Contribution of tropical instability waves to ENSO irregularity

What is it about?

The El Nino - Southern Oscillation (ENSO) is the largest source of year-to-year climate variability on the Planet, impacting extreme weather around the globe. Each El Nino and La Nina event has different characteristics, with differing remote impacts. One major source for this ENSO irregularity is stochastic noise from synoptic-scale atmospheric weather, which impacts on the skill of ENSO predictions. However, the tropical ocean also contains small-scale random eddy variability that could contribute to the noise forcing of ENSO. In this study, we use a hybrid coupled model of the tropical Pacific to show that ocean-sourced noise can drive significant variability amongst ENSO events, with implications for ENSO predictability and its representation in low-resolution coupled models that do not resolve small-scale oceanic features.

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