When using the US EPA AERMOD model, it is often necessary to give the same properties to several sources. For example, for a facility that has seasonal operations, the same variable emission rate may apply to many sources. Rather than entering the same information repeatedly, it is possible to use source ranges to specify a series of sources to which the same information will be applied.
Using Source Ranges
A source range is identified in the AERMOD input file by two source IDs separated by a dash (for example STACK1-STACK10). While source ranges are easily specified, it is crucial that the sources are named in a manner conducive to the source range, that is, the sources must be identifiable to AERMOD as belonging between the two source IDs specified in the source range.
When reading a source range, AERMOD separates each of the source IDs into three parts:
1) an alphabetical part,
2) a numerical part, and
3) the remainder
Each of these three parts must fall within their respective ranges. Several examples are shown in the table below, note that each component of the source ID has been color coded:
Using Source Ranges
A source range is identified in the AERMOD input file by two source IDs separated by a dash (for example STACK1-STACK10). While source ranges are easily specified, it is crucial that the sources are named in a manner conducive to the source range, that is, the sources must be identifiable to AERMOD as belonging between the two source IDs specified in the source range.
When reading a source range, AERMOD separates each of the source IDs into three parts:
1) an alphabetical part,
2) a numerical part, and
3) the remainder
Each of these three parts must fall within their respective ranges. Several examples are shown in the table below, note that each component of the source ID has been color coded:
| Source Range | Examples of Source in the Range | Examples of Sources not in the Range |
|---|---|---|
| STACK1-STACK10 | STACK4, STACK9 | STACK2a, STACK11, St5 |
| VENT1A-VENT3C | VENT1B, VENT2A | VENT2, VENT3D |
| 5SRC-9SRC | 8SRC, 6SRC | NEW6SRC |
These examples are relatively simple, but it is possible to create much more confusing source names. It is a good practice to keep source names as simple as possible if you intend to use a source range.
Verifying Results
Whenever you use a source range, it is advisable to confirm that the model interpreted the range as you anticipated. This can be done by checking the summary of model inputs, which can be found in the AERMOD output file.
Example
In this simple example, we have three stacks, STCK1, STCK2 and STCK3. The emissions of all three stacks vary seasonally in the same manner, so the variable emissions will be entered using a source range. In the AERMOD input file, the following would be written:
To verify if the model will consider the source range the way you expected, you should run AERMOD in the “Verify Run” mode (CO RUNORNOT NOT). In this mode, AERMOD will simply read and analyze the input file and report any errors or warning messages that are generated. All of the inputs are then summarized in the output file for the user to review.
Once the model has been run, the source range can be verified by looking in the summary of model inputs, in the output file:
Verifying Results
Whenever you use a source range, it is advisable to confirm that the model interpreted the range as you anticipated. This can be done by checking the summary of model inputs, which can be found in the AERMOD output file.
Example
In this simple example, we have three stacks, STCK1, STCK2 and STCK3. The emissions of all three stacks vary seasonally in the same manner, so the variable emissions will be entered using a source range. In the AERMOD input file, the following would be written:
EMISFACT STCK1-STCK3 SEASON 0.1 0.5 0 1
To verify if the model will consider the source range the way you expected, you should run AERMOD in the “Verify Run” mode (CO RUNORNOT NOT). In this mode, AERMOD will simply read and analyze the input file and report any errors or warning messages that are generated. All of the inputs are then summarized in the output file for the user to review.
Once the model has been run, the source range can be verified by looking in the summary of model inputs, in the output file:
* SOURCE EMISSION RATE SCALARS WHICH VARY SEASONALLY *
WINTER SPRING SUMMER FALL
- - - - - - - - - - - - - - - - - - - - - - - - - - - - -
SOURCE ID = STCK1 ; SOURCE TYPE = POINT :
.10000E+00 .50000E+00 .00000E+00 .10000E+01
SOURCE ID = STCK2 ; SOURCE TYPE = POINT :
.10000E+00 .50000E+00 .00000E+00 .10000E+01
SOURCE ID = STCK3 ; SOURCE TYPE = POINT :
.10000E+00 .50000E+00 .00000E+00 .10000E+01
The summary clearly shows that all three sources were included in the source range, and had the appropriate emission factors applied.
Once your input file was successfully verified, then you can run the model, this time in “Calculation” mode (CO RUNORNOT RUN).
Once your input file was successfully verified, then you can run the model, this time in “Calculation” mode (CO RUNORNOT RUN).
Recent Posts
