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The role of the Indonesian Throughflow on ENSO dynamics in a coupled climate model


Santoso, A and Cai, W and England, MH and Phipps, SJ, The role of the Indonesian Throughflow on ENSO dynamics in a coupled climate model, Journal of Climate, 24 pp. 585-601. ISSN 0894-8755 (2011) [Refereed Article]


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Copyright 2011 American Meteorological Society

DOI: doi:10.1175/2010JCLI3745.1


The effects of the Indonesian Throughflow (ITF) on ENSO dynamics are studied in a coupled climate model by comparing two simulations, one with an open ITF and the other with a closed ITF. Closing the ITF results in an El Nino–like climate state in the Pacific, which is characterized by weakened trade winds, a flatter equatorial thermocline, and weaker equatorial upwelling. A weakened South Equatorial Current allows the western Pacific warm pool to extend eastward, thereby reducing the zonal temperature gradient along the equator. The interdecadal component of the ENSO-like variability collapses, although the interannual variability is maintained. The core region of the ENSO SST anomalies becomes confined farther east. This results from Bjerknes feedback processes that are shifted eastward. This study conducts an analysis utilizing the Bjerknes coupled stability index as formulated by Jin et al. and finds that the relative importance of the thermocline feedback is enhanced in the closed ITF experiment. This indicates a more prominent ENSO thermocline mode, thus explaining the existence of more prevalent eastward-propagating anomalies. A weaker zonal advective feedback due to the reduced mean zonal temperature gradient contributes to the dominance of the thermocline mode. The strength of the thermocline feedback itself is maintained by enhanced coupling between the zonal wind stress and the east–west thermocline slope. However, an increased thermal damping by air–sea heat flux dominates the overall ENSO feedback process.

Item Details

Item Type:Refereed Article
Keywords:El Nino-Southern Oscillation
Research Division:Earth Sciences
Research Group:Climate change science
Research Field:Climatology
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Climate variability (excl. social impacts)
UTAS Author:Phipps, SJ (Dr Steven Phipps)
ID Code:104709
Year Published:2011
Web of Science® Times Cited:29
Deposited By:IMAS Research and Education Centre
Deposited On:2015-11-18
Last Modified:2017-10-30
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