MODEL
INPUTS
Source parameters
include:
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source location data,
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road widths and canyon heights for road sources,
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stack heights, diameters, exit velocities etc
for industrial sources.
Once source data have been loaded into the model, users
can use the GIS link to view the sources as the part of the input
data validation process. For example, the picture below shows all
the sources from an example modelling scenario: industrial point sources
and roads, displayed using the ArcView link. Note the additional GIS
tools for use with ADMS-Roads. The point and road sources are shown
in the display.
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For road sources, the user can enter hourly speed and traffic
flow data into the model and use
ADMS-Roads’s built-in emission factors to calculate pollutant
emission rates, or, alternatively, the user can enter pre-calculated
pollutant emissions data, for example, emissions calculated within
CERC’s Emissions Inventory Toolkit, EMIT,
which includes many factors such as current and future factors for
Euro standard engines.
Modelling roads in urban areas is more complex than
just modelling the emissions from traffic as a line source. Both the
effect of street canyons, and traffic-induced
turbulence are included when roads are modelled in ADMS-Roads.
When modelling any local emissions, it is important to include the background
concentrations - both ambient concentrations
that are advected from outside the modelling area, and those that occur
due to local emissions that are not explicitly modelled. In the UK,
ambient background data can be downloaded from the UK National Air Quality
Archive website (http://www.airquality.co.uk/archive/index.php)
and included directly in any ADMS-Roads modelling scenario. In ADMS-Roads,
background concentrations should be hourly values. If these are not
available, constant values can be assumed, but use of an hourly background
is preferable.
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