May 13, 2020

Due to advances in scientific knowledge, higher resolution raw data, stringent air quality standards, and ever-changing regulations, environmental modeling is demanding more and more from EHS professionals and their computers, resulting in significantly longer AERMOD model runtimes. To combat these increased runtimes, BREEZE's parallel processing capabilities can be used to expedite the processing through the use of a multi-CPU environment. This high-performance application produces pollutant concentration estimates, identical to EPA's AERMOD Fortran executable. The only code change to the application is the addition to implement the parallel processing feature, so the application runs the exact algorithms while on multiple processors, saving modelers time and money.

BREEZE AERMOD Parallel 2-CPU, which can nearly double the speed of an AERMOD run, is included with every purchase of BREEZE AERMOD. (Those interested in utilizing additional cores to process AERMOD runs even faster can purchase BREEZE AERMOD 4-CPU, 8-CPU, 16-CPU, or 32-CPU in addition to the standard license. Click here to learn more if you are interested in processing your runs on more than 2 cores.)

Please follow the steps below to setup the parallel processing capability on your computer.

Install BREEZE AERMOD Parallel

  1. In order to use the parallel processing feature in BREEZE AERMOD, you need to first install BREEZE AERMOD Parallel separately from the installation of BREEZE AERMOD. The BREEZE AERMOD Parallel Installation Guide can be found on the homepage of BREEZE AERMOD:

    BREEZE AERMOD - Home Page

  2. Please follow the installation guide step by step carefully, as any misstep could influence subsequent steps. In the last validation step, please make sure you see SUCCESS as highlighted below in the Command Prompt dialog (the screenshot is taken from the BREEZE AERMOD Parallel installation on the 64-bit operating system):

    Administrator_Command Prompt_Success

    As U.S. EPA released both a 64-bit and 32-bit version for AERMOD v19191, please make sure to install both the 64-bit and 32-bit version of BREEZE AERMOD Parallel following the installation guide.

Run the Model Using BREEZE AERMOD Parallel

  1. After the successful installation of BREEZE AERMOD Parallel, when you want to use the parallel processing feature to run certain model, you will need to first check the “Use Parallel” box in Control Options.

    Control Options

  2. Then in the Model Run dashboard, you should be able to select more than one processor to use for the model run under Parallel Processor Settings. As was mentioned above, every copy of BREEZE AERMOD comes with a complimentary license of the 2-processor version of BREEZE AERMOD Parallel. If you need a BREEZE AERMOD Parallel version with more than two processors, you can purchase a BREEZE AERMOD Parallel license through the BREEZE Sales Team.

    Please be aware that because U.S. EPA released a 64-bit and 32-bit version for AERMOD v19191, if you are running the model using an AERMOD version later than 19191, you will need to select the corresponding version of BREEZE AERMOD Parallel that you want to use as highlighted below.

    BREEZE Dashboard

Common Problems & Solutions

  1. If BREEZE AERMOD crashes as shown in the screenshot below, please double check that you have installed the selected version of BREEZE AERMOD Parallel. In this case, only the 32-bit BREEZE AERMOD Parallel has been installed but the 64-bit BREEZE AERMOD Parallel version is selected to run the model, which causes BREEZE AERMOD to crash.

    BREEZE Dashborad_Error message

  2. In the Model Run dashboard, after you click “Start” to run the model, if a similar error message is displayed as: “Credentials for … rejected connecting to …” or “User credentials needed to launch processes …”, please repeat the step of Account Registration and Testing in the BREEZE AERMOD Parallel Installation Guide. BREEZE AERMOD Parallel needs to be registered under a certain user account. If for some reason the user credentials are changed/removed, you will need to re-register.

    Administrator_Command Prompt_Registration

If you have questions when installing BREEZE AERMOD Parallel or when using it for your AERMOD model runs, please contact the BREEZE Support Team via email at or phone +1 (972) 661-8881 ext. 4 and it will be our pleasure to assist you.

Note: Before submitting any AERMOD runs that were parallel processed to an agency for regulatory purposes, check with the agency to ensure results will be accepted.