OZONE PERTURBATIONS

One clear limitation of most of the models is that they have little or no representation of explicit stratospheric chemistry. This could also clearly limit the models ability to predict the full atmospheric impact on ozone of aircraft emissions since it is predicted by the models that approximately 1/3 of the ozone perturbations occur in the lower stratosphere. 

Obviously the models used in this study have clear limitations with regard to predicting aircraft impact on atmospheric ozone. Nevertheless, they should give a good indication of the expected impact. The range of results presented is what one would expect in ozone perturbations from aircraft due to the large differences in model formulations and parameterisation s in the models. 

A key question when future ozone perturbations from NOx emissions are studied is the question of non linearity. Will the ozone production become less efficient per NOx molecule emitted for high NOx emissions from aircraft, or in an environment with higher background levels of NOx which we will have in the future due to higher surface NOx emissions The non linearity in ozone production is shown in Tale 5 below... 

In individual sensitivity studies where two or several models participated, it was demonstrated that there are differences in the model results, reflecting differences in model formulations of chemical and dynamical processes. A main conclusion of the study is that the uncertainty range of the model estimates of large-scale ozone perturbations is approximately a factor two. 

OZONE PERTURBATION (ppbv) WATER VAPOR PERTURBATION (%)... 

Crutzen, P.J., and C.T. Howard, Effect of the HO2 + NO reaction rate constant on one-dimensional model calculations of stratospheric ozone perturbations. Pure Appl Geophys 116, 497, 1978. 

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