Gaussian air dispersion models are widely used for short-range pollutant dispersion study. In Hong Kong, ISC, an old-generation model is recommended in the environment impact study while there is advance generation of models grown in much interest in environmental field. The objective of this study is to investigate how Gaussian air dispersion models perform under Hong Kong scenario in order to find out which model would be the best candidate for replacement and at the same time provide some guidelines on applying Gaussian air dispersion models....[ Read more ]

Gaussian air dispersion models are widely used for short-range pollutant dispersion study. In Hong Kong, ISC, an old-generation model is recommended in the environment impact study while there is advance generation of models grown in much interest in environmental field. The objective of this study is to investigate how Gaussian air dispersion models perform under Hong Kong scenario in order to find out which model would be the best candidate for replacement and at the same time provide some guidelines on applying Gaussian air dispersion models.

In this study, four Gaussian air dispersion models, namely ISC3, AUSPLUME (two old- generation models), AERMOD and ADMS (two advance models) are examined under Hong Kong meteorological conditions in two cases of study, one is the Hong Kong International Airport and the other one is the Castle Peak power plant. The results showed that these four models never agreed in the modeling results, due to various implementations of the dispersion equation and the meteorological processor. Advance models are preferred to the old ones due to better meteorological sense, discrete P-G stability class vs. continuous stability. Between the advance ones, ADMS is recommended over AERMOD due to several reasons. Firstly stability parameter estimated by ADMS’ meteorological pre-processor matched better with the observed stability than the one by AERMOD’s meteorological pre-processor, which is a crucial parameter in determining the dispersion parameters. Secondly, ADMS provides more functionality in modeling dispersion in urban region for instance setting minimum M-O length and street canyon model.