Extratropical control of recent tropical Pacific decadal climate variability: a relay teleconnection

Abstract

Observations indicate that recent tropical Pacific decadal climate variability tends to be associated with the extratropical North Pacific through a relay teleconnection of a fast coupled ocean-atmosphere bridge and a slow oceanic tunnel. A coupled ocean-atmosphere model, forced by the observed decadal wind in the extratropical North Pacific, explicitly demonstrates that extratropical decadal sea surface temperature (SST) anomalies may propagate to the tropics through a coupled wind-evaporative-SST (WES) feedback. The WES feedback cannot only lead to a nearly synchronous change of tropical SST, but also force a delayed adjustment of the meridional overturning circulation in the upper ocean to further sustain the tropical SST change. The study further suggests that the extratropical–tropical teleconnection provides a positive feedback to sustain the decadal changes in both the tropical and extratropical North Pacific.