Low frequency variability in an coupled ocean-sea ice general circulation model of the Southern Ocean

A coupled ocean-sea ice general circulation model is used to identify a Southern Ocean southeast Pacific intrinsic mode of low frequency variability and its response to inter-annual atmospheric forcing. Using forcing data from the co-ordinated ocean-ice reference experiment, a comprehensive suite of...

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Bibliographic Details
Published in:ANZIAM Journal
Main Authors: O'Kane, TJ, Matear, R, Chamberlain, MA, Risby, JS, Horenko, I, Sloyan, BM
Format: Article in Journal/Newspaper
Language:English
Published: Australian Mathematics Publ Assoc Inc 2012
Subjects:
Earth Sciences
Oceanography
Physical Oceanography
Antarctic
Southern Ocean
The Antarctic
Pacific
Antarc*
Sea ice
Online Access:https://doi.org/10.21914/anziamj.v54i0.6178
http://ecite.utas.edu.au/118949
Description
Summary:A coupled ocean-sea ice general circulation model is used to identify a Southern Ocean southeast Pacific intrinsic mode of low frequency variability and its response to inter-annual atmospheric forcing. Using forcing data from the co-ordinated ocean-ice reference experiment, a comprehensive suite of experiments elucidated excitation and amplification mechanisms of this intrinsic mode by low frequency forcing and stochastic forcing due to high frequency winds. Subsurface thermocline anomalies are found to teleconnect the Pacific and Atlantic regions of the Antarctic circumpolar current (ACC). It is found that the Pacific region of the ACC is characterised by intrinsic baroclinic disturbances that respond to both zonal and latitudinal wind variations, while the Atlantic sector of the ACC is sensitive to higher frequency synoptic 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.

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