Tropical rainfall linked to stronger future ENSO-NAO teleconnection in CMIP5 models

The El Niño-Southern Oscillation (ENSO) has previously been shown to influence the winter North Atlantic Oscillation (NAO).  In this presentation we investigate the ENSO-NAO teleconnection in historical and RCP8.5 scenario CMIP5 simulations, and show a future strengthening of the teleconnection under RCP8.5.  The teleconnection strength is associated with increased tropical east Pacific rainfall variability.  Stratospheric and tropospheric teleconnection pathways are examined, with both pathways having stronger links in future.  The stratospheric pathway involves the Aleutian Low and the stratospheric polar vortex, with a downward influence on the NAO.  This pathway is clearest in the high-top models that better resolve the stratosphere.  The tropospheric pathway is driven by the Pacific subtropical jet strengthening and extending further into the Atlantic in future, generating increased baroclinicity in the Caribbean and influencing the Atlantic storm track.  Our results suggest increasing influence of tropical rainfall on extratropical circulation in future.