Using ERA-Interim Reanalysis data, it is shown that teleconnections play a crucial role in driving Arctic Amplification, i.e., the inter-decadal warming of the Earth’s surface being largest in the Arctic. It is shown that teleconnections that are excited by tropical convection and constructively interfere with the climatological stationary eddies organize synoptic-scale storms in a manner that leads to a large transport of water vapor into the Arctic via atmospheric rivers. The subsequent condensation and latent heat release are followed by an increase in downward infrared radiation at the surface. This process is shown to be the main driver of Arctic Amplification and to account for the majority of sea ice loss. Self-organizing maps (SOMs) are used to show that the majority of the inter-decadal trend in the atmospheric circulation can be understood as arising from inter-decadal changes in the frequency of occurrence of intra-seasonal teleconnections. Applications from the impact of stratospheric ozone loss and greenhouse gas driving are presented.
The sensitivity of extratropical teleconnections to the detailed structure of tropical convection is investigated. Both ERA-Interim Reanalysis data and data from idealized climate model runs are used. It is found that teleconnections such as the Pacific/North American pattern particularly sensitive to the relative amplitude of amplitude of convective heating anomalies in the western and central tropical Pacific. Relatively small changes in the amplitude of convective heating anomalies can result in a change in sign of the anomalies that comprise extratropical teleconnection or can even suppress the occurrence of teleconnections.
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