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

Authors

  • Terence John O'Kane CSIRO Marine and Atmospheric Research
  • Richard Matear CSIRO Marine and Atmospheric Research
  • Matthew Chamberlain CSIRO Marine and Atmospheric Research
  • James Risbey CSIRO Marine and Atmospheric Research
  • Illia Horenko Universita della Svizzera Italiana, Lugano
  • Bernadette Sloyan CSIRO Marine and Atmospheric Research

DOI:

https://doi.org/10.21914/anziamj.v54i0.6178

Keywords:

intrinsic, forced and low frequency ocean modes

Abstract

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. References
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Author Biographies

Terence John O'Kane, CSIRO Marine and Atmospheric Research

Senior Research Scientist ARC Future Fellow

Richard Matear, CSIRO Marine and Atmospheric Research

Senior Research Scientist

Matthew Chamberlain, CSIRO Marine and Atmospheric Research

Project Scientist

James Risbey, CSIRO Marine and Atmospheric Research

Senior Research scientist

Illia Horenko, Universita della Svizzera Italiana, Lugano

Professor

Bernadette Sloyan, CSIRO Marine and Atmospheric Research

Senior Research scientist

Published

2013-05-27

Issue

Section

Proceedings Computational Techniques and Applications Conference