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Storm tracks in the Southern Hemisphere subtropical oceans

Citation

O'Kane, TJ and Matear, RJ and Chamberlain, MA and Oliver, ECJ and Holbrook, NJ, Storm tracks in the Southern Hemisphere subtropical oceans, Journal of Geophysical Research: Oceans, 119, (9) pp. 6078-6100. ISSN 2169-9275 (2014) [Refereed Article]


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Copyright Statement

Copyright 2014 American Geophysical Union

DOI: doi:10.1002/2014JC009990

Abstract

Ocean storm tracks have previously been associated with the midlatitude western boundary currents (WBCs) and the Antarctic Circumpolar Current (ACC). Here we identify and examine large-scale baroclinically unstable waves occurring within waveguides associated with potential density gradients in the subtropical regions of the Southern Hemisphere (SH) oceans where the trade winds and westerlies meet and at depths associated with mode water formation. In contrast to the Northern Hemisphere subtropics, the SH pathways are more extensive allowing large-scale coherent disturbances to communicate information westward from the midlatitudes to the subtropics (South Pacific Ocean) and from the subtropics to the tropics (Indian Ocean). Particular consideration is given to the subtropical South Pacific Ocean as this is a region where resonant interactions between large-scale Rossby waves and significant topographic features have been reported to occur. Using an ocean general circulation model and a simple potential energy transfer diagnostic, we identify the relevant nonlinearly modified structures comparing their propagation characteristics to planetary Rossby waves calculated using a shallow water model. Although at first appearance baroclinic disturbances resemble planetary Rossby waves, we show they are inherently nonlinear, multiscale and are amplified where topography occurs. The location of the disturbances coincides with regions of high variability in sea surface height observed in satellite altimetry and their speeds closely match the large-scale coherent westward propagating structures described in the observational literature. Our study provides evidence that, in addition to the midlatitude WBCs and the ACC, significant ocean storm tracks are also manifest in the SH subtropics.

Item Details

Item Type:Refereed Article
Keywords:southern ocean, storm tracks, predictability
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical Oceanography
Objective Division:Environment
Objective Group:Climate and Climate Change
Objective Field:Climate Variability (excl. Social Impacts)
Author:Oliver, ECJ (Dr Eric Oliver)
Author:Holbrook, NJ (Professor Neil Holbrook)
ID Code:97089
Year Published:2014
Web of Science® Times Cited:7
Deposited By:IMAS Research and Education Centre
Deposited On:2014-12-02
Last Modified:2017-11-30
Downloads:8 View Download Statistics

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