Enhancing the ENSO Predictability beyond the Spring Barrier.

El Niño-Southern Oscillation (ENSO) is the dominant interseasonal-interannual variability in the tropical Pacific and substantial efforts have been dedicated to predicting its occurrence and variability because of its extensive global impacts. However, ENSO predictability has been reduced in the 21st century, and the impact of extratropical atmosphere on the tropics has intensified during the past 2 decades, making the ENSO more complicated and harder to predict. Here, by combining tropical preconditions/ocean-atmosphere interaction with extratropical precursors, we provide a novel approach to noticeably increase the ENSO prediction skill beyond the spring predictability barrier. The success of increasing the prediction skill results mainly from the longer lead-time of the extratropical-tropical ocean-to-atmosphere interaction process, especially for the first 2 decades of the 21st century.