One of the most important advanced modules in ADMS-Airport is the chemistry module. The following options are available:
Other advanced modules are:
These modules are based on the latest understanding of the way these features affect the movement of airflow around the sources, and all have been shown to have considerable affect on observed concentrations.
ADMS-Airport models NOx chemistry using the 8 reaction Generic Reaction Set (Venkatram et al., 1994) that includes reactions with ozone and hydrocarbons.
In most urban areas, the dominant pollution source is road traffic, and the pollutants usually of major interest are NOx and PM10. The NOx chemical reactions take place over a relatively short time period and in order to get accurate predictions of NO2 concentrations, NOx chemistry should be taken into account. The Generic Reaction Set predicts changes in ozone concentrations that are also of interest.
A simple Lagrangian Trajectory Model is used to calculate background concentrations for the air approaching the main modelling area. This model includes the effects of emissions, chemistry, deposition and ozone entrainment.
By nesting the main model domain within a larger domain, such as a large urban conurbation, the Trajectory Model calculates a spatially varying background ambient concentration that takes into account the chemical reactions and processes occurring over the larger domain.
The reactions between SO2 and other compounds in the air to produce particulates are based on those used in the EMEP model (Tsyro, 2001).
These reactions have a significant effect on the concentrations of particulates in areas where there are a large number of industrial sources emitting SO2 or downwind from a large emitter of SO2.
This module is based on the Danish Operational Street Pollution Model (OSPM, Hertel and Berkowicz, 1990, Hertel et al., 1990).
Users can include the effect of up to 10 dominant buildings on point source emissions. ADMS-Airport creates an effective building for each point source from the user-defined buildings and models the re-circulating flow in the lee of the building, the cavity region, as well as the building main wake.