DISSEMINATION OF PROTOCOL FOR COMPARING AIR DISPERSION MODELS

ARCHIVE OF PROTOCOL FOR COMPARING AIR DISPERSION MODELS

1. Introduction

In 1998 the UK Environment Agency commissioned a study to assess the AERMOD model for regulatory purposes in the UK and its performance in relation to the other advanced dispersion model in UK use, ADMS. Until the appearance of AERMOD, recent UK regulatory practice had been mainly based on ADMS and the use of a second major advanced model would raise regulatory problems if these two models performed differently. The study had three main objectives. Firstly to review past intercomparison studies of these advanced dispersion models in relation to the older Pasquill/Gifford types of model. Secondly, to develop a protocol for model assessment which could be used in this assessment and which would provide a consistent framework for future assessment of models for regulatory purposes. Thirdly, to compare the performance of AERMOD with ADMS and the older Pasquill/Gifford models and assess its performance for use in regulation.

This archive has been prepared in the interests of disseminating the test protocol as widely as possible and encouraging its further use, so that a historical perspective of dispersion model performance can be developed. It contains everything required to carry out further calculations with new models or revised versions of the ADMS or AERMOD models. It includes,

Copies of the original Environment Agency intercomparison reports and Technical summary (Section 2).
Input and ouput files for all the model calculations carried out in the study (Section 3).
The meteorological data sets needed for the calculations; in the formats provided both directly by the UK Meteorological Office and via Trinity Consultants (Section 4).
The terrain data files used in the study (Section 5).
Other relevant papers related to the study (Section 6).
The ADMS model developer’s (CERC) comments on the study and the authors’ reply, together with a discussion of the use of dispersion models in regulatory practice (Section 7).

The model assessment protocol includes test cases using single weather conditions and using hourly annual weather data, the form in which regulatory assessments are usually made. The input and output data files for each model calculation in the intercomparison are available to download and details are given in the following sections. Also available are the meteorological data files for the particular site and year used in the study. These have been kindly made available by the UK Meteorological Office and by Trinity Consultants Ltd.