Model Guidelines

Revision of Guidelines for Short Range Dispersion Modelling of Releases to Atmosphere from Industrial Sources

The Atmospheric Dispersion Modelling Liaison Committee feels that some applications of atmospheric dispersion models are inadequate, and that this may reflect a lack of appropriate guidance/training in Atmospheric Dispersion Modelling. ADMLC considers that publication of up to date guidance on Dispersion Modelling may be one way to facilitate possible improvement in applications although this cannot be a replacement for proper training.

The Royal Meteorological Society (RMetS) produced a set of guidelines in 1995 which were intended to promote the use of best practice in the use of mathematical models of atmospheric dispersion, emphasising the principle of fitness for purpose in the selection of modelling procedures, and the importance of effective communication in the documentation of reported results. The underlying objectives are to ensure the efficient use of resources, especially in the context of assessments conducted for purposes of demonstrating compliance with regulatory obligations.

The RMetS guidelines set down general principles of good practice for the design, execution and communication of modelling studies, focussing on broad principles which apply across a wide range of environmental modelling situations.

They did not try to give situation-specific technical advice, e.g. how to model a dense gas spill, or which plume rise formula to use. Instead, they tried to identify and expound certain principles of good practice which apply to many modelling situations.

ADMLC feels that sufficient time has passed since the RMS guidelines were prepared, and that modelling techniques have evolved over the intervening period, that there is merit in preparing further guidelines which will update, extend and complement, rather than replace, the existing ones. This guidance is intended to improve the robustness of assessments by providing advice on addressing the scope of the assessment, selecting and justifying an appropriate model and effective communication in the documentation of reported results. It follows the same structure and uses the same section headings as the original RMetS guidance.

The RMetS has agreed to the preparation of this revised guidance.

A draft version of the revised guidelines was placed on the ADMLC web site for comment. The final version of the guidelines, Dispersion model guidelines – V1-5, responds to the comments received.