University Of Tasmania

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Reassessing conceptual models of ENSO

journal contribution
posted on 2023-05-18, 12:25 authored by Felicity McCormack, Brown, JN, Wittenberg, AT, Neil HolbrookNeil Holbrook
The complex nature of El Nino - Southern Oscillation (ENSO) is often simplified through the use of conceptual models, each of which offers a different perspective on the ocean-atmosphere feedbacks underpinning the ENSO cycle. One theory, the unified oscillator, combines a variety of conceptual frameworks in the form of a coupled system of delay differential equations. The system produces a self-sustained oscillation on interannual timescales. While the unified oscillator is assumed to provide a more complete conceptual framework of ENSO behaviors than the models it incorporates, its formulation and performance have not been systematically assessed. This paper investigates the accuracy of the unified oscillator through its ability to replicate the ENSO cycle modeled by flux-forced output from the Australian Community Climate and Earth System Simulator Ocean Model (ACCESS-OM). The anomalous sea surface temperature equation reproduces the main features of the corresponding tendency modeled by ACCESS-OM reasonably well. However, the remaining equations - for the thermocline depth anomaly and zonal wind stress anomalies - are unable to accurately replicate the corresponding tendencies in ACCESS-OM. Modifications to the unified oscillator, including a diagnostic form of the zonal wind stress anomaly equations, improve its ability to emulate simulated ENSO tendencies. Despite these improvements, the unified oscillator model is less adept than the delayed oscillator model it incorporates in capturing ENSO behavior in ACCESS-OM, bringing into question its usefulness as a unifying ENSO framework.


Publication title

Journal of Climate










Institute for Marine and Antarctic Studies


Amer Meteorological Soc

Place of publication

45 Beacon St, Boston, USA, Ma, 02108-3693

Rights statement

Copyright 2015 American Meteorological Society

Repository Status

  • Restricted

Socio-economic Objectives

Climate variability (excl. social impacts)

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