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 statistica l significance of the climatic impact a multivariate statistical test hierarchy combined with the fingerprint method has been applied. Our s ensitivity experiments suggest the existence of a coherent temperature response pattern for northern hemisphere summer conditions. The signa l is highly significant in case of an artificially enhanced forcing, b ut it retains its characteristic structure for present-day forcing con ditions, when statistical significance becomes more moderate. The sign al consists of a tropospheric warming of about 0.2 K and a correspondi ng stratospheric cooling of similar magnitude.