Atmospheric modelling of air pollution as a tool for environmental prediction and management

HIRES is a high resolution mesoscale atmospheric modelling system to which has recently been added an atmospheric pollutant dispersion and chemical reaction module. This module, referred to as AIRCHEM, has a set of transport (advection), diffusion, deposition and chemical reaction components. The coupled HIRES-AIRCHEM system can be applied to local intra-regional problems, as well as to inter-regional and long-range air quality problems. The AIRCHEM component is in a relatively early stage of development and as yet has only a simple chemical scheme comprising 10 chemical species. In this study the coupled HIRES-AIRCHEM system is tested on three distinct problems. The first problem is an ozone event over the Sydney, New South Wales (NSW) basin. This is an intra-regional example in which the NSW Environment Protection Authority's ozone concentration health limit of 10 pphm was attained or exceeded over a large section of the Sydney basin. The second case is an inter-regional one in which smoke from a prescribed burn ignited well to the north of Sydney was transported over the Sydney basin. A regional pollution index (RPI) was recorded that was more than four times the NSW Environmental Protection Authority (EPA) health limit. Finally, the third case presented here is one of long range transport of smoke particulates over southeast Asia, from the massive fires that occurred during the 1997/1998 El Nino episode. The results obtained from these three very distinct cases were sufficiently encouraging to suggest that the coupled HIRES-AIRCHEM system should prove to be a powerful tool in assisting environmental management and emergency policy in the air quality arena.