The role of the Indonesian Throughflow in the latest ENSO events

The moored current meter observations in the Maluku Channel of the Indonesian seas have shown significant northeastward current anomalies during the summer 2016 through early 2017, forced by downwelling Kelvin waves propagating from the equatorial Indian Ocean through the Makassar Strait, weakening the ITF transport and deepening the western Pacific thermocline. The anomalous ITF transport halted the onset of an otherwise strong 2016 La Niña, and is responsible for triggering a phase transition to an accelerated warming trend in the Pacific cold tongue sea surface temperature anomalies and in global mean surface temperature since 2014. The Kelvin waves were generated by the strong negative Indian Ocean Dipole in 2016, which is suggested to be induced by significant heat build-up in the tropical Indian Ocean associated with the 2015/2016 strong El Niño and enhanced by the decadal sea level rise during the recent global warming hiatus. The results suggest the importance of the ITF variability in the interannual-to-decadal climate variability in the Indo-Pacific ocean and globally.