Extratropical control of tropical climate, the atmospheric bridge and oceanic tunnel

A coupled ocean‐atmosphere model study shows that the extratropical impact on tropical climate is as strong as the tropical impact on extratropical climate. A 2°C SST warming in the global extratropics increases equatorial ocean temperature by ∼1°C in the surface and subsurface. The surface temperature change is caused by the atmospheric bridge of the Hadley circulation (70%) and the oceanic tunnel of thermocline subduction (30%), while the subsurface temperature change is forced predominantly through the oceanic tunnel. Furthermore, the dominant influence on the equator comes from the southern hemisphere atmosphere and ocean.