Although the advanced physics in U.S. EPA's AERMOD more accurately represent dispersion of pollutants in the atmosphere, it comes with the disadvantage of greatly increased model run times. Even for a comparatively small project containing a few thousand receptors and a dozen sources, the runtimes can last longer than an hour. This makes the scenario where dozens of runs need to submitted for the purpose of model refinements (e.g., testing the impact of a stack height change very cumbersome. On the other hand, large projects comprising of hundreds of sources can expect run times to take several days.
Last month's modeling tip discussed how modelers can minimize modeling runtimes at a minimal cost using BREEZE's parallel processing services. In this modeling tip, we will discuss the Schedule Batch Run and Restart options available in BREEZE AERMOD that improve efficiency for batch runs and save modelers time in the event of a power failure or user interruption.
Schedule Batch Run Option
BREEZE AERMOD provides modelers with an option to schedule more than one modeling scenario sequentially. Once the model setup is ready, users can schedule batch runs by following these steps in BREEZE AERMOD:
- Navigate to the Project Tab and select the Schedule Runs option in the Other dropdown menu.
- In the Schedule Model Runs form:
- Click the Add button and selecting the model runs you want to schedule
- Under the Schedule time section, you can choose between the following options:
- Now: Begins running the sequence of model runs after the Start button is selected.
- User defined: Specify a time in the future to begin the sequence of model runs after the Start button is selected.
Note: The computer must be powered on to run the model at the specified time.
- In the Select model runs section, additional information about the batch runs is available:
- The Up and Down buttons may be used to select and arrange the sequence of model runs. The Remove button may be used to remove the selected model run from the batch.
- By default, the FORTRAN executable selected in the model input file is displayed. However, the user has the option to select an alternative executable if needed.
- Users also have the option to select the number of processors to use for the individual runs. Note: This option is only available if the BREEZE AERMOD Parallel hardware key in plugged in to your computer and is only valid for executables that have the MPI designator in its name.
- Once you have scheduled the runs and selected the applicable executable and processors, click the Start button to begin the batch runs. The model runs are color coded to represent the status of the scheduled runs.
- Green: Model scenario completed successfully
- Red: Model scenario did not complete successfully
- Grey: Model scenario currently running
- White: Model scenario has not yet begun
- In the Display section, you may select the following options to view more information about the batch runs:
- Model Run displays the status of the project run currently running
- Run log displays a status summary of all the runs scheduled
- Model Output does not display after the run is completed. Users can open the model results by opening the .ami file in BREEZE AERMOD and the .amz file in BREEZE 3D Analyst to view the model results once the scheduled batch runs are completed.
BREEZE AERMOD also offers an option for users to save intermediate results in an unformatted file so that if there is a power failure or user interruption, the model run can be restarted using this file at the last place it was saved. To save the intermediate results, users will need to complete the steps:
- Navigate to the Project Tab and select Output in the Model Options section.
- Once in the Output Options form, select Save file. This will duplicate your .ami file and use the .ams extension.
- The .ams file is needed to restart the model runs from the last program save. To find the file, complete the following steps:
- Open the Control Options menu in the Project Tab
- Go to the Other Options Tab
- Find the file by clicking the “…” button in the Restart file field and select the last saved .ams extension file. Click OK and you are ready to restart your project run.
Utilizing the Schedule Batch Runs and the Restart option saves modelers time and effort. If you have questions about when to use these options or how to find the .ams file, click Help to access the user guide or contact the BREEZE Support Team at firstname.lastname@example.org or +1 (972) 661-8881.