Comparison of estimated concentrations using ISC-PRIME versus ISCST-3

Conference · Thu Jul 01 04:00:00 EDT 1999

OSTI ID:20002124

Morrison, K

Shortcomings in the building downwash algorithms within ISCST-3 led to the development of the PRIME algorithm. Recently a version of ISCST with PRIME embedded in place of the previous algorithms was made available on the SCRAM website for public examination. To date, comparative evaluation studies of PRIME versus the current algorithms were limited to relatively simple stack and building situations. The authors carried out a qualitative comparison for actual large sites of concentrations estimated using ISCST-3 or the version of ISCST with the downwash algorithms replaced with PRIME (ISC-PRIME). Two large industrial sites were examined, one in flat terrain and the other in intermediate/complex terrain. For each site two meteorological datasets were used: an artificial set applying screening meteorological data combinations at 5 increments over the full 360, and the actual meteorological data as had been used for permitting at these sites. For the site in flat terrain ISC-PRIME found generally lower 1-hour concentrations than ISCST-3, especially under stable and very stable conditions, but longer term averages were very similar. For the site in complex terrain, the two models found very similar results due to the dominance of volume sources not affected by downwash. However, for the point sources alone ISC-PRIME found higher concentrations than ISCST-3, especially for those receptors on elevated terrain, and this for all averaging periods. This latter difference was not due to elevations, but was instead due to the plant layout because when the models were re-run in flat mode ISC-PRIME still estimated higher maximum concentrations. Thus the use of PRIME will not consistently estimate either higher or lower concentrations than the usual algorithms, but results will be sensitive to plant layout.

• Research Organization: Environmental Modeling, Montreal, Quebec (CA)
• OSTI ID: 20002124
• Report Number(s): CONF-990608--
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AIR POLLUTION
COMPARATIVE EVALUATIONS
ECOLOGICAL CONCENTRATION
I CODES
INDUSTRIAL WASTES
METEOROLOGY
P CODES