30 November 2016

Initialized Decadal Prediction for Transition to Positive Phase of the Interdecadal Pacific Oscillation

Science

The negative phase of the Interdecadal Pacific Oscillation (IPO), a dominant mode of multi-decadal variability of sea surface temperatures (SSTs) in the tropical Pacific, contributed to the reduced rate of global surface temperature warming in the early 2000s.  A proposed mechanism for IPO multidecadal variability indicates that the build-up of upper ocean heat content in the off-equatorial western tropical Pacific in the 1980s and 1990s could provide conditions for an El Niño/Southern Oscillation (ENSO) event to trigger a transition of tropical Pacific SSTs to the opposite IPO phase.  

Impact

A decadal prediction initialized in 2013 shows that the Niño3.4 SSTs have qualitatively tracked the observations through 2015 with a small El Niño in 2014, and a larger El Niño event in 2015.  

Summary

The year 3-7 average prediction (2015-2020) from the 2013 initial state shows a transition to the positive phase of the IPO from the previous negative phase, and a resumption of larger rates of global warming consistent with a positive IPO phase.

Contact
Gerald Meehl
National Center for Atmospheric Research (NCAR)