These refined dispersion models are listed in the Guideline on Air Quality Models - Appendix W (PDF) (54 pp, 761 K, 01-17-2017) and are required to be used for State Implementation Plan (SIP) revisions for existing sources and for New Source Review (NSR) and Prevention of Significant Deterioration (PSD) programs. 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.
CTDMPLUS - A refined point source gaussian air quality model for use in all stability conditions for 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.
The American Meteorological Society/Environmental Protection Agency Regulatory Model Improvement Committee (AERMIC) was formed to introduce state-of-the-art modeling concepts into the EPA's air quality models. Through AERMIC, a modeling system, AERMOD, was introduced that incorporated 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. As of December 9, 2006, AERMOD is fully promulgated as a replacement to ISC3, in accordance with Appendix W (PDF) (54 pp, 761 K, 01-17-2017) .
There are two input data processors that are regulatory components of the AERMOD modeling system: AERMET, a meteorological data preprocessor that incorporates air dispersion based on planetary boundary layer turbulence structure and scaling concepts, and AERMAP, a terrain data preprocessor that incorporates complex terrain using USGS Digital Elevation Data. Other non-regulatory components of this system include: AERSCREEN, a screening version of AERMOD; AERSURFACE, a surface characteristics preprocessor, and BPIPPRIM, a multi-building dimensions program incorporating the GEP technical procedures for PRIME applications.
At this time, AERMOD does not calculate design values for the lead NAAQS (rolling 3-month averages). A post-processing tool, LEADPOST (ZIP) (65 MB, 09-19-2013) , is available to calculate design values from monthly AERMOD output. This tool calculates and outputs the rolling cumulative (all sources) 3-month average concentration at each modeled receptor with source group contributions and the maximum cumulative (all sources) rolling 3-month average concentration by receptor.
Below is the model code and documentation for AERMOD Version 23132. The model code and supporting documents are not static but evolve to accommodate the best available science. Please check this website often for updates to model code and associated documents.
Read Me (TXT) (1 KB, 10-12-2023) - please read this file first
Sample Run Instructions (PDF) (33 pp, 1.7 MB, 10-12-2023) - detailed installation and execution instructions
Sample Run (ZIP) (5.4 MB, 10-12-2023) - sample test case
AERPLOT Sample Run Instructions (PDF) (15 pp, 627 KB, 10-12-2023) - detailed installation and execution instructions
AERPLOT Sample Run (ZIP) (4.3 MB, 10-12-2023) - sample test for AERPLOT
README (TXT) (2 KB, 01-22-2004) - Document that explains the databases below that contain input and output data for the model evaluation
AGA (ZIP) (2 MB, 01-22-2004) - Input/output data for AGA: Flat, Rural, Downwash, Independent
Alaska (ZIP) (661 KB, 01-22-2004) - Input/output data for Alaska: Flat, Rural Downwash, Developmental
Baldwin (ZIP) (4.5 MB, 01-22-2004) - Input/output data for Bladwin: Flat, Rural, Non-downwash, Independent
Bowline (ZIP) (2 MB, 01-22-2004) - Input/output data for Bowline: Flat, Rural, Downwash, Developmental/Independent
Clifty Creek (ZIP) (3.5 MB, 01-22-2004) - Input/output data for Clifty Creek: Flat, Rural , Non-downwash, Independent
DAEC (ZIP) (1 MB, 01-22-2004) - Input/output data for DAEC: Flat, Rural, Downwash, Developmental
EOCR (ZIP) (4 MB, 01-22-2004) - Input/output data for EOCR: Flat, Rural, Downwash, Independent
Indianapolis (ZIP) (1 MB, 01-22-2004) - Input/output data for Indianapolis: Flat, Urban, Non-downwash, Developmental
Kincaid SF6 (ZIP) (3 MB, 01-22-2004) - Input/output data for Kincaid SF6: Flat, Rural, Non-downwash, Developmental
Kincaid SO2 (ZIP) (5 MB, 01-22-2004) - Input/output data for Kincaid SO2: Flat, Rural, Non-downwash, Developmental
Lee Wind Tunnel (ZIP) (13 MB, 01-22-2004) - Input/output data for Lee Wind Tunnel: Flat, Rural, Downwash, Independent
Lovett (ZIP) (9 MB, 01-22-2004) - Input/output data for Lovett: Terrain, Rural, Non-downwash, Developmental
Martin's Creek (ZIP) (11.5 MB, 01-22-2004) - Input/output data for Martin's Creek: Terrain, Rural, Non-downwash, Independent
Millstone (ZIP) (660 KB, 01-22-2004) - Input/output data for Millstone: Flat, Rural, Downwash, Developmental
Prairie Grass (ZIP) (342 KB, 01-22-2004) - Input/output data for Prairie Grass: Flat, Rural, Non-downwash, Developmental
Tracy (ZIP) (2.5 MB, 01-22-2004) - Input/output data for Tracy: Terrain, Rural, Non-downwash, Independent
Westvaco (ZIP) (10 MB, 01-22-2004) - Input/output data for Westvaco: Terrain, Rural, Non-downwash, Independent
README (TXT) (1 KB, 10-31-2023) - Document that explains the NO2 databases below that contain input and output data for the model evaluation
Balko (ZIP)(12 MB, 10-31-2023) - Input/output data for Balko; Terrain, Rural, Downwash, Independent, 4 NO2 monitors
Denver-Julesburg (Supplemental for 2023 TSD) (ZIP) (2 MB, 10-31-2023) - Input/output data for Denver-Julesburg; Terrain, Rural, Downwash, Independent, 12 NO2 monitors
Denver-Julesburg (ZIP) (108 MB, 08-18-2020) - Input/output data for Denver-Julesburg: Flat, Rural, Non-downwash, Independent, 12 NO2 monitors
Empire Abo (ZIP)(14M, 10-31-2023) - Input/output data for Empire Abo; Flat, Rural, Downwash, Independent, 2 NO2 monitors
Pala'au (ZIP)(6 MB, 10-31-2023) - Input/output data for Pala'au; Flat, Rural, Downwash, Inpendent,1 NO2 monitor
Complex Terrain Dispersion Model Plus Algorithms for Unstable Situations (CTDMPLUS) is a refined point source gaussian air quality model for use in all stability conditions for complex terrain. The model contains, in its entirety, the technology of CTDM for stable and neutral conditions. CTSCREEN is the screening version of CTDMPLUS.
Code/Executable/Test Case (ZIP) (842 KB, 08-19-1993)Offshore and Coastal Dispersion Model Version 5 (OCD) is 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. OCD incorporates overwater plume transport and dispersion as well as changes that occur as the plume crosses the shoreline. Hourly meteorological data are needed from both offshore and onshore locations.
Code/Executable (ZIP) (9 MB, 01-06-2000)