ADMS 4

State-of-the-art modelling of industrial air pollution

What is ADMS 4?

ADMS 4 is a dispersion model used to model the air quality impact of existing and proposed industrial installations. Current and future air quality can be assessed with respect to the air quality standards such as the EU Air Quality Directive, UK Air Quality Strategy, US National Ambient Air Quality Standards (NAAQS), Chinese Class I, II and III and WHO guidelines.

Typical applications include:

• permitting/IPPC authorisations,
• stack height determination,
• odour modelling,
• environmental impact assessments and
• safety and emergency planning.

Who uses ADMS 4?

The dispersion model ADMS 4 is currently used in many countries worldwide. Users of ADMS 4 include:

• over 130 individual company licence holders in the United Kingdom,
• regulatory authorities including the UK Health and Safety Executive (HSE),
• Environment Agency in England and Wales,
• Scottish Environmental Protection Agency (SEPA) in Scotland,
• Environment and Heritage Service in Northern Ireland,
• government organisations including the Food Standards Agency (United Kingdom),
• users in other European countries, Asia, Australia, North America and the Middle East.

Why use ADMS 4?

ADMS 4 is a new generation Gaussian plume air dispersion model, which means that the atmospheric boundary layer properties are characterised by two parameters:

• the boundary layer depth, and
• the Monin-Obukhov length

rather than in terms of the single parameter Pasquill-Gifford class.

Dispersion under convective meteorological conditions uses a skewed Gaussian concentration distribution (shown by validation studies to be a better representation than a symmetrical Gaussian expression).

The ADMS 4 model includes:

Model options	ADMS 4 has a number of model options including: dry and wet deposition; NOx chemistry; impacts of hills, variable roughness, buildings and coastlines; puffs; fluctuations; odours; radioactivity decay (and γ-ray dose); condensed plume visibility; time varying sources and inclusion of background concentrations.
Meteorological pre-processor	ADMS 4 has an in-built meteorological pre-processor that allows flexible input meteorological data both standard and more specialist. Hourly sequential and statistical data can be processed, and all input and output meteorological variables are written to a file after processing.
User-defined outputs	The user defines the pollutant, averaging time (which may be an annual average or a shorter period), which percentiles and exceedence values to calculate, whether a rolling average is required or not and the output units. The output options are designed to be flexible to cater for the variety of air quality limits, which can vary from country to country, and are subject to revision.
Visualisation	ADMS 4 includes the ADMS Mapper: an integrated mapping tool for displaying and editing source data, buildings and receptor locations and viewing results. The model has links to the Surfer contour-plotting package, in addition to ArcGIS and MapInfo Professional Geographical Information System (GIS) software. The GIS links can be used to enter and display input data, and display output, usually as colour contour plots.
Terrain converter	Utilities for creating terrain files for the United Kingdom, France, Northern Ireland, Republic of Ireland and the US can either be accessed directly from the ADMS 4 interface, or are freely downloadable from the user area.

ADMS versus other models

	ADMS 4	AERMOD	ISC
Meteorology
Meteorological pre-processor
Dispersion
Boundary-layer structure	h, LMO scaling	h, LMO scaling	Pasquill stability classes
Plume rise	Advanced integral model	Briggs empirical expressions	Briggs empirical expressions
Concentration distribution	Advanced Gaussian	Advanced Gaussian	Basic Gaussian
Complex effects
Buildings	ADMS buildings module	PRIME buildings module	PRIME buildings module
Complex terrain	Based on calculation of flow field and turbulence field by FLOWSTAR model	Interpolation between neutral flow approximate solution and stable flow impaction solution	Simple approach assuming plume trajectory unaffected by terrain
Deposition (wet and dry)
Chemistry	Generic Reaction Set 8 reaction scheme	Ozone limiting model, assumes maximum conversion of NO to NO2	Ozone limiting model, assumes maximum conversion of NO to NO2
Other options
Fluctuations
Visible plumes	Condensed plume visibility
Radioactivity	Radioactive decay / γ-ray dose; decay chain database	Simple decay	Simple decay
Puff model
Coastline module
Input of vertical profiles of meteorological data