DEVELOPMENT OF A NUMERICAL-INTEGRATION AREA SOURCE ALGORITHM FOR INDUSTRIAL SOURCE COMPLEX LONG-TERM (ISCLT) MODEL

The Previous model evaluation studies have shown the deficiencies of t he virtual point source algorithm for modeling area sources used in th e ISCLT2 model. This paper documents the development, testing, and eva luation of a new numerical integration algorithm for modeling area sou rce for the ISCLT2 model. This algorithm, which is based on the numeri cal integration for area source recently implemented in the ISCST2 mod el, allows users to handle the complex geometry of irregularly shaped area sources, and allows the calculation of the area source impact for receptors located within and nearby the area source. Detailed perform ance tests, statistical analyses, and sensitivity analyses have been c ompleted to assure the reliability and reasonableness of the modeling results. The algorithm has been compared with the currently used ISCLT 2 virtual point source algorithm, as well as with the numerical integr ation area source algorithm for the ISCST2 model. The results show tha t the new numerical integration ISCLT2 area source algorithm performs very well. Using idealized meteorological conditions, the new algorith m achieves very good comparison results when compared with the newly d eveloped ISCST2 area source algorithm. It is also concluded that the c urrently used ISCLT2 area source algorithm based on the virtual point source approach underestimates the concentration value by a factor of about 2 or 4, especially when the receptors are located inside or near the source.