Understanding Lead Times of Warm Water Volumes to ENSO Sea Surface Temperature Anomalies
Predicting El Niño-Southern Oscillation (ENSO) events in advance has profound socio-economic benefits because of ENSO’s impacts on global weather and climate. The basin-wide equatorial Pacific heat content (also known as warm water volume, WWV) and western Pacific WWV (WWVw) are well-known predictors of ENSO events several seasons ahead. In this study, we present an analytical expression of WWV and WWVw lead times to ENSO sea surface temperature (SST) anomalies. The analytical solution can explain the observed decadal changes in WWV lead times. We demonstrate that the recent shortened WWV lead time observed after the year 2000 can be largely explained by a decrease in the inherent ENSO periodicity, and second by an increase in the air-sea coupling strength. The latter is associated with an ENSO SST spatial pattern change with more frequent occurrences of Central Pacific El Niño events in recent decades.
Sep 17, 2021