Abstract

Not all El Niño-Southern Oscillation (ENSO) events are the same. ENSO global impacts can differ substantially depending on whether the associated sea surface temperature (SST) anomalies are larger in the Eastern Pacific (EP) or Central Pacific (CP), making the predictability of such differences of very high societal relevance. In this presentation, we first examine the ability of SST-based tropical and extra-tropical “precursors” to trigger different types of ENSO events. We then objectively identify the optimal two-season precursors of EP and CP-type events in a Linear Inverse Modeling (LIM) framework, using SST and thermocline depth data over 1958-2007. The results highlight the importance of the initial subsurface ocean conditions for the development of different event types. The results are finally examined in the context of the evolution of SST and subsurface ocean conditions over recent decades.