How Parallel Processing can Expedite Large AERMOD Model Runs

Due to advances in scientific knowledge, higher resolution raw data, stringent air quality standards, and changing regulations, environmental modeling is demanding more and more from EHS professionals and their computers.  All of these influences have resulted in significantly longer AERMOD model run times as compared to the predecessor regulatory model, ISCST.  Instead of minutes, AERMOD runtimes for large projects can take days and terrain data file sizes routinely exceed 100 MB.  To address the issue of increased runtimes, BREEZE Software offers a number of options to modelers to increase productivity while managing model complexity.

Parallel Processing on the Desktop

To assist with lengthy run times, BREEZE Software completed the complex process of developing parallel software for U.S. EPA's AERMOD regulatory dispersion model.  Utilizing the advancements in multi-core computing technology, BREEZE developed BREEZE AERMOD Parallel, which leverages the multi-core processers available in most modern computers and helps modelers dramatically reduce AERMOD model run times.

A two-core version, which can nearly double the speed of an AERMOD run, is included with every copy of BREEZE AERMOD.  BREEZE also offers four- and eight-core versions and can provide additional cores at a custom rate for use with more powerful machines.  With this approach, the user can purchase and determine how many processors are desired to run the AERMOD modeling scenario.

High Speed Cluster Computing

For very large AERMOD runs or for highly time-sensitive runs, the BREEZE Remote Modeling System (BRMS) provides the fastest possible results.  The BRMS can also be an essential resource when exploring acceptable scenarios for large-scale AERMOD projects.  The BRMS operates on a massively parallel computer cluster that harness the processing power of multiple multi-core computers.  Multi-core computers have more than one processing unit, or CPU, on a computer chip.  Each core can be viewed as a separate computer capable of performing independent calculations.  By utilizing the BRMS to process the numerically intensive algorithms and data often associated with AERMOD, modelers save time and money.

EQSummer2016 BREEZE Article Figure 1 Program Menu  

The BRMS is a Web-enabled application that requires no proprietary software interface, allowing modelers to submit data online anytime (24/7).  Users may also submit runs directly through their BREEZE AERMOD interface if preferred.  Before submitting a modeling scenario, a user must request a BRMS key.  This key protects the confidentiality of all users by allowing a user to view only submissions associated with their key.  After receiving the key, users can simply upload input files anytime through our online webpage or directly through their BREEZE AERMOD interface.  Email notifications inform users of the model run status and a link to the completed results.  Costs and time estimates for each run are based on a number of variables including, but not limited to, the following:  number of sources and receptors, type of sources, and output selected.

EQSummer2016 BREEZE Article Figure 2 Job Submittal Form  

BREEZE offers a number of other options to assist modelers dealing with large AERMOD projects.  Modelers have the ability to schedule mul­tiple model runs sequentially in BREEZE AERMOD, enabling the user to perform runs overnight or while they are away from their computer.  Another convenient feature is the Restart option, which is useful in case of a power failure or user interrupt.  With the Restart option, intermediate results are saved and the model run can be restarted at the last place it was saved.

To learn more about high speed modeling options, contact the BREEZE Team at or +1 (972) 661-8881.