The Industrial Source Complex Short Term (ISCST3) model is the US EPA’s current regulatory model for many New Source Review (NSR) and other air permitting applications. The ISCST3 model is based on a steady-state Gaussian plume algorithm, and is applicable for estimating ambient impacts from point, area, and volume sources out to a distance of about 50 kilometers. ISCST3 includes algorithms for addressing building downwash influences, dry and wet deposition algorithms, and also incorporates the complex terrain screening algorithms from the COMPLEX1 model.
The ISCST model was originally developed in the 1970’s. The ISCST2 model was developed by PES under contract to the US EPA between 1989 and 1992, and represented a major restructuring and reprogramming of the model code. PES has continued to support EPA’s maintenance and further development of the ISCST3 model for the past decade. Major enhancements to the model that were implemented by PES include an improved area source algorithm, the complex terrain screening algorithms from COMPLEX1, a revised dry deposition algorithm, a wet deposition algorithm, a pit retention algorithm, conversion of the code to Fortran 90, and several enhancements and optimizations intended for air toxics applications. The conversion of the code to Fortran 90 allowed the introduction of dynamically allocatable array storage so that users no longer need to recompile the model to modify the limits on the number of sources, receptors, etc., that can be modeled.
The ISCST3 model utilizes hourly meteorological data that have been preprocessed using the PCRAMMET program for National Weather Service (NWS) data, and the Meteorological Processor for Regulatory Models (MPRM) for on-site data.
The US EPA is proposing the AERMOD and ISC-PRIME models as replacements for ISCST3 at the upcoming 7th Modeling Conference, scheduled for June 28-29, 2000 in Washington, DC.
You can download the current version of ISCST3 here, including source code, executable, test case, and user’s guide:
For more information on the ISCST3 model, visit PES’ Frequently Asked Questions (FAQs) on ISCST3, or contact PES at Roger.Brode@pes.com.