Evolution of perturbations in 3D air quality models

The deterministic approach of sensitivity analysis is applied on the solution vector of an Air Quality Model. In
particular, the photochemical CAMx code is augmented with derivatives utilising the automatic differentiation
software ADIFOR. The enhanced with derivatives version of the model is then adopted in a study of the effect of
perturbations at the boundary conditions on the predicted ozone concentrations. The calculated derivative matrix
provides valuable information e.g., on the ordering of the infl uential factors or the localisation of highly affected
regions. Two fundamentally different domains of the Auto-Oil II programme were used as test cases for the
simulations, namely Athens and Milan. The results suggest that ozone concentration be highly affected by its own
boundary conditions and subsequently, with an order of magnitude less, by the boundary conditions of NOX and VOC.