Stability of Atmospheric Teleconnections in Dynamical Models

Recent observational studies have shown various patterns of atmospheric teleconnection of seasonal circulation anomalies between the poles and regions further afield, ranging from the sub-polar and mid-latitude regions to the tropics. These atmospheric teleconnection patterns have been evoked as links to explain observed co-variability between various surface climate variables in different regions, such as Arctic sea ice and tropical Pacific SSTs or northern hemisphere winter conditions, yet their study is constrained by the limited duration of the observational record, particularly in the high latitudes. In this work we assess the presence and stability of regimes of atmospheric teleconnection patterns that originate both in the poles and tropics in long control runs of dynamical models and in the CESM Large Ensemble. We find a rich spectrum of variability in the strength of teleconnection patterns, with decadal periods of strong Arctic – tropical teleconnections interspersed with decadal periods of weak or no teleconnections, while southern hemisphere – tropical teleconnections tend to be more robust. Furthermore, teleconnection patterns only stabilize when centennial or longer time-periods are used for their calculation. To the extent that such behavior is realistic, we discuss the implications our results have for the use of statistical models in seasonal forecasts and in the detection and attribution of observed changes in co-variability.