ASSESSMENT OF THE FUTURE-DEVELOPMENT OF THE OZONE-LAYER

ECHAM3/CHEM is used to estimate the future development of the ozone la yer. The general circulation model ECHAM3 and the chemistry module CHE M are coupled in a CTM-like mode, i.e. no feedback of simulated chemic al species on radiation is considered. Currently CHEM does not include bromine chemistry. Two time-slice experiments representing 1991 and 2 015 conditions are carried out. Chemical species are transported by wi nds calculated with different CO2 mixing ratios as a proxy for other g reenhouse-gases. For 2015, the adopted increase of CO2 and the corresp onding modification of the sea-surface temperature lead to a warming o f the troposphere and a cooling of the stratosphere. The assessment fo r 2015 indicates that the ozone layer will not homogeneously recover, despite the employed decrease of chlorine in the model. Whereas in low and mid-latitudes an ascent of stratospheric O-3 is obvious, no signi ficant increase of O-3 is found in the polar regions during spring tim e.