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Reassessing conceptual models of ENSO


Graham, FS and Brown, JN and Wittenberg, AT and Holbrook, NJ, Reassessing conceptual models of ENSO, Journal of Climate, 28, (23) pp. 9121-9142. ISSN 0894-8755 (2015) [Refereed Article]

Copyright Statement

Copyright 2015 American Meteorological Society

DOI: doi:10.1175/JCLI-D-14-00812.1


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.

Item Details

Item Type:Refereed Article
Keywords:ENSO, conceptual model, El Nino
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical oceanography
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Climate variability (excl. social impacts)
UTAS Author:Graham, FS (Dr Felicity McCormack)
UTAS Author:Holbrook, NJ (Professor Neil Holbrook)
ID Code:102457
Year Published:2015
Web of Science® Times Cited:7
Deposited By:IMAS Research and Education Centre
Deposited On:2015-08-21
Last Modified:2017-11-01

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