5. AERMOD

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.

5.1. Introduction

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).

Objective

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.

Input Data

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 Data

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

5.2. Required Files for AERMOD

5.2.1 Downloading AERMOD Executable

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.

5.2.2 Downloading Emission Sources

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.

5.3. Configuring 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

Control Options Block (CO)

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.

Source Data Block (SO)

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.

Receptor Data Block (RE)

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.

Output Data Block (OU)

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.

5.3. Running the AERMOD

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…

5.4. What is Next?

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…

Attachment

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

TraPoDisO

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