An eastern boundary current pathway from the Southern Ocean to the tropical Indian Ocean — Australian Meteorological and Oceanographic Society
  1. Schedule
  2. 02(i). New insights into Indian Ocean dynamics, variability, and change
  3. An eastern boundary current pathway from the Southern Ocean to the tropical Indian Ocean

An eastern boundary current pathway from the Southern Ocean to the tropical Indian Ocean (#35)

Helen E Phillips 1 , Qi Zheng 1 , Nathan L Bindoff 1 , Earl R Duran 1 2
  1. University of Tasmania, Battery Point, TAS, Australia
  2. Climate Change Research Centre, University of NSW, Sydney, NSW, Australia

The Leeuwin Undercurrent has long been known to carry Subantarctic Mode Water and Antarctic Intermediate Water northward beneath the poleward flowing Leeuwin Current. The velocity structure and transport of the undercurrent have recently been described from an observational climatology and global ocean model. However, the current’s watermass properties and their variation along the coast of Australia are still unclear. In this study we trace the Leeuwin Undercurrent, mapping its watermass properties, from its source near Cape Leeuwin to its separation from the coast near Northwest Cape. Furthermore, we trace the outflow pathway of Leeuwin Undercurrent waters as they leave the coast near 24S and flow westward into the interior of the Indian Ocean, at least as far as 90E. We find a clear pathway along which Subantarctic Mode Water and Antarctic Intermediate Water travel more than 3000 km with little modification. This suggests that changes in the Southern Ocean, such as warming and thickening of Subantarctic Mode Water, could relatively quickly be communicated to the tropical Indian Ocean, one of the fastest warming regions in the world.

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