The linearity of the atmospheric response to North Atlantic sea surface temperature anomalies

A large number of uncoupled integrations with an idealized general circulation model are carried out to investigate the linearity of the atmospheric quasi-equilibrium response to North Atlantic sea surface temperature (SST) anomalies related to interdecadal variability. A statistical approach is used to judge the linearity of the temporally averaged global atmospheric response with respect to the amplitudes of the SST anomaly patterns. The results indicate that the assumption of a linear correlation of the corresponding magnitudes is, in general, not valid. Since the model, though idealized, provides all the characteristics of a full general circulation model (GCM), some important conclusions can be drawn for the design and interpretation of GCM sensitivity experiments.