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Southern Ocean Intrinsic and Forced Modes of Low Frequency


O'Kane, TJ and Matear, R and Chamberlain, MA and Risbey, JS and Sloyan, BM and Horenko, I, Southern Ocean Intrinsic and Forced Modes of Low Frequency, Proceedings of the 18th Australasian Fluid Mechanics Conference, AFMC 2012, 03-07 December, Launceston, Australia, pp. 1-4. ISBN 978-064658373-0 (2012) [Refereed Conference Paper]


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Copyright 2012 The Authors.

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A coupled Ocean-Sea ice General Circulation Model (OGCM) is used to identify a Southern Ocean southeast Pacific intrinsic mode of low frequency variability. This mode is co-located with a major region of Sub-Antarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) formation. Using CORE data a comprehensive suite of experiments were carried out to elucidate excitation and amplification mechanisms of this intrinsic mode by low frequency forcing (ENSO, SAM) and stochastic forcing due to high frequency winds. Subsurface thermocline anomalies were found to teleconnect the Pacific and Atlantic regions of the Antarctic Circumpolar Current (ACC). The Pacific region of the ACC is characterised by intrinsic baroclinic disturbances that respond to both SAM and ENSO, while the Atlantic sector of the ACC is sensitive to higher frequency winds that act to amplify thermocline anomalies propagating downstream from the Pacific resonant with eastward travelling Rossby waves. This simulation study identifies plausible mechanisms that determine the predictability of the Southern Ocean climate on multi-decadal timescales.

Item Details

Item Type:Refereed Conference Paper
Keywords:oceanography, climatology, OGCM, Southern Ocean
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical oceanography
Objective Division:Environmental Management
Objective Group:Management of Antarctic and Southern Ocean environments
Objective Field:Antarctic and Southern Ocean oceanic processes
UTAS Author:O'Kane, TJ (Dr Terry O'Kane)
UTAS Author:Matear, R (Dr Richard Matear)
UTAS Author:Risbey, JS (Dr James Risbey)
UTAS Author:Sloyan, BM (Dr Bernadette Sloyan)
ID Code:119774
Year Published:2012
Deposited By:Oceans and Cryosphere
Deposited On:2017-08-04
Last Modified:2017-10-13
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