemical cycle NO-O3-NO2. * CAR-International (The Netherlands) – Calculation of air pollution from road traffic (CAR-International) is an atmospheric dispersion model developed by the
Netherlands Organisation for Applied Scientific Research Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek (TNO; en, Netherlands Organisation for Applied Scientific Research) is an independent research organisation in the Netherlands that focuses on applied science. The organisat ...
. It is used for simulating the dispersion of vehicular emissions from roadway traffic. * DIPCOT (Greece) – Dispersion over complex terrain (DIPCOT) is a model developed in the
National Centre of Scientific Research "DEMOKRITOS" The National Centre of Scientific Research "Demokritos" (NRCPS; el, Εθνικό Κέντρο Έρευνας Φυσικών Επιστημών (Ε.Κ.Ε.Φ.Ε.) "Δημόκριτος") is a research center in Greece, employing over 1,000 researc ...
of Greece that simulates dispersion of buoyant plumes from multiple point sources over complex terrain on a local to regional scale. It does not include wet deposition or chemical reactions. *
DISPERSION21 DISPERSION21 (also called DISPERSION 2.1) 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 model is widely ...
(Sweden) – This model was developed by the
Swedish Meteorological and Hydrological Institute The Swedish Meteorological and Hydrological Institute ( sv, Sveriges meteorologiska och hydrologiska institut, abbreviated SMHI) is a Government agency in Sweden and operates under the Ministry of the Environment. SMHI has expertise within the a ...
(SMHI) for evaluating air pollutant emissions from existing or planned industrial or urban sources on a local scale. It is a Gaussian plume model for point, area, line and vehicular traffic sources. It includes plume penetration of inversions aloft, building effects, NOx chemistry and it can handle street canyons. It does not include wet or dry deposition, complex atmospheric chemistry, or the effects of complex terrain. * DISPLAY-2 (Greece) – A vapour cloud dispersion model for neutral or denser-than-air pollution plumes over irregular, obstructed terrain on a local scale. It accommodates jet releases as well as two-phase (i.e., liquid-vapor mixtures) releases. This model was also developed at the National Centre of Scientific Research "DEMOKRITOS" of Greece. * EK100W (Poland) – A Gaussian plume model used for air quality impact assessments of pollutants from industrial point sources as well as for urban air quality studies on a local scale. It includes wet and dry deposition. The effects of complex terrain are not included. * FARM (Italy) – The Flexible Air quality Regional Model (FARM) is a multi-grid Eulerian model for dispersion, transformation and deposition of airborne pollutants in gas and aerosol phases, including photo-oxidants, aerosols, heavy metals and other toxics. It is suited for case studies, air quality assessments, scenarios analyses and pollutants forecast. * FLEXPART (Austria/Germany/Norway) – An efficient and flexible Lagrangian particle transport and diffusion model for regional to global applications, with capability for forward and backward mode. Freely available. Developed at BOKU Vienna,
Technical University of Munich The Technical University of Munich (TUM or TU Munich; german: Technische Universität München) is a public research university in Munich, Germany. It specializes in engineering, technology, medicine, and applied science, applied and Natural sci ...
, and
NILU The NILU – Norwegian Institute for Air Research ( no, NILU – Norsk Institutt for luftforskning) or NILU is one of the leading specialized scientific laboratories in Europe researching issues related to air pollution, climate change and health ...
. * GRAL (Austria) – The GRAz Lagrangian model was initially developed at the
Graz University of Technology Graz University of Technology (german: link=no, Technische Universität Graz, short ''TU Graz'') is one of five universities in Styria, Austria. It was founded in 1811 by Archduke John of Austria and is the oldest science and technology research ...
and it is a dispersion model for buoyant plumes from multiple point, line, area and tunnel portal sources. It handles flat or complex terrain (mesoscale prognostic flow field model) including building effects (microscale prognostic flow field model) but it has no chemistry capabilities. The model is freely available: http://lampz.tugraz.at/~gral/ * HAVAR (Czech Republic) – A Gaussian plume model integrated with a puff model and a hybrid plume-puff model, developed by the
Czech Academy of Sciences The Czech Academy of Sciences (abbr. CAS, cs, Akademie věd České republiky, abbr. AV ČR) was established in 1992 by the Czech National Council as the Czech successor of the former Czechoslovak Academy of Sciences and its tradition goes back ...
, is intended for routine and/or accidental releases of
radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transfer ...
s from single point sources within nuclear power plants. The model includes radioactive plume depletion by dry and wet deposition as well as by
radioactive decay Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...
. For the decay of some nuclides, the creation of daughter products that then grow into the plume is taken into account. * IFDM (Belgium) – The immission frequency distribution model, developed at the Flemish Institute for Technological Research (VITO), is a Gaussian dispersion model used for point and area sources dispersing over flat terrain on a local scale. The model includes plume depletion by dry or wet deposition and has been updated to handle building effects and the O3-NOx-chemistry. It is not designed for complex terrain or other chemically reactive pollutants. * INPUFF-U (Romania) – This model was developed by the National Institute of Meteorology and Hydrology in Bucharest, Romania. It is a Gaussian puff model for calculating the dispersion of radionuclides from passive emission plumes on a local to urban scale. It can simulate accidental or continuous releases from stationary or mobile point sources. It includes wet and dry deposition. Building effects, buoyancy effects, chemical reactions and effects of complex terrain are not included. * LAPMOD (Italy) – The LAPMOD (LAgrangian Particle MODel) modeling system is developed by Enviroware and it is available for free. LAPMOD is a Lagrangian partile model fully coupled to the diagnostic meteorological model CALMET and can be used to simulate the dispersion of inert pollutants as well as odors and radioactive substances. It includes dry and wet deposition algorithms and advanced numerical schemes for plume rise (Janicke and Janicke, Webster and Thomson). It can simulate inert pollutants, odors and radioactive substances and it is part of ARIES, the official Italian modeling system for nuclear emergencies operated by ISPRA and by the regional environmental protection agency of Emilia-Romagna, Italy. * LOTOS-EUROS (The Netherlands) – the long term ozone simulation – European operational smog (LOTOS-EUROS) model was developed by the
Netherlands Organisation for Applied Scientific Research Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek (TNO; en, Netherlands Organisation for Applied Scientific Research) is an independent research organisation in the Netherlands that focuses on applied science. The organisat ...
(TNO) and
Netherlands National Institute for Public Health and the Environment The National Institute for Public Health and the Environment ( nl, Rijksinstituut voor Volksgezondheid en Milieu or simply RIVM) is a Dutch research institute that is an independent agency of the Ministry of Health, Welfare and Sport. RIVM perfo ...
(RIVM) in The Netherlands. It is designed for modelling the dispersion of pollutants (such as: photo-oxidants, aerosols, heavy metals) over all of Europe. It includes simple reaction chemistry as well as wet and dry deposition. * MATCH (Sweden) – A multi-scale atmospheric transport and chemistry (MATCH). A three-dimensional, Eulerian model, suitable from urban to global scale. * MEMO (Greece) – A Eulerian non-hydrostatic prognostic mesoscale model for wind flow simulation. It was developed by the Aristotle University of Thessaloniki in collaboration with the
Universität Karlsruhe The Karlsruhe Institute of Technology (KIT; german: Karlsruher Institut für Technologie) is a public research university in Karlsruhe, Germany. The institute is a national research center of the Helmholtz Association. KIT was created in 2009 ...
. This model is designed for describing atmospheric transport phenomena in the local-to-regional scale, often referred to as mesoscale air pollution models. *
MERCURE Mercure may refer to: * MERCURE, an atmospheric dispersion modelling CFD code developed by Électricité de France * Mercure Hotels, a chain of hotels run by Accor * French ship Mercure (1783), French ship ''Mercure'' (1783) * Dassault Mercure, a ...
(France) – An atmospheric dispersion modeling CFD code developed by Electricite de France (EDF) and distributed by ARIA Technologies, a French company. The code is a version of the CFD software ESTET, developed by EDF's Laboratoire National d'Hydraulique. * MODIM (Slovak Republic) – A model for calculating the dispersion of continuous, neutral or buoyant plumes on a local to regional scale. It integrates a Gaussian plume model for single or multiple point and area sources with a numerical model for line sources, street networks and street canyons. It is intended for regulatory and planning purposes. * MSS (France) – Micro-swift-spray is a Lagrangian particle model used to predict the transport and dispersion of contaminants in urban environments. The SWIFT portion of this model predicts a mass-consistent wind field that considers terrain; no-penetration conditions for building boundaries; Rockle zones for recirculation, edge, and rooftop separation; and background and locally generated turbulence. The spray portion of the tool handles the dispersion of passive gases, dense gases, and particulates. Spray also accounts for plume buoyancy effects, wet and dry depositions, and calculates microscale pressure fields for integration with building models. The MSS development team is found at ARIA Technologies (France) and U.S. integration activities are led by Leidos. Validation testing of MSS has been done in conjunction with JEM and HPAC tool releases and the model is coupled with SCIPUFF/UDM to create a nested dispersion capability inside HPAC. For more information on MSS see http://www.aria.fr. * MUSE (Greece) – A photochemical atmospheric dispersion model developed by Professor Nicolas Moussiopoulos at the
Aristotle University of Thessaloniki Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of phil ...
in Greece. It is intended for the study of photochemical smog formation in urban areas and assessment of control strategies on a local to regional scale. It can simulate dry deposition and transformation of pollutants can be treated using any suitable chemical reaction mechanism. * OML (Denmark) – A model for dispersion calculations of continuous neutral or buoyant plumes from single or multiple, stationary point and area sources. It has some simple methods for handling photochemistry (primarily for NO2) and for handling complex terrain. The model was developed by the
National Environmental Research Institute of Denmark The National Environmental Research Institute of Denmark, abbreviated NERI, ( da, Danmarks Miljøundersøgelser, abbreviated DMU) was an independent research institute under the Ministry of the Environment. It was created in 1989 by merging the e ...
. It is now maintained by the Department of Environmental Science,
Aarhus University Aarhus University ( da, Aarhus Universitet, abbreviated AU) is a public research university with its main campus located in Aarhus, Denmark. It is the second largest and second oldest university in Denmark. The university is part of the Coimbra Gr ...
. For further reference see as well
OML home page
* ONM9440 (Austria) – A Gaussian dispersion model for continuous, buoyant plumes from stationary sources for use in flat terrain areas. It includes plume depletion by dry deposition of solid particulates. * OSPM (Denmark) – The operational street pollution model (OSPM) is a practical street pollution model, developed by the
National Environmental Research Institute of Denmark The National Environmental Research Institute of Denmark, abbreviated NERI, ( da, Danmarks Miljøundersøgelser, abbreviated DMU) was an independent research institute under the Ministry of the Environment. It was created in 1989 by merging the e ...
. It is now maintained by the Department of Environmental Science,
Aarhus University Aarhus University ( da, Aarhus Universitet, abbreviated AU) is a public research university with its main campus located in Aarhus, Denmark. It is the second largest and second oldest university in Denmark. The university is part of the Coimbra Gr ...
. For almost 20 years, OSPM has been routinely used in many countries for studying traffic pollution, performing analyses of field campaign measurements, studying efficiency of pollution abatement strategies, carrying out exposure assessments and as reference in comparisons to other models. OSPM is generally considered as state-of-the-art in applied street pollution modelling. For further reference see as well
OSPM home page
* PANACHE (France) – fluidyn-PANACHE is a self-contained fully 3D fluid dynamics software package designed to simulate accidental or continuous industrial and urban pollutant dispersion into the atmosphere. It simulates release and toxic/flammables pollutants dispersion in various weather conditions in calculated 3D complex winds and turbulence fields. Gas, particles, droplets induced flow and transport/diffusion is simulated with Navier-Stokes equations for jet-like, dense, cold, cryogenic or hot, buoyant releases. The application covers the very short scale (tens of meters) and the local scale (ten kilometers) where the complex flow pattern as related to obstacles, variable land uses, topography is calculated explicitly. * PROKAS-V (Germany) – A Gaussian dispersion model for evaluating the atmospheric dispersion of air pollutants emitted from vehicular traffic on a road network of line sources on a local scale.
PLUME (Bulgaria)
– A conventional Gaussian plume model used in many regulatory applications. The basis of the model is a single simple formula which assumes constant wind speed and reflection from the ground surface. The horizontal and vertical dispersion parameters are a function of downwind distance and stability. The model was developed for routine applications in air quality assessment, regulatory purposes and policy support. * POLGRAPH (Portugal) – This model was developed at the University of Aveiro, Portugal by Professor Carlos Borrego. It was designed for evaluating the impact of industrial pollutant releases and for air quality assessments. It is a Gaussian plume dispersion model for continuous, elevated point sources to be used on a local scale over flat or gently rolling terrain. * RADM (France) – The random-walk advection and dispersion model (RADM) was developed by ACRI-ST, an independent research and development organization in France. It can model gas plumes and particles (including pollutants with exponential decay or formation rates) from single or multiple stationary, mobile or area sources. Chemical reaction, radioactive decay, deposition, complex terrain, and inversion conditions are accommodated. * RIMPUFF (Denmark) – A local and regional scale real-time puff diffusion model developed by Risø National Laboratory for Sustainable Energy, Technical University of Denmark. Risø DTU. RIMPUFF is an operational emergency response model in use for assisting emergency management organisations dealing with chemical, nuclear, biological and radiological (CBRN) releases to the atmosphere. RIMPUFF is in operation in several European national emergency centres for preparedness and prediction of nuclear accidental releases (RODOS, EURANOS, ARGOS), chemical gas releases ( ARGOS), and serves also as a decision support tool during active combatting of airborne transmission of various biological infections, including e.g. Foot-and Mouth Disease outbreaks. DEFRA Foot and Mouth Disease. * SAFE AIR II (Italy) – The simulation of air pollution from emissions II (SAFE AIR II) was developed at the Department of Physics,
University of Genoa The University of Genoa, known also with the acronym UniGe ( it, Università di Genova), is one of the largest universities in Italy. It is located in the city of Genoa and regional Metropolitan City of Genoa, on the Italian Riviera in the Ligur ...
, Italy to simulate the dispersion of air pollutants above complex terrain at local and regional scales. It can handle point, line, area and volume sources and continuous plumes as well as puffs. It includes first-order chemical reactions and plume depletion by wet and dry deposition, but it does not include any photochemistry. * SEVEX (Belgium) – The Seveso expert model simulates the accidental release of toxic and/or flammable material over flat or complex terrain from multiple pipe and vessel sources or from evaporation of volatile liquid spill pools. The accidental releases may be continuous, transient or catastrophic. The integrated model can handle denser-than-air gases as well as neutral gases (i.e., neither denser than or lighter than air). It does not include handling of multi-component material, nor does it provide for chemical transformation of the releases. The model's name is derived from the major disaster caused by the accidental release of highly toxic gases that occurred in
Seveso Seveso (; lmo, label= Lombard, Séves ) is a town and ''comune'' in the Province of Monza and Brianza, in the Region of Lombardy. The economy of the town has traditionally been based on the furniture industry. Its name comes from the river of ...
, Italy in 1976. * SPRAY (Italy, France) SPRAY publications
/ref> – A Lagrangian particle dispersion model (LPDM) which simulates the transport, dispersion and deposition of pollutants emitted from sources of different kind over complex terrain and with the presence of obstacles. The model easily takes into account complex situations, such as the presence of breeze cycles, strong meteorological inhomogeneities and non-stationary, low wind calm conditions and recirculations. Simulations can cover area ranging from very local (less than one kilometer) to regional (hundreds of kilometres) scales. Plume rise of hot emission from stack is taken into account using a Briggs formulation. Algorithms for particle-oriented dry/wet deposition processes and for considering the gravitational settling are present. Dry deposition can be computed on ground and also on ceil/roof and on lateral faces of obstacles. Dispersion under generalized geometries like arches, tunnels and walkways can be performed. Dense gas dispersion is simulated using five conservation equations (mass, energy, vertical momentum and two horizontal momenta) based on Glandening et al. (1984) and Hurley and Manins (1995). Plume spread at the ground due to gravity is also simulated by a method (Anfossi et al., 2009), based on Eidsvik (1980). * STACKS (The Netherlands) – A Gaussian plume dispersion model for point and area buoyant plumes to be used over flat terrain on a local scale. It includes building effects, NO2 chemistry and plume depletion by deposition. It is used for environmental impact studies and evaluation of emission reduction strategies. * STOER.LAG (Germany) – A dispersion model designed to evaluate accidental releases of hazardous and/or flammable materials from point or area sources in industrial plants. It can handle neutral and denser-than-air gases or aerosols from ground-level or elevated sources. The model accommodates building and terrain effects, evaporation of volatile liquid spill pools, and combustion or explosion of flammable gas-air mixtures (including the impact of heat and pressure waves caused by a fire or explosion). * SYMOS'97 (Czech Republic) – A model developed by the
Czech Hydrometeorological Institute The Czech Hydrometeorological Institute (CHMI; cs, Český hydrometeorologický ústav (ČHMÚ)) is the central state office of the Czech Republic in the fields of air quality, meteorology, climatology and hydrology. It is an organization establ ...
for dispersion calculations of continuous neutral or buoyant plumes from single or multiple point, area or line sources. It can handle complex terrain and it can also be used to simulate the dispersion of
cooling tower A cooling tower is a device that rejects waste heat to the atmosphere through the cooling of a coolant stream, usually a water stream to a lower temperature. Cooling towers may either use the evaporation of water to remove process heat an ...
plumes. * TCAM is a multiphase three-dimensional eulerian grid model designed by ESMA group of University of Brescia, for modelling dispersion of pollutants (in particular photochemical and aerosol) at mesoscale. * UDM-FMI (Finland) – This model was developed by the Finnish Meteorological Institute (FMI) as an integrated Gaussian urban scale model intended for regulatory pollution control. It handles multiple point, line, area and volume sources and it includes chemical transformation (for NO2), wet and dry deposition (for SO2), and downwash phenomena (but no building effects). * VANADIS (Poland) – 3D unsteady state eulerian type mode
– Demo – 3d dispersion model
– please read vanadis_eng.txt.


Models developed in Australia

* AUSPLUME – A dispersion model that has been designated as the primary model accepted by the Environmental Protection Authority (EPA) of the Australian state of Victoria. (update:AUSPLUME V6 will no longer be the air pollution dispersion regulatory model in Victoria from 1 January 2014. From this date the air pollution dispersion regulatory model in Victoria will be AERMOD.) * pDsAUSMOD – Australian graphical user interface for AERMOD * pDsAUSMET – Australian meteorological data processor for AERMOD *LADM – An advanced model developed by Australia's
Commonwealth Scientific and Industrial Research Organisation The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Government agency responsible for scientific research. CSIRO works with leading organisations around the world. From its headquarters in Canberra, CSIRO ...
(CSIRO) for simulating the dispersion of buoyant pollution plumes and predicting the photochemical formation of smog over complex terrain on a local to regional scale. The model can also handle fumigated plumes (see the books listed below in the "Further reading" section for an explanation of fumigated plumes). * TAPM – An advanced dispersion model integrated with a pre-processor for providing meteorological data inputs. It can handle multiple pollutants, and point, line, area and volume sources on a local, city or regional scale. The model capabilities include building effects, plume depletion by deposition, and a photochemistry module. This model was also developed by Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO). * DISPMOD – A Gaussian atmospheric dispersion model for point sources located in coastal regions. It was designed specifically by the Western Australian Department of Environment to simulate the plume fumigation that occurs when an elevated onshore pollution plume intersects a growing thermal internal boundary layer (TIBL) contained within offshore air flow coming onshore. * AUSPUFF – A Gaussian puff model designed for regulatory use by CSIRO. It includes some simple algorithms for the chemical transformation of reactive air pollutants.


Models developed in Canada

* MLCD – ''Modèle Lagrangien à courte distance'' is a
Lagrangian Lagrangian may refer to: Mathematics * Lagrangian function, used to solve constrained minimization problems in optimization theory; see Lagrange multiplier ** Lagrangian relaxation, the method of approximating a difficult constrained problem with ...
particle dispersion model (LPDM) developed in collaboration by
Environment Canada Environment and Climate Change Canada (ECCC; french: Environnement et Changement climatique Canada),Environment and Climate Change Canada is the applied title under the Federal Identity Program; the legal title is Department of the Environment ...
's
Canadian Meteorological Centre The Canadian Meteorological Centre (CMC; french: Centre météorologique canadien), located in Dorval, Quebec, is the branch of Environment Canada's Meteorological Service of Canada that is tasked with providing forecast guidance to national ...
(CMC) and by the Department of Earth and Atmospheric Sciences of
University of Alberta The University of Alberta, also known as U of A or UAlberta, is a Public university, public research university located in Edmonton, Alberta, Canada. It was founded in 1908 by Alexander Cameron Rutherford,"A Gentleman of Strathcona – Alexande ...
. This atmospheric dispersion and deposition model is designed to estimate air concentrations and surface deposition of pollutants for very short range emergency problems (less than ~10 km from the source). * MLDPn – ''Modèle Lagrangien de dispersion de particules d'ordre n'' is a
Lagrangian Lagrangian may refer to: Mathematics * Lagrangian function, used to solve constrained minimization problems in optimization theory; see Lagrange multiplier ** Lagrangian relaxation, the method of approximating a difficult constrained problem with ...
particle dispersion model (LPDM) developed by
Environment Canada Environment and Climate Change Canada (ECCC; french: Environnement et Changement climatique Canada),Environment and Climate Change Canada is the applied title under the Federal Identity Program; the legal title is Department of the Environment ...
's
Canadian Meteorological Centre The Canadian Meteorological Centre (CMC; french: Centre météorologique canadien), located in Dorval, Quebec, is the branch of Environment Canada's Meteorological Service of Canada that is tasked with providing forecast guidance to national ...
(CMC). This atmospheric and aquatic transport and dispersion model is designed to estimate air and water concentrations and ground deposition of pollutants for various emergency response problems at different scales (local to global). It is used to forecast and track
volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer ...
,
radioactive material A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...
, forest fire smoke, chemical hazardous substances as well as
oil slick An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially the marine ecosystem, due to human activity, and is a form of pollution. The term is usually given to marine oil spills, where oil is released into th ...
s. * Trajectory – The trajectory model, developed by
Environment Canada Environment and Climate Change Canada (ECCC; french: Environnement et Changement climatique Canada),Environment and Climate Change Canada is the applied title under the Federal Identity Program; the legal title is Department of the Environment ...
's
Canadian Meteorological Centre The Canadian Meteorological Centre (CMC; french: Centre météorologique canadien), located in Dorval, Quebec, is the branch of Environment Canada's Meteorological Service of Canada that is tasked with providing forecast guidance to national ...
(CMC), is a simple tool designed to calculate the
trajectory A trajectory or flight path is the path that an object with mass in motion follows through space as a function of time. In classical mechanics, a trajectory is defined by Hamiltonian mechanics via canonical coordinates; hence, a complete tr ...
of a few
air parcel In fluid dynamics, within the framework of continuum mechanics, a fluid parcel is a very small amount of fluid, identifiable throughout its dynamic history while moving with the fluid flow. As it moves, the mass of a fluid parcel remains constant, ...
s moving in the 3D wind field of the atmosphere. The model provides a quick estimate of the expected trajectory of an air parcel by the
advection In the field of physics, engineering, and earth sciences, advection is the transport of a substance or quantity by bulk motion of a fluid. The properties of that substance are carried with it. Generally the majority of the advected substance is al ...
transport mechanism, originating from (forward trajectory) or arriving at (backward trajectory) a specified geographical location and a vertical level.


Models developed in India

* HAMS-GPS – Software used for management of environment, health and safety (EHS). It can be used for training as well as research involving dispersion modeling, accident analysis, fires, explosions, risk assessments and other related subjects.


Air pollution dispersion models

*
ADMS 3 The ADMS 3 (Atmospheric Dispersion Modelling System) is an advanced atmospheric pollution dispersion model for calculating concentrations of atmospheric pollutants emitted both continuously from point, line, volume and area sources, or intermit ...
*
AERMOD The AERMOD atmospheric dispersion modeling system is an integrated system that includes three modules:Prater, E.T. and Midgley, C., ''A new air dispersion modeling system is helping create more accurate industrial source models'', Environmental Prot ...
*
CALPUFF __NOTOC__ 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. It is maintained by the model developers and distr ...
*
DISPERSION21 DISPERSION21 (also called DISPERSION 2.1) 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 model is widely ...
* PUFF-PLUME *
MERCURE Mercure may refer to: * MERCURE, an atmospheric dispersion modelling CFD code developed by Électricité de France * Mercure Hotels, a chain of hotels run by Accor * French ship Mercure (1783), French ship ''Mercure'' (1783) * Dassault Mercure, a ...
*
NAME A name is a term used for identification by an external observer. They can identify a class or category of things, or a single thing, either uniquely, or within a given context. The entity identified by a name is called its referent. A persona ...
* OSPM *
SAFE AIR SAFE AIR (Simulation of Air pollution From Emissions Above Inhomogeneous Regions) is an advanced atmospheric pollution dispersion model for calculating concentrations of atmospheric pollutants emitted both continuously or intermittently from p ...
* RIMPUFF
HAMS-GPS EIA modeling


Others

*
Air pollution dispersion terminology 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 ...
*
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 include algorithms to solve the mathematical equations that govern the pollutant ...
*
Bibliography of 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 include algorithms to solve the mathematical equations that govern the pollutant ...
*
Roadway air dispersion modeling 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, vehicl ...
*
Wind profile power law The wind profile power law is a relationship between the wind speeds at one height, and those at another. Definition The wind profile power law relationship is :\frac = \bigg(\frac \bigg)^\alpha where u is the wind speed (in metres per second) a ...


References

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


Further reading

For those who would like to learn more about atmospheric dispersion models, it is suggested that either one of the following books be read:
www.crcpress.com
*


External links

*{{curlie, Science/Environment/Air_Quality/Air_Dispersion_Modeling/, Air Dispersion Modeling

– From the website of Stuff in the Air
The Model Documentation System (MDS)
of the European Topic Centre on Air and Climate Change (part of the European Environment Agency) * USA EP
Preferred/Recommended ModelsAlternative ModelsScreening ModelsWiki on Atmospheric Dispersion Modelling
Addresses the international community of atmospheric dispersion modellers – primarily researchers, but also users of models. Its purpose is to pool experiences gained by dispersion modellers during their work.
The AUSPLUME modelThe CHARM modelFluidyn-PANACHE: 3D Computational Fluid Dynamcis(CFD) model for Dispersion AnalysisThe HAMS-GPS softwareThe RIMPUFF modelThe SPRAY modelValidation of the Urban Dispersion Model (UDM)
Atmospheric dispersion modeling