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Support Center for Regulatory Atmospheric Modeling (SCRAM)

Air Quality Dispersion Modeling - Preferred and Recommended Models

These refined dispersion models are listed in Appendix W (PDF)(45 pp, 803 K, About PDF) 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.

CALINE3 - A steady-state Gaussian dispersion model designed to determine air pollution concentrations at receptor locations downwind of highways located in relatively uncomplicated terrain.

CAL3QHC/CAL3QHCR - CALINE3 based CO model with queuing and hot spot calculations and with a traffic model to calculate delays and queues that occur at signalized intersections.

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.


AERMOD Modeling System

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.

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 M), 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 18081. 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. As of December 9, 2006, AERMOD is fully promulgated as a replacement to ISC3, in accordance with Appendix W (PDF).

AERMOD Modeling System Code and Documentation
AERMOD Implementation Guide
AERMOD Implementation Guide (PDF)(39 pp, 182 K, 2018) - Provides information on the recommended use of AERMOD for particular applications and is an evolving document.
Model Code
Executable (v18081) (ZIP)(1.4 M, 2018) - 64-bit Operating Systems
Executable (v18081) (ZIP)(1.2 M, 2018) - 32-bit Operating Systems
Source Code (v18081) (ZIP)(518 K, 2018)
Model Documentation

AERMOD Quick Reference Guide (PDF) (6 pp, 85 K, 2018)
User's Guide (PDF)(302 pp, 1.7 M, 2018)

Model Change Bulletin #13 - Version Date 18081 (PDF) (4 pp, 127 K, 2018)
Model Change Bulletin #12 - Version Date 16216 (PDF) (2 pp, 167 K, 2016)
Model Change Bulletin #11 - Version Date 15181 (PDF) (3 pp, 43 K, 2015)
Model Change Bulletin #10 - Version Date 14134 (PDF) (6 pp, 37 K, 2014)
Model Change Bulletin #9 - Version Date 13350 (TXT)(9 K, 2013)
Model Change Bulletin #8 - Version Date 12345 (TXT)(9 K, 2012)
Model Change Bulletin #7 - Version Date 12060 (TXT)(6 K, 2012)
Model Change Bulletin #6 - Version Date 11353 (TXT)(3 K, 2011)
Model Change Bulletin #5 - Version Date 11103 (TXT)(3 K, 2011)
Model Change Bulletin #4 - Version Date 11059 (TXT)(13 K, 2011)
Model Change Bulletin #3 - Version Date 09292 TXT)(3 K, 2009)
Model Change Bulletin #2 - Version Date 07026 (TXT)(4 K, 2007)
Model Change Bulletin #1 - Version Date 06341 (TXT)(10 K, 2006)

Model Formulation and Evaluation Document (PDF)(183 pp, 3.6 M, 2018)

Test Cases
AERMET-AERMOD Test Comparisons (XLSX)(858 K, 2018)
AERMOD Test Cases (ZIP)(400.5 M, 2018)
 
Installation Guide (Sample Run)

Read Me (TXT)(1 K, 2014) - please read this file first
Sample Run Instructions (PDF)(13 pp, 749 K) - detailed installation and execution instructions
Sample Run (ZIP)(1 M) - sample test case

AERPLOT Sample Run Instructions (PDF)(5 pp, 589 K) - detailed installation and execution instructions
AERPLOT Sample Run (ZIP)(4.3 M) - sample test for AERPLOT

Model Supporting Documents

Model Evaluation Paper (PDF) (41 pp, 1 M, 2005)
Bulk Richardson Number Evaluation Report (PDF)(34 pp, 329 K, 2004)
Comparison of Regulatory Design Concentrations: AERMOD vs ISCST3, CTDMPLUS, ISC-PRIME (PDF)(89 pp, 31 K, 2003)
Development and Evaluation of the PRIME Plume Rise and Building Downwash Model (PDF)(5 pp, 31 K, 1998)
Project PRIME: Evaluation of Building Downwash Models Using Field and Wind Tunnel Data (PDF)(44 pp, 18 K, 1998)
Development and Evaluation of the PRIME Plume Rise and Building Downwash Model (PDF)(34 pp, 588 K, 1999)
Evaluation of Bias in AERMOD-PVMRM (PDF)(33 pp, 236 K, 2005)
PVMRM and OLM Sensitivity Analysis (PDF)(67 pp, 522 K, 2004)
Ambient Ratio Method Version 2 (ARM2) Development and Evaluation Report (PDF)(67 pp, 2 M, 2004)
AERMOD Deposition Science Document (PDF)(95 pp, 196 K, 2013)
AERMOD Deposition Parameterizations Document (ZIP)(338 K)
Draft Peer Review Document (ZIP)(797 K) - For the AERMOD Deposition Parameterizations Document (above)
Technical Support Document (TSD) for AERMOD/BLP Development and Testing (43 pp, 1.0 M, 2016)
Technical support document (TSD) for NO2-related AERMOD modifications (32 pp, 1.6 M, 2016)

Model Evaluation Databases
README (TXT)(1 K) - Document that explains the databases below that contain input and output data for the model evaluation
AGA (ZIP)(2 M) - Input/output data for AGA: Flat, Rural, Downwash, Independent
Alaska (ZIP)(661 K) - Input/output data for Alaska: Flat, Rural Downwash, Developmental
Baldwin (ZIP)(4.5 M) - Input/output data for Bladwin: Flat, Rural, Non-downwash, Independent
Bowline (ZIP)(2 M) - Input/output data for Bowline: Flat, Rural, Downwash, Developmental/Independent
Clifty Creek (ZIP)(3.5 M) - Input/output data for Clifty Creek: Flat, Rural , Non-downwash, Independent
DAEC (ZIP)(1 M) - Input/output data for DAEC: Flat, Rural, Downwash, Developmental
EOCR (ZIP)(4 M) - Input/output data for EOCR: Flat, Rural, Downwash, Independent
Indianapolis (ZIP)(1 M) - Input/output data for Indianapolis: Flat, Urban, Non-downwash, Developmental
Kincaid SF6 (ZIP)(3 M) - Input/output data for Kincaid SF6: Flat, Rural, Non-downwash, Developmental
Kincaid SO2 (ZIP)(5 M) - Input/output data for Kincaid SO2: Flat, Rural, Non-downwash, Developmental
Lee Wind Tunnel (ZIP)(13 M) - Input/output data for Lee Wind Tunnel: Flat, Rural, Downwash, Independent
Lovett (ZIP(9 M) - Input/output data for Lovett: Terrain, Rural, Non-downwash, Developmental
Martin's Creek (ZIP)(11.5 M) - Input/output data for Martin's Creek: Terrain, Rural, Non-downwash, Independent
Millstone (ZIP)(660 K) - Input/output data for Millstone: Flat, Rural, Downwash, Developmental
Prairie Grass (ZIP)(342 K) - Input/output data for Prairie Grass: Flat, Rural, Non-downwash, Developmental
Tracy (ZIP)(2.5 M) - Input/output data for Tracy: Terrain, Rural, Non-downwash, Independent
Westvaco (ZIP)(10 M) - Input/output data for Westvaco: Terrain, Rural, Non-downwash, Independent

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CALINE3

CALINE3 is a steady-state Gaussian dispersion model designed to determine air pollution concentrations at receptor locations downwind of highways located in relatively uncomplicated terrain. CALINE3 is incorporated into the more refined CAL3QHC and CAL3QHCR models.

CALINE3 Model Code and Documentation
Model Code
Code/Executable/Test Case (ZIP)(442 K)
Model Documentation
User's Guide - Unabridged (PDF)(184 pp, 7.6 M, 1979)
User's Guide - Abridged (PDF)(34 pp, 108 K, 1979)
Latest Model Change Bulletin (TXT)(6 K, 1989)

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CAL3QHC/CAL3QHCR

CAL3QHC is a CALINE3 based CO model with queuing and hot spot calculations and with 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. Both models are available below.

CAL3QHC/CAL3QHCR Model Code and Documentation
Model Code
CAL3QHC Executable (ZIP)(235 K)
CAL3QHCR Executable (ZIP)(917 K)
Model Documentation
CAL3QHC User's Guide (PDF) (98 pp, 2.4 M, 1995)
Latest CAL3QHC Model Change Bulletin (TXT)(5 K, 2004)

CAL3QHCR User's Guide (PDF)(96 pp, 209 K, 1995)
Latest CAL3QHCR Model Change Bulletin (TXT)(3 K, 2013)

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CTDMPLUS

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.

CTDMPLUS Model Code and Documentation
Model Code
Model Documentation
User's Guide Supplement (PDF)(5 pp, 60 K, 1993)
User's Guide, Volume 1 (PDF)(210 pp, 7 M, 1989)
User's Guide, Volume 2 (PDF)(77 pp, 2 M, 1990)
User's Guide for Terrain Preprocessor (PDF)(180 pp, 6 M, 1988)
User's Guide for Meteorological Preprocessor (PDF)(166 pp, 5 M, 1989)
Final Report (PDF)(484 pp, 16 M, 1987)
Latest Model Change Bulletin (TXT)(5 K, 1993)

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OCD

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.

OCD Model Code and Documentation
Model Code
Model Documentation
User's Guide (ZIP)(369 M)
User's Guide Supplement (PDF)(204 pp, 3 M, 1989)
Latest Model Change Bulletin (TXT)(6 K, 2000)

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