One of the most important advanced modules in ADMS-Roads 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-Roads models NOx chemistry using the 8 reaction Generic Reaction Set (Venkatram et al., 1994) that includes reactions with ozone and hydrocarbons.
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.
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.
'Street canyons' are defined as the deep, narrow, valley-like spaces created when a road is enclosed by tall buildings on both sides. High pollution levels are often observed in street canyons. The street canyon module included within ADMS-Urban/Roads is based on the Danish Operational Street Pollution Model (OSPM, Hertel and Berkowicz, 1990, Hertel et al., 1990).
This module is based on FLOWSTAR advanced airflow model which calculates the change in mean flow and turbulence due to terrain and changes in surface roughness (land use).
Users can include the effect of up to 25 dominant buildings on point source emissions. ADMS-Roads Extra 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.