The AERMOD model (executable with Fortran source) supplied by the EPA on the SCRAM web site can be run on the Windows command line by supplying a specially structured and formatted input file and associated meteorological and other necessary prepared data files. For most users the preparation of the input file and data files has become very time intensive and prone to error. This has lead to a demand from casual as well as experienced model users for applications which help to prepare the files and run the model.
The rapidAER modeling system was developed as a Windows application to permit novice as well as experienced modelers to prepare the necessary inputs and launch the model with the least possible effort. rapidAER speeds up the task of input file preparation and slashes the running time for the model, especially for larger and more complex requirements.
rapidAER has greatly sped up the AERMOD modeling capabilities in three main areas:
rapidAER has a simplified interface, designed so that a new user with a simple modelling requirement is not forced to deal with screens that he does not need. Experienced modellers needing the full set of AERMOD capabilities can quickly access all functions and prepare the necessary inputs.
rapidAER uses the Google Earth application for graphical input of location data for sources, buildings, and receptors. Using the built-in graphic display as well as AERPLOT the user can easily prepare graphical files from outputs of the model.
rapidAER allows you to enter data once and reuse many times. With an integrated database, you can store common data for a facility including sources, buildings, boundary, grids, background concentrations, and emissions.
Copy an existing run from the database, import from csv and other files, or import an AERMOD input file to populate all of the fields in the run.
Access any information for the run or any other run in the database, in most cases with one mouse click.
Model run file management
A Modeling Dashboard provides a single screen for creating the input file, submitting and tracking model runs, reviewing model logs and model input/output files.
The system keeps track of all of the files created by the user to ensure compliance with the model requirements, which eliminates wasted time and reduces the possibility of submission errors.
The AERMET, AERMAP, AERPLOT, BPIP and related programs are integrated into the system, including automated data extraction and transfer to the source, building and grid components of the database.
rapidAER uses the Google Earth as interface to graphical input as well as display.
The Screen 3 program is incorporated and provides graphical output.
The AERMOD model performs a large number of calculations for each modeling hour for each source and receptor point. In a typical modeling run, the model performs the calculations for 5 years of meteorological data and builds the results tables in memory for output at the end of the run. For a large facility with 300 sources and 8000 receptors a run can take up to 5 days to execute on a fast PC. This must then be repeated for each chemical to be modeled and each operational scenario to be tested, which leads to extremely long computing times for a large facility project.
The runs for different chemicals or scenarios perform the same calculations except for the emission rates used to apply for the selected sources being modeled. rapidAER performs the calculation for unit emission rate and writes the resulting values for each hour for each source-receptor combination to a structured disk file. A separate post processor program then reads the source receptor data from disc with the emission rates appropriate for each source to reconstitute the hourly result grids and prepares the requested reports.
The creation of the base run can now take advantage of the multi CPU capability to split the meteorological period into a large number of smaller chunks and then combining the disk files to create a single file in a fraction of the 5 days it would take to run a large facility. The base file is then used to reconstitute a chemical run in a matter of seconds to several minutes.
The post-processor can then be run in multi-chemical mode where it can reconstitute 100 scenarios in the time it takes to run a single scenario. Coupled with the multi-CPU capability it would take about 20 hours to perform 300 chemical runs in addition to creation of the base run in about 10 hours, or several thousand runs in the time it takes to run a single AERMOD run on the command line.
Since all of the dispersion computations are made by the US EPA AERMOD code the rapidAER produces results exactly matching the EPA results.
The process of saving the hourly calculation results to a file also permits much more in-depth analysis and reporting, including complete source attribution.
It also facilitates the interactive modeling, where the user can perform scenarios without creating input files and obtain results within seconds.
For a more detailed discussion of the rapidAER capabilities and structure follow the link below to the rapidAER web site.