Assoc Prof John Middleton

Circulation along Australia's Southern Shelves

The circulation along Australia's southern shelves is affected by the Leeuwin Current in the west and equatorward Sverdrup transport in the south. The latter leads to the Flinders Current, a "small" sister current to the main western boundary currents of the world. During winter and summer, the winds near the shelf reverse leading to coastal currents that flow to the east (winter) and west (summer). Very strong downwelling (to depths of 150 m) dominates during winter, while during summer, episodic upwelling occurs between the Eyre Peninsula and Portland.  Downwelling is shown to exist all year around at the shelf break of the western Bight and is a likely explanation of the low primary productivity found there. During El Nino summers, the raised thermocline in the western Pacific, propagates along the West Australian shelf slope and into the Bight. This leads to cold nutrient rich water that is closer to the surface and possibly enhanced primary productivity. Local atmospheric heating and cooling is also important to the circulation and flushing of the Gulfs. Research into this fascinating region continues and some results are summarised below.

Papers:

• Wind forced Downwelling: an idealised study

• Wind forced upwelling: the role of the surface mixed layer

• A tidal model for the region

• Slope current set-up near a strait

• The Flinders Current: a northern boundary current

• The Mean Wintertime Circulation along Australia's Southern Shelves

• The Mean Summertime Circulation along Australia's Southern Shelves

• The 1998-1999 Weather-band Variability and Upwelling off the South Australian Shelf

• Middleton, J. F. and M. Cirano, 2005: The wintertime circulation along the south-eastern Australian shelf: a numerical study. J. Geophys. Res., 110, C12012, doi:10.1029/2004JC002855.

• McClatchie, S., J.F. Middleton, and T. Ward, 2006: Water mass analysis and alongshore variation in upwelling intensity in the eastern Great Australian Bight. J. Geophys. Res., 111, C08007, doi:10.1029/2004JC002699

• Middleton J. F., C. Arthur, P. van Ruth, T. Ward, J. McClean, M. Maltrud, P. Gill, S. Middleton, 2007: El Nino effects and upwelling off South Australia. J Phys. Oceanogr, accepted.

• Middleton, J. F., and J.T Bye, 2007: The Physical Oceanography of Australia’s Southern Shelves: a review. Progress in Oceanography, accepted.

Links:

• South-East Fishery Movies (David Griffin)

< Back to Dr John Middleton's homepage

Top of page