Seminar: Sensitivity Analysis of Air Pollution Models

Speakers: Rayna Georgieva and Sofiya Ivanovska,

IPP, Bulgarian Academy of Sciences.

Date/Time: 13th November 2008, 13:00-14:00.

Location: Room G74, Philip Lyle Building.

Map: http://www.info.rdg.ac.uk/maps/maps-display.asp

Abstract:

In our days people face a lot of serious challenges like environmental security that is according to a statement within the NATO Science Forum (taken place in March 2008) the common ground of the mutual interest of security and environment and has a strategic role for a stability of contemporary society. The increasing importance of these two major topics fairly explains sufficient impact of environmental modeling, and in particalar air pollution modeling, for development of monitoring and control strategies of levels of pollutants concentrations.

A systematic procedure for a sensitivity analysis of a case study in the area of air pollution modeling has been performed. Contemporary mathematical models should include a large set of chemical and photochemical reactions to be established as a reliable simulation tool [1]. The Unified Danish Eulerian Model (UNI-DEM) is in the focus of our investigation as one of the most advanced large-scale mathematical models that describes adequately all physical and chemical processes. Variance-based methods are one of the most often used approaches for providing sensitivity analysis. To measure the extent of influence of the variation of the chemical rate constants in the mathematical model over the pollutants concentrations the global (Sobol’) sensitivity indices are estimated using efficient techniques for small sensitivity indices to avoid a loss of accuracy described in [2]. A comparison with results obtained using an environment for statistical computing has been done. Studying of relationships between input parameters and model output and internal mechanisms is very useful for a verification and an improvement of the model and therefore for a reliable prediction of the final output of scenarios when the concentration levels of pollutants are exceeded. The proposed procedure can also be applied when other large-scale mathematical models are used.

[1] Z. Zlatev, I. Dimov, and K. Georgiev, Modeling the Long-Range Transport of Air Pollutants, IEEE Computational Science and Engineering, Vol. 1 (3) (1994), 45-52.

[2] I. Sobol’, E. Myshetskaya, Monte Carlo Estimators for Small Sensitivity Indices, Monte Carlo Methods and Applications, Vol. 13 (5-6) (2007), 455-465.