Future changes in Major Stratospheric Warmings in CCMI models
In this study, future changes in wintertime Arctic stratospheric variability are examined in order to obtain a more precise picture of future changes in the occurrence of MSWs. In particular, transient REF-C2 simulations of different CCMs involved in the Chemistry Climate Model Initiative (CCMI) are used. These simulations extend from 1960 to 2100 and include forcings by halogens and greenhouse gases following the specifications of the CCMI-REF-C2 scenario. Sea surface temperatures (SSTs) and sea-ice distributions are either prescribed from coupled climate model integrations or calculated internally in the case of fully coupled atmosphere-ocean CCMs. Potential changes in the frequency and main characteristics of MSWs in the future are investigated with special focus on the dependence of the results on the criterion for the identification of MSWs and the tropospheric forcing of these phenomena.
Our preliminary results do not show, in general, a statistically significant future change in the mean frequency of MSWs by using the standard criterion for the identification of MSWs. However, future seasonal changes in the intensity of the polar night jet are found but they differ among model.