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Bayesian uncertainty estimation methodology applied to air pollution modelling.

Romanowicz, Renata and Higson, Helen and Teasdale, Ian (2000) Bayesian uncertainty estimation methodology applied to air pollution modelling. Environmetrics, 11 (3). pp. 351-371.

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Abstract

The aim of the study is an uncertainty analysis of an air dispersion model. The model used is described in NRPB-R91 (Clarke, 1979), a model for short and medium range dispersion of radionuclides released into the atmosphere. Uncertainties in the model predictions arise both from the uncertainty of the input variables and the model simplifications, resulting in parameter uncertainty. The uncertainty of the predictions is well described by the credibility intervals of the predictions (prediction limits), which in turn are derived from the distribution of the predictions. The methodology for estimating this distribution consists of running multiple simulations of the model for discrete values of input parameters following some assumed random distributions. The value of the prediction limits lies in their objectivity. However, they depend on the assumed input distributions and their ranges (as do the model results). Hence the choice of distributions is very important for the reliability of the uncertainty analysis. In this work, the choice of input distributions is analysed from the point of view of the reliability of the predictive uncertainty of the model. An analysis of the influence of different assumptions regarding model input parameters is performed. Of the parameters investigated (i.e. roughness length, release height, wind fluctuation coefficient and wind speed), the model showed the greatest sensitivity to wind speed values. A major influence on the results of the stability condition specification is also demonstrated.

Item Type: Article
Journal or Publication Title: Environmetrics
Uncontrolled Keywords: Gaussian air dispersion model ; sensitivity analysis ; Bayesian uncertainty estimation ; likelihood functions ; prior and posterior probability density functions ; prediction errors ; prediction limits
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 21659
Deposited By: ep_ss_importer
Deposited On: 23 Jan 2009 13:44
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 15:50
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/21659

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