1. AERMAP Hands-on Course #423 Day 2 Afternoon
Air Pollution Dispersion Models:
Applications with the AERMOD Modeling System
AERMAP Hands-on
Course #423
Day 2 Afternoon

2. Day 2 Afternoon: AERMAP Hands-On

3. Learning Objectives At the end of this session, you will understand:
How to define a domain and download terrain data
The input required for AERMAP
Details of the control file
How to run AERMAP and review the output

4. Modeling Domain
The modeling domain is the geographic extent that contains all the receptors and sources being modeled plus a buffer to accommodate significant terrain elevations that could influence dispersion
May cross UTM zones
All coordinates must be referenced to same zone
The modeling domain as defined in AERMAP must encompass all receptors plus a buffer that includes any significant domain features that could influence dispersion at the defined receptors.
The modeling domain can cross UTM zones. All source and receptor locations must be referenced to the same UTM zone.

5. Modeling Domain How far should the modeling domain extend?
No specific guidance
Examine the region beyond the receptor network
Terrain similar to the terrain the receptors are located in may not require a much larger domain
More rugged or mountainous terrain beyond the receptors would likely require a larger domain to capture the most influential feature
Little guidance is provided for defining the modeling domain in AERMAP. If a large mountain is ‘near’ the receptor network, you would want to include that terrain feature; if it is far away, then it is probably best to omit that feature. You have two ways to omit terrain features: 1) in the initial download of the data, or 2) using the DOMAINXY or DOMAINLL keyword when you run AERMAP.
If you choose not to use DOMAINXY or DOMAINLL, by default, AERMAP will use the entire extent of the elevation data file(s) as the domain. This could significantly increase run time if the elevation file(s) cover a much larger geographic extent than the modeling domain. Omitting the domain definition may also mean that a large terrain feature in the distance is included that probably should not be included.
You should become familiar with terrain features within and near receptors when determining when and how to define the modeling domain in AERMAP.

6. Defining Receptor Locations
This slide displays the grid of discrete receptors we will use for our modeling scenario, represented in the file “MC_nested.dat.” The grid is centered on or close to / which is the approximate location of the Martins Creek source.
The grid shown includes receptors placed along the property/fenceline and a nested grid of discrete Cartesian receptors. The spacing of the receptors in the nested grid are 100-meters from the property line out to 2,000 meters (2 km) and 200-meter spacing out to 5,000 meters (5 km). A total of 3,817 receptors are used for this modeling scenario.
The receptor grid will be discussed in more detail later during this activity.

7. AERMAP – Obtaining Data
AERMAP processes one or more terrain files
A primary source of the data, without cost, is from the Multi-Resolution Land Characteristics (MRLC) Consortium website at
On the home page, click on ‘Find Data’ on the top row of links
Click on ‘MRLC Consortium Viewer’
With the ‘Data’ button, you can add map information such as roads and city names under ‘Layer Manager’ to assist in locating the area of interest
Center the map using the XY /USNG tool under Tools (use latitude and longitude
Zoom in to the area for which you need data
Zoom In under Controls menu, or
Use the vertical slider on the map , or
Us the mouse scroll wheel
As we have done with previous activities, we will download the terrain needed to run AERMAP for this hands-on activity. The terrain data will be from the National Elevation Dataset (NED) in GeoTIFF format. Like land cover data for AERSURFACE, NED data in GeoTIFF format can be can obtained free of charge from the MRLC Consortium website at the address shown.
We will review the steps needed to download data from the MRLC website. Should you run into difficulty, the AERSURFACE hands-on slides can be referenced for more specific help. Since the download site and procedures are the same, the level of detail presented in the AERSURFACE hands-on will not be repeated here.
In your web browser, type in click on Find Data and then click on MRLC Consortium Viewer. You should see a multi-colored map of the United States with the colors representing the land use characteristics.
First, be familiar with your site. If you do not have a good feel for the land use and terrain, zooming in to the site will be a challenge.
With the Layer Manager, you can switch on/off various types of information that may aid you in pin-pointing the area you want to download.

8. This slide is hidden to continue notes from previous slide.
To center the map on a particular geographic point, enter the LONGITUDE and LATITUDE (in that order) using ‘XY/USNG’ under the Tools menu. We can use the location of the Martins Creek source as a point of reference. The icon to click on to enter the longitude and latitude is an x-y axis (left of the question mark icon).
You can zoom into your site in a number of ways:
‘Zoom In’ under the Controls menu allows you to draw a box to zoom into (don’t forget to switch back to ‘Move Map’ if you want to move the map around and not accidentally zooming). This method requires knowing the approximate location of the site on a map of the U.S.
Use the vertical slider on the map
Use the scroll wheel on your mouse
A useful Tool is the measuring tool - the ‘Annotate/Measure’ tool. This tool allows you to determine about how far in each direction to define your domain. When you use this tool, you should first change the units displayed to meters or kilometers (the triangle icon on the icon bar of this tool). Click on the pencil icon to go back to allow you to measure distances and then on the zig-zag line icon.

9. AERMAP – Obtaining Data
To select the area to download data
Click on ‘Data’, then ‘Download Tool’
An action window opens that allow you to select the type of data to download
For AERMAP select 1 arc-second NED
Click on the icon in this action window that has the dashed red line around it to define the area ( )
Click and drag a rectangular box to encompass the region for which you need terrain data – go out 10,000 meters to the north, south, east, and west of the site
For the land use in the AERSURFACE hands-on, we went out about 5,000 meters in all directions. For the terrain data, we will go out around 10,000 meters in all directions to ensure a good buffer around the receptor grid and capture any significant terrain features close to the grid. (The receptor grid extends 5,000 meters in all directions from the source.)
The MRLC website offers 1 arc-second (~ 30-meter resolution) and 1/3 arc-second (~10-meter resolution) data files. AERMAP is capable of processing either resolution as well as others. It is possible the domain needed to encompass all receptors and sources will require multiple NED files. If more than one file is required to encompass the entire domain and the files are of multiple resolutions, AERMAP can process the multiple NED files that are not the same resolution. When file resolutions are mixed, higher resolution files should be listed first. If two or more files overlap geographically, AERMAP will assign the source/receptor to the file first encountered in which the source/receptor location is found.
Why would more than one file be necessary if you can define large geographic extents? If you choose to download something large, or example for the entire State of Pennsylvania, the server will automatically split each data product into multiple files. Note that currently there is a 1,500 Mb (1.5 Gb) limit on the file size(s), which is more than adequate for AERMAP applications.
This hands-on activity uses 1 arc-second data.
Don’t forget to click on the download tool prior to trying to draw the box to define the region of interest.

10. AERMAP – Obtaining Data
Completing the download
A new window opens (Request Summary page) showing what was selected
For elevation data, the default output format is ArcGRID – AERMAP cannot process this format
Change the format by clicking on ‘Modify Data Request’
When the new window opens, for the products you selected, click on the drop down for the archive format and choose GeoTIFF
At the top or bottom of the window, click on ‘Save Changes & Return to Summary’
Click the ‘Download’ button on the summary page – a new window opens with the status of the processing
Save the file to the location of your choice when the data extraction has completed
For elevation data, the default output is ArcGRID. It is important that you change the output format to GeoTIFF. Do this by clicking on “Modify Data Request” and specifying GeoTIFF as the format for the data type you are about to download. Be sure to save your changes. See the AERSURFACE hands-on presentation for detailed guidance.
Note: Some computers, corporate or personal, may block downloading files. You can download the file by clicking ‘here’ in the link embedded in the message: If an error occurs during download, click here to retrieve the download bundle.
Save the file to the location of your choice. We recommend putting it in “APTI 423\Hands-on\AERMAP\NED\.
Once the download is saved, go ahead and close the summary page.

11. Reviewing the Downloaded Data Files
Once the download is complete, review the data files
Unzip the file(s)
The following files are extracted from the zip file
METADATA.* - shapefile-related files (4 files)
NED auxiliary file (.aux)
NED projection data (.prj)
NED tif world file (.tfw)
NED GeoTIFF terrain data file (.tif) < -- file for AERMAP
NED Data Dictionary
Html and xml files with the metadata
Output parameters
Review these files, especially the projection and world files
The file that is downloaded contains several files in addition to the GeoTIFF file. Review them at your leisure.
World file: provides some information on the domain location and cell resolution, although the latter is in decimal degrees on the order of … degrees.
Projection data: contains information on the projection, datum, spheroid, units (decimal degrees), and vertical units.
The html files provide similar information and more. Nowhere, though, is the cell size represented in meters. However, if you realize that there is about 111 kilometers per degree of latitude, you can determine that is equivalent to meters, the resolution we want.
The GeoTIFF file which will be read by AERMAP contains the “.tif” file extension. You can leave the name as-is, though you might want to rename it to clearly indicate the type of data and the location it represents (i.e., MC_NED.tif).

12. AERMAP Hands-on Activity Files
A template for the AERMAP control file, receptor pathway file, and program executable (.exe) can be found in the following directory:
APTI423\Hands-on\AERMAP\
aermap.exe: program executable
MC_aermap.inp: AERMAP control file
MC_nested.dat: receptor pathway file
Do you remember where you unzipped your NED terrain data in GeoTIFF? (In the “NED” subdirectory?)
The files needed to complete the AERMAP hands-on activity should be found in the subfolder “APTI423\Hands-on\AERMAP\.”
There, you will find the AERMAP program executable (aermap.exe), the receptor pathway file (MC_nested.dat), and the AERMAP control file template (MC_aermap.inp). Notice the name of the control file. Any thoughts on what you might need to do first when you run AERMAP in a few minutes?
Do you remember where you downloaded or unzipped the NED terrain data? You will need to specify the path and filename when completing the AERMAP control file.

13. AERMAP – Control File Parameters
Data Type: National Elevation Data
Data File: Path and filename of the downloaded terrain data
Anchor Point: Easting, Northing, NADA value 4
Point Source Locations: MC ED HL
Receptors:
Include the file named MC_nested.dat
Output files:
Sources: MC_src.src
Receptors: MC_nested.rec
Shown here are the input parameters needed to complete the AERMAP control file for the Martins Creek site. A partially completed control file template, “MC_AERMAP.inp” which is displayed on the next slide has been provided. You will need a copy of this slide in front of you to fill in the missing parameters in the control file.
Note the following:
The anchor point in the user’s coordinate system is the same point as in the UTM coordinate system, i.e., you are working in the UTM coordinate system. Where the two sets of information might differ is if you are working in a local coordinate system (for example if your source or meteorological data were at (0,0)).
The DOMAINXY or DOMAINLL keyword can be used to limit the extent AERMAP checks in the NED file. This keyword is useful if the NED file is very large and the region of interest is much smaller. In this hands-on, we have “commented out” the keyword since the NED file is about 20 kilometers on a side.
The output filenames can be any name you like; we have shown the names that were used in developing the hands-on and are used in the AERMOD control file.

14. Filenames with spaces should be enclosed with double quotes
Control File
CO STARTING
TITLEONE
TITLETWO
DATATYPE
DATAFILE
ANCHORXY
RUNORNOT RUN
CO FINISHED
SO STARTING
LOCATION
SO FINISHED
RE STARTING
INCLUDED
RE FINISHED
OU STARTING
RECEPTOR
SOURCLOC
OU FINISHED
Filenames with spaces should be enclosed with double quotes
CO pathway
TITLEONE and TITLETWO can be any text to identify the AERMAP run.
DATATYPE: Options are DEM and NED - the file we downloaded is NED (National Elevation Data).
DATAFILE: The name of the tiff file AERMAP will use to obtain terrain elevations; here the file is one subfolder below the current folder.
ANCHORXY: Since the coordinates of the receptors are already in UTM coordinates, the user’s point (the first two values) is set equal to the anchor UTM coordinate. Any point in the domain will perform this function. The last value is the NADA value and is the horizontal datum used to establish the anchor point. Recall this value ranges from 0 to 6. The value 4 represents North American Datum of (NAD83). This information can be determined by examining the .prj file that accompanied the data download.
RUNORNOT: Run AERMAP, not just check the setup.

15. Defining Receptor Locations
Defining the receptor locations is discussed in the session on AERMOD setup as well
Gridded receptors are easier to specify since only parameters defining the starting point and node spacing is required
Without a GUI, discrete receptors are more difficult to specify, especially if there are thousands of receptors
A discussion of the various receptor networks was discussed in the preceeding AERMAP session and is included in the session on AERMOD set up
In our hands-on, we will be using discrete receptors
While AERMAP has multiple ways to specify receptor locations, there are advantages of each.
A gridded receptor network is simple to define. However, with a grid, it is impossible to remove receptors inside a facility boundary. This is an easier process with discrete receptors although locating them in the file might prove to be difficult.
Sometimes a program can be written or a spreadsheet program used to define the discrete receptors.

16. Defining Receptor Locations
This slide displays the grid of discrete receptors represented in the file “MC_nested.dat.”
The grid shown includes receptors placed along the property/fenceline and a nested grid of discrete Cartesian receptors. The spacing of the receptors in the nested grid are 100-meters from the property line out to 2,000 meters (2 km) and 200-meter spacing out to 5,000 meters (5 km). A total of 3,817 receptors are used for this modeling scenario.
Receptors are not included within the property boundaries. Be aware! Often an important distinction is made between the fenceline and property line. During this course and these activities, we are using the terms property line and fenceline interchangably with the assumption that public access to the property is restricted at the property boundary by a some barrier such as a fence (i.e., fenceline). It is not uncommon for the property boundary to extend beyond the fenceline and include areas where the property is accessible to the public (i.e., there is no barrier to prevent access). Typically, receptors will not be included in the area where public access is restricted, the fenceline, but may be included on the property beyond the fenceline where access is not prevented, even though accessing the property may be illegal (trespassing).
You should be aware of any modeling requirements related to the fenceline vs. property line specified by the regulatory agency, as well as ways of restricting public access other than fences (e.g., extreme slopes in complex terrain or along a beach).

17. Running AERMAP
AERMAP control file must be named “aermap.inp” (not case-sensitive)
To run AERMAP for this activity, open a command prompt and set the working directory to the folder where the control file is located
Copy or rename the control file to “aermap.inp”
At the command prompt, type: aermap
As with many of the programs, the control file is required to have a certain name. For AERMAP, the control file must be named “aermap.inp”. Do you remember which program we ran that did not have this requirement? (AERMINUTE)
If the control file you developed is not named “aermap.inp”, you can rename it to “aermap.inp”or copy it and rename the file (recommended so you have your original file saved). A sample command prompt is shown which copies the control file named “MC_aermap.inp” to “aermap.inp”. If your control file is named something more descriptive and you need to rename it or copy it to “aermap.inp,” it is often better to make a copy so you don’t later overwrite your control file with some other version by mistake.
To run AERMAP, type “aermap” at the command prompt.

18. Running AERMAP
As AERMAP runs, progress is displayed on screen for each source/receptor processed
The time required to process the data is dependent on
Number of receptors
Size of domain
Run time can range from minutes to several hours
Since AERMAP will check every node if a DOMAINXY (or XOMAINLL) is not included, AERMAP may run very slowly if the domain is significantly larger than the receptor network or source locations.
If AERMAP is running slowly, the processing can be stopped. Specifying a smaller domain may speed up the process.
Even if the domain size can be reduced, the number of receptors can slow down AERMAP. One option would be to break the receptors into groups and run AERMAP on two or more computers, then recombine the receptors for the AERMOD run.

19. AERMAP Output AERMAP produces several output files
AERMAP.OUT: general summary of the run
MAPDETAIL.OUT: summary of information regarding each DEM or NED file based on the results of the checking routines (for debugging problems)
MAPPARAMS.OUT: summary of the parameters for each DEM or NED file, based on the contents of the header record and documents the adjacency of the files within the application area (for debugging problems)
Source and receptor files with terrain elevations (and hill height scale for receptors)
AERMAP generates multiple files. A few of these are generated automatically, and the user cannot specify the file names, AERMAP.OUT, MAPDETAILS.OUT, and MAPPARAMS.OUT. These summarize the AERMAP run, contain detailed information about the data used (e.g., the corners of the NED file(s)), and can be used for debugging.
AERMAP also generates a separate source file and receptor file that contain the terrain elevations and hill height scales. These files are in the format required by AERMOD. Filenames are specified by the user in the control file. For our hands-on activity, the source and receptor files are “MC_nested.rec” and “MC_src.src”.

20. Source File Output MC_src.src
** AERMAP - VERSION /10/14
** :40:09
** APTI 423: AERMAP Hands-On
** Martins Creek NED Data File
** A total of NED files were used
** A total of sources were processed
** No user-specifed DOMAIN; all available data used
** ANCHORXY
** Terrain heights were extracted by default
SO ELEVUNIT METERS
SO LOCATION MC POINT
SO LOCATION ED POINT
SO LOCATION HL POINT
This slide shows the contents of the source output file (MC_src.src found in the folder Complete_Run) generated by AERMAP which reports the source elevations extracted from the terrain data file. This file is formatted such that it can be included (copied and pasted or use the INCLUDED keyword) directly in the source pathway (SO) of the AERMOD control file.
The first several records are header records that report summary information. The bottom part of the file contains the formatted source records including the source ID, source type, coordinates, and elevation.

21. Recptor File Output MC_nested.rec
** AERMAP - VERSION /10/14
** :40:09
** APTI 423: AERMAP Hands-On
** Martins Creek NED Data File
** A total of NED files were used
** A total of receptors were processed
** No user-specifed DOMAIN; all available data used
** ANCHORXY
** Terrain heights were extracted by default
RE ELEVUNIT METERS
DISCCART
DISCCART
DISCCART
DISCCART
DISCCART
DISCCART
DISCCART
DISCCART
DISCCART
DISCCART
DISCCART
DISCCART
DISCCART
DISCCART
DISCCART
DISCCART
This slide shows a portion of the receptor output file (MC_nested.rec) generated by AERMAP which reports the receptor elevations and hill height extracted from the terrain data file. This file is formated such that it can be included (copied and pasted or use the INCLUDED) keyword directly in the receptor pathway (RE) of the AERMOD control file.
The first several records are header records that report summary information. The bottom part of the file contains the formatted receptor records including the receptor type, coordinates, elevation, and hill height.