Simulating the response of stratospheric ozone to specified increases in greenhouse gas concentrations between 1979 and 2060

While chlorine loadings in the atmosphere are expected to decrease towards pre-ozone hole levels by 2060, the greenhouse gases (GHGs) burden is rising continuously and may in turn modify significantly the stratospheric ozone layer. In this study, the response of stratospheric ozone to increases in greenhouse gas concentrations between 1979 and 2060 is investigated using the new interactively coupled chemistry - general circulation model IGCM-FASTOC. The IGCM (Intermediate General Circulation Model) is a relatively fast general circulation model (GCM) with parameterizations of an intermediate level of complexity, and the new chemistry scheme FASTOC (Fast STratospheric Ozone Chemistry) is an efficient input-output model composed of precomputed non-linear functions.

Multiple time-slice simulations are performed to allow for the quantification of individual processes involved in the response of stratospheric ozone. In the talk, emphasis will be placed upon the sensitivity to increases in methane and water vapour.