Now that we've completed all preprocessors, we can finally work on the main processor responsible for generating pollutant concentration outputs for our study area.
AERMOD (American Meteorological Society/Environmental Protection Agency Regulatory Model) is an atmospheric dispersion model developed by the U.S. EPA in partnership with AMS, designed to assess air quality and estimate atmospheric pollutant concentrations from industrial sources. It's widely used for environmental licensing studies and air emission impact assessments.
The model simulates pollutant transport, dispersion, and deposition, considering terrain influences, local meteorology, and emission source characteristics. AERMOD is particularly recommended for local and regional scale modeling (up to 50 km from the source).
AERMOD's primary purpose is to estimate hourly, daily, monthly, and annual average pollutant concentrations in ambient air, based on source characteristics, meteorological conditions, and local topography.
| Component | Description |
|---|---|
| Meteorological data | Processed via AERMET; includes wind speed/direction, temperature, etc. |
| Topographic data | Processed via AERMAP; terrain elevation for sources and receptors |
| Emission sources | Coordinates, type (point, area, volume), emission rate and height |
| Receptors | Geographic locations where concentrations will be calculated |
| Control options | Modeling parameters, simulation period, output options, etc. |
| Output | Description |
|---|---|
| Concentrations | Maximum and average concentration values for different periods (1h, 24h, annual) |
| Receptor coordinates | Locations of points with calculated concentration values |
| Maps and graphs | Can be generated with auxiliary software (e.g., GIS/AERPLOT) based on results |
As usual, we first need to download the AERMOD executable from the EPA AERMOD website, extracting the file to the folder C:\Users\Cliente\Desktop\AermodTutorial\5.AERMOD.
The emission sources file is unfortunately not publicly available, so I'm providing the download here. Don't forget to extract this file to C:\Users\Cliente\Desktop\AermodTutorial\5.AERMOD.
First, we'll create two new folders within AERMOD:
AERMET - Containing METAR.pfl and METAR.sfc data
AERMAP - Bloomington.rec and Bloomington.src
Now that files are properly stored, we'll begin creating AERMOD.
For this, create a text document called AERMOD, and configure it as follows:
CO STARTING TITLEONE Bloomington-IL TITLETWO Emission SO2 MODELOPT DFAULT CONC AVERTIME 1 8 24 POLLUTID SO2 RUNORNOT RUN ERRORFIL msg.err CO FINISHED SO STARTING ** X Y Z ** ------ ------ ------ SO LOCATION STACK1 POINT 333415 4482405 256.09 ** Point Source QS HS TS VS DS ** Parameters: ----- ---- ---- ---- --- SRCPARAM STACK1 0.0 182.9 0.0 0.0 5.3 HOUREMIS .\Emissions\Emission.emi STACK1 ** Building Data SO BUILDHGT STACK1 100.00 100.00 60.00 0.00 0.00 0.00 SO BUILDHGT STACK1 60.00 60.00 60.00 60.00 60.00 60.00 SO BUILDHGT STACK1 60.00 100.00 100.00 100.00 100.00 100.00 SO BUILDHGT STACK1 100.00 100.00 60.00 0.00 0.00 0.00 SO BUILDHGT STACK1 60.00 60.00 60.00 60.00 60.00 60.00 SO BUILDHGT STACK1 60.00 100.00 100.00 100.00 100.00 100.00 SO BUILDWID STACK1 96.41 90.33 140.52 0.00 0.00 0.00 SO BUILDWID STACK1 151.52 172.22 187.68 197.44 201.21 198.85 SO BUILDWID STACK1 190.46 82.32 90.93 96.77 99.68 99.55 SO BUILDWID STACK1 96.41 90.33 140.52 0.00 0.00 0.00 SO BUILDWID STACK1 151.52 172.22 187.68 197.44 201.21 198.85 SO BUILDWID STACK1 190.46 82.32 90.93 96.77 99.68 99.55 SO BUILDLEN STACK1 99.99 98.73 198.85 0.00 0.00 0.00 SO BUILDLEN STACK1 200.68 200.25 193.73 181.32 163.40 140.52 SO BUILDLEN STACK1 113.37 63.13 75.64 85.85 93.45 98.21 SO BUILDLEN STACK1 99.99 98.73 198.85 0.00 0.00 0.00 SO BUILDLEN STACK1 200.68 200.25 193.73 181.32 163.40 140.52 SO BUILDLEN STACK1 113.37 63.13 75.64 85.85 93.45 98.21 SO XBADJ STACK1 77.35 68.80 -46.23 0.00 0.00 0.00 SO XBADJ STACK1 -113.41 -130.06 -142.77 -151.14 -154.91 -153.98 SO XBADJ STACK1 -148.37 -145.41 -162.21 -174.09 -180.67 -181.77 SO XBADJ STACK1 -177.34 -167.53 -152.62 0.00 0.00 0.00 SO XBADJ STACK1 -87.28 -70.18 -50.96 -30.18 -8.49 13.46 SO XBADJ STACK1 35.00 82.27 86.57 88.24 87.22 83.56 SO YBADJ STACK1 41.75 63.23 83.72 0.00 0.00 0.00 SO YBADJ STACK1 98.33 94.56 87.93 78.62 66.93 53.20 SO YBADJ STACK1 37.85 70.72 49.88 27.52 4.32 -19.00 SO YBADJ STACK1 -41.75 -63.23 -83.72 0.00 0.00 0.00 SO YBADJ STACK1 -98.33 -94.56 -87.93 -78.62 -66.93 -53.20 SO YBADJ STACK1 -37.85 -70.72 -49.88 -27.52 -4.32 19.00 SRCGROUP ALL SO FINISHED RE STARTING INCLUDED .\AERMAP\Bloomington.REC RE FINISHED ME STARTING SURFFILE .\AERMET\METAR.sfc free PROFFILE .\AERMET\METAR.pfl free SURFDATA 14842 2024 Bloo SITEDATA 00001 2024 Bloo UAIRDATA 72532 2024 Bloo PROFBASE 821 STARTEND 2024 5 1 2024 5 3 ME FINISHED OU STARTING RECTABLE allave first fourth MAXTABLE allave 400 PLOTFILE 1 all 4 Bloomigton.plt SUMMFILE Bloomington.sum OU FINISHED
This block defines the control options for the simulation.
| Line | Description |
|---|---|
| CO STARTING | Start of the control options block. |
| TITLEONE Bloomington-IL | Simulation title line 1, used in output files. |
| TITLETWO Emission SO2 | Simulation title line 2, complements the case description. |
| MODELOPT DFAULT CONC | Uses default model options (DFAULT) and performs concentration calculations (CONC). |
| AVERTIME 1 8 24 | Averaging periods: 1 hour, 8 hours, and 24 hours. |
| POLLUTID SO2 | Pollutant being modeled: sulfur dioxide (SO₂). |
| RUNORNOT RUN | Indicates that the simulation should be executed. |
| ERRORFIL msg.err | File where error messages will be logged. |
| CO FINISHED | End of the control options block. |
Defines the emission source(s), their physical characteristics, and associated buildings.
Source Location
| Line | Description |
|---|---|
| SO STARTING | Start of the source definition block. |
| SO LOCATION STACK1 POINT 333415 4482405 256.09 | Source STACK1 of type POINT, located at UTM coordinates (X=333415, Y=4482405), with base elevation of 256.09 m. |
Source Parameters
| Line | Description |
|---|---|
| SRCPARAM STACK1 0.0 182.9 0.0 0.0 5.3 | Stack parameters: emission rate (0.0), stack height (182.9 m), gas temperature (0.0), exit velocity (0.0), stack diameter (5.3 m). |
| HOUREMIS .\Emissions\Emission.emi STACK1 | File with hourly emission rates for source STACK1. |
Building Geometry (Downwash) The following lines provide data for downwash calculations due to nearby structures.
| Type | Source | Values (repeated lines) |
|---|---|---|
| SO BUILDHGT | STACK1 | Building heights (in meters), for multiple directions. |
| SO BUILDWID | STACK1 | Building widths (in meters), for multiple directions. |
| SO BUILDLEN | STACK1 | Building lengths (in meters), for multiple directions. |
| SO XBADJ | STACK1 | X-coordinate offsets (building position relative to the source). |
| SO YBADJ | STACK1 | Y-coordinate offsets. |
Note: These values are used for downwash calculations via PRIME. We used generic data from other models to define this geometry.
Source Grouping
| Line | Description |
|---|---|
| SRCGROUP ALL | Groups all sources under the group ALL, used for output processing. |
| SO FINISHED | End of the source definition block. |
| Line | Description |
|---|---|
| RE STARTING | Start of the receptor definition block. |
| INCLUDED .\AERMAP\Bloomington.REC | Receptor file generated by AERMAP. |
| RE FINISHED | End of the receptor block. |
4. Meteorological Data Block (ME) Defines the meteorological input files processed by AERMET.
| Line | Description |
|---|---|
| ME STARTING | Start of the meteorological data block. |
| SURFFILE .\AERMET\METAR.sfc free | Surface data file (.sfc). |
| PROFFILE .\AERMET\METAR.pfl free | Upper air profile file (.pfl). |
| SURFDATA 14842 2024 Bloo | Surface station code: 14842, year 2024, location “Bloo”. |
| SITEDATA 00001 2024 Bloo | Modeled site identifier: 00001. |
| UAIRDATA 72532 2024 Bloo | Upper air station code: 72532. |
| PROFBASE 821 | Base height for profiles (in meters), used for interpolation. |
| STARTEND 2024 5 1 2024 5 3 | Simulation period: May 1 to May 3, 2024. |
| ME FINISHED | End of the meteorological data block. |
Defines the output options for the simulation.
| Line | Description |
|---|---|
| OU STARTING | Start of the output definitions block. |
| RECTABLE allave first fourth | Table of average concentrations per receptor (allave), including the first and fourth highest values. |
| MAXTABLE allave 400 | Table of maximum values per receptor for allave, up to 400 values. |
| PLOTFILE 1 all 4 Bloomington.plt | Plot file for group all, format 1, averaging period 4. |
| SUMMFILE Bloomington.sum | Summary file containing simulation statistics. |
| OU FINISHED | End of the output block. |
Now that everything is ready, we can run our processor. To do this, open the Command Prompt (CMD) and type cd C:\Users\Cliente\Desktop\AermodTutorial\5.AERMOD, press enter, then type aermod aermod.txt, press enter again and…
Done! Your file now contains all the meteorological data for the region you selected, and we will mainly use the PLOTFILE 1 all 4 Bloomigton.plt, which will be used to create contour maps (isoconcentration) and other spatial representations.
Now everything directly related to AERMOD is finished, with only the processor AERPLOT remaining, a tool used solely for visualization, which we will cover in the next section…
Here you can download the folder I used to create this document. It is important that you use it only for comparison purposes or in case you are unable to make progress on the project. Attached: aermod.rar