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Deepening of Southern Ocean gateway leads to abrupt onset of a deep-reaching meridional overturning circulation
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  • Qianjiang Bryant Xing,
  • Andreas Klocker,
  • David R Munday,
  • Joanne M Whittaker
Qianjiang Bryant Xing
University of Tasmania

Corresponding Author:[email protected]

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Andreas Klocker
NORCE Norwegian Research Centre
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David R Munday
British Antarctic Survey
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Joanne M Whittaker
University of Tasmania
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During the Eocene-Oligocene transition, the meridional overturning circulation underwent large changes, associated with the geological evolution of Southern Ocean gateways. These are crucial for the Cenozoic climate transition from Greenhouse to Icehouse, but their dynamics still remain elusive. We demonstrate, using an idealised eddying ocean model, that the opening of a gateway leads to an abrupt onset of a vigorous, deep-reaching, meridional overturning circulation. This meridional overturning circulation has a maximum transport for a shallow gateway, and decreases with further deepening of the gateway. This abrupt change in the meridional overturning circulation can be explained through the ability with which standing meanders -- turbulent features located downstream of the gateway -- can induce deep vertical heat transport at high latitudes where bottom waters are produced. Our results demonstrate the crucial role of turbulent processes, associated with tectonic evolution, in setting the strength of the global ocean's deep-reaching meridional overturning circulation.
07 Feb 2023Submitted to ESS Open Archive
09 Feb 2023Published in ESS Open Archive