Principal modes of atmospheric variability in model atmospheres with and without anomalous sea surface temperature forcing in the tropical Pacific.

Abstract

Principal modes of low-frequency atmospheric variability and the influence of sea surface temperature anomalies on such modes are investigated by examining the output from two general circulation model experiments. The analysis tools employed here include empirical orthogonal functions, teleconnections and composite charts. Two prominent modes of variability have been identified in the wintertime Northern Hemisphere eddy stream function of the SST experiment. The first mode bears a strong spatial resemblance to the observed characteristic circulation pattern over the North Pacific-North American sector. The second mode exhibits no significant correlation with the SST forcing, but is linked instead to a characteristic structure of the zonally averaged zonal wind.-from Authors