Prospects and limitations of seasonal atmospheric GCM predictions

Abstract

Climate simulations of increasingly large ensemble sizes are being performed to determine the predictive capability of atmospheric general circulation models (AGCMs) on seasonal or longer timescales. These have exhibited large sensitivity to anomalous boundary forcing associated with global sea surface temperatures (SSTs). These issues are addressed within the context of a large ensemble of climate simulations using an AGCM forced with observed SSTs for the 1982-93 period. From the analysis of the model data it is argued that the impact of interannual changes in SSTs is to create a shift in the extratropical-mean state, although this shift is small and resides within the envelope of atmospheric states attained with climatological SSTs. -from Authors