Mechanisms of the meridional heat transport in the Southern Ocean

Denis L. Volkov, Lee Lueng Fu, Tong Lee

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

The Southern Ocean (SO) transports heat towards Antarctica and plays an important role in determining the heat budget of the Antarctic climate system. A global ocean data synthesis product at eddy-permitting resolution from the Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2) project is used to estimate the meridional heat transport (MHT) in the SO and to analyze its mechanisms. Despite the intense eddy activity, we demonstrate that most of the poleward MHT in the SO is due to the time-mean fields of the meridional velocity, V, and potential temperature, θ. This is because the mean circulation in the SO is not strictly zonal. The Antarctic Circumpolar Current carries warm waters from the region south of the Agulhas Retroflection to the lower latitudes of the Drake Passage and the Malvinas Current carries cold waters northward along the Argentinian shelf. Correlations between the time-varying fields of V and θ (defined as transient processes) significantly contribute to the horizontal-gyre heat transport, but not the overturning heat transport. In the highly energetic regions of the Agulhas Retroflection and the Brazil-Malvinas Confluence the contribution of the horizontal transient processes to the total MHT exceeds the contribution of the mean horizontal flow. We show that the southward total MHT is mainly maintained by the meridional excursion of the mean geostrophic horizontal shear flow (i.e., deviation from the zonal average) associated with the Antarctic Circumpolar Current that balances the equatorward MHT due to the Ekman transport and provides a net poleward MHT in the SO. The Indian sector of the SO serves as the main pathway for the poleward MHT.

Original languageEnglish (US)
Pages (from-to)791-801
Number of pages11
JournalOcean Dynamics
Volume60
Issue number4
DOIs
StatePublished - Aug 2010
Externally publishedYes

Keywords

  • Antarctic circumpolar current
  • Eddy-induced heat transport
  • Horizontal gyre transport
  • Meridional heat transport
  • Meridional overturning circulation
  • Southern Ocean

ASJC Scopus subject areas

  • Oceanography

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