Climatic impact of aircraft induced ozone changes

The effect of aircraft induced ozone changes on the global climate is studied by means of the general circulation model ECHAM4. We focus on the zonal mean temperature signal. In order to estimate the statistical significance of the climatic impact a multivariate statistical test hierarchy combined with the fingerprint method has been applied. Our sensitivity experiments suggest the existence of a coherent temperature response pattern for northern hemisphere summer conditions. The signal is highly significant in case of an artificially enhanced forcing, but it retains its characteristic structure for present-day forcing conditions, when statistical significance becomes more moderate. The signal consists of a tropospheric warming of about 0.2 K and a corresponding stratospheric cooling of similar magnitude.