Contributions of tropical-extratropical oceans to the prediction skill of ENSO after 2000

Abstract

The skill of most ENSO prediction models has declined significantly since 2000. This decline may be due to a weakening of the correlation between tropical predictors and ENSO. Moreover, the effects of extratropical ocean variability on ENSO have increased during this period. To improve ENSO predictability, the authors investigate the influence of the extratropical Atlantic and Pacific oceans on ENSO during the pre-2000 and post-2000 periods, and find that the influence of the northern tropical Atlantic sea surface temperature (NTA SST) on ENSO has significantly increased since 2000. Furthermore, there is a much earlier and stronger correlation between NTA SST and ENSO over the central-eastern Pacific during June-July-August in the post-2000 period compared with the pre-2000 period. The extratropical Pacific SST predictors for ENSO retain an approximate 10-month lead time after 2000. The authors use SST signals in the extratropical Atlantic and Pacific to predict ENSO using a statistical prediction model. This results in a significant improvement in ENSO prediction skill and an obvious decrease in the spring predictability barrier phenomenon of ENSO. These results indicate that extratropical Atlantic and Pacific SSTs can make substantial contributions to ENSO prediction, and can be used to enhance ENSO predictability after 2000.