Changes in the NAO distribution in high resolution PRUDENCE time-slice climate change experiments

We present results from ensembles of high resolution PRUDENCE time-slice experiments performed with the NASA finite volume atmospheric general circulation model (FVGCM). In particular we investigate how the probability density function of the North Atlantic Oscillation (NAO) is modified in A2 scenario experiments as compared with experiments for current climate. We find that the mean change in winter 500 hPa height projects onto the positive NAO phase and that this is due to an increase of strong NAO events, whereas the frequency of near-neutral NAO events remains almost unchanged. These extreme NAO events are accompanied by strongly increased storm activity over Europe. Composites of relevant fields of these strong NAO events are presented and possible mechanisms of the changed NAO distribution are discussed.