Uncertainties in photochemical grid modeling of ozone. The impact of uncertainties in meteorological inputs

Eulerian photochem. grid models are widely used in the making of policy decisions concerning emission controls. However, significant uncertainties persist in a host of crucial input parameters. Quantifying and understanding their implications have become imperative from both the scientific and policy perspectives. Meteorol. uncertainties have a special significance because efforts to quantify them using conventional techniques based on expert ests. have failed to account for the complex correlations in their nonlinear spatial and temporal evolution. A comprehensive effort to quantify meteorol. uncertainties has been accomplished by subjecting a mesoscale meteorol. model to Monte Carlo simulations based on uncertainties in key base input parameters for the 3-day summer smog POLLUMET episode over the Swiss plateau. Monte Carlo uncertainty anal. based on the resulting meteorol. input uncertainties was then carried out using a photochem. grid model. Preliminary post-simulation anal. and statistics on the uncertainties in peak ozone estn. and the significance of considering correlations among inputs in sampling are presented.