Andrew Charlton

Columbia University

Lorenzo Polvani

Recent research has highlighted the potential role of stratospheric variability in the tropospheric climate system (Baldwin and Dunkerton, 2001). We would like to validate the representation of stratospheric variability, and in particular stratospheric sudden warmings in some of the AR4 simulations. We recognise that many of the AR4 models have only a limited representation of the stratosphere. However we feel that quantifying the degree to which these models represent stratospheric variability is an important in understanding to what extent coupled stratosphere-troposphere dynamics are represented in the AR4 models. We have calculated a new climatology of stratospheric sudden warmings from reanalysis datasets using a new diagnostic algorithm which we would hope to apply to the climate of the 20th century simulations in the AR4 dataset.