Official websites use. Share sensitive information only on official, secure websites. JavaScript appears to be disabled on this computer. Please click here to see any active alerts. The models in this section include the following: AERMOD Modeling System - A steady-state plume model that incorporates air dispersion based on planetary boundary layer turbulence structure and scaling concepts, including treatment of both surface and elevated sources, and both simple and complex terrain.
OCD - A straight line Gaussian model developed to determine the impact of offshore emissions from point, area or line sources on the air quality of coastal regions. Executables ZIP 3. HGSYSTEM is a collection of computer programs designed to predict the source-term and subsequent dispersion of accidental chemical releases with an emphasis on denser-than-air dense gas behavior.
These models are used for prediction of transport and diffusion processes for complex terrain, coastal regions, urban areas, and around buildings where conventional models fail. Available from YSA Corporation. The traffic module is a microscale transportation model which simulates individual vehicle movement. The emission module uses speed distributions from the traffic module to determine composite emission factors; spatial and temporal distribution of emissions is based on the vehicle operation simulations.
The model tracks vehicle speed and acceleration distributions by signal phase per meter roadway segment for use in both emissions distribution and for induced flows and turbulence. The dispersion module uses a Lagrangian puff formulation, along with a gridded non-uniform wind and stability field derived from traffic module outputs, to describe near-roadway dispersion characteristics. HYROAD is designed to determine hourly concentrations of carbon monoxide CO or other gas-phase pollutants, particulate matter PM and air toxics - in consultation with appropriate Reviewing Authority - from vehicle emissions at receptor locations that occur within meters of the roadway intersections.
ISC3 is a steady-state Gaussian plume model which can be used to assess pollutant concentrations from a wide variety of sources associated with an industrial complex.
This model can account for the following: 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. For the status of ISC3 as a preferred model, please see the Note below. Complete copy is available from NTIS. 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. Available from fluidyn. A model used for estimating visual range reduction and atmospheric discoloration caused by plumes resulting from the emissions of particles, nitrogen oxides, and sulfur oxides from a single source.
The model predicts the transport, dispersion, chemical reactions, optical effects and surface deposition of point or area source emissions. In addition to the average concentration value, SCIPUFF provides a prediction of the statistical variance in the concentration field resulting from the random fluctuations in the wind field. Related Programs - Programs and utilities that are used in support of some of the dispersion models listed here.
Note that utilities designed for use with particular models will be found with those models. The EPA's Air Quality Modeling Group uses dispersion models as part of its modeling analyses for which information can be found at Modeling Applications and Tools and provides guidance on the use of these models for permit modeling available at Modeling Guidance and Support.
Additional information about dispersion models can be found at Air Modeling Resources. Skip to main content. Contact Us.
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