Water mass formation, upwelling and fronts in the Great Australian Bight

Michael Herzfeld¹, Michael Schodlok² and Matthias Tomczak

Flinders Institute for Atmospheric and Marine Sciences, the Flinders University of South Australia, GPO Box 2100, Adelaide SA 5001, Australia

¹ now at Centre for Water Research, the University of Western Australia, Nedlands WA 6907, Australia

² now at Alfred-Wegener-Institut für Polar- und Meeresforschung, Am Handelshafen 12, D-27570 Bremerhaven, Germany

email:

A poster presented at the TOS and IOC Meeting on Coastal and Marginal Seas at the UNESCO Headquarters in Paris, France, during 1-4 June 1998

TOS: The Oceanography Society
IOC: International Oceanographic Commission
UNESCO: United Nations Educational, Scientific and Cultural Organisation

Abstract

The Great Australian Bight and adjacent waters are described through observations and modeling as a region of water mass formation from enhanced air-sea exchange in the coastal zone. The warm water formed in the summer months spreads offshore and eastward. It is shown that advection of warm water from the Leeuwin Current, which was previously believed to be responsible for the observed warming south of Australia, comes into play only towards the end of summer.

The circulation is dominated by a wind driven anti-cyclonic gyre with strong upwelling in the east. The upwelling is not driven by the coastal wind but is a result of conservation of potential vorticity over a sloping bottom, which produces a shift of the gyre centre relative to the centre of the wind system, resulting in upwelling through the bottom boundary layer.

The southern limit of this circulation is the Subtropical Front, which south of Australia is found to bend strongly northward, weakening at the same time. Density compensation of temperature and salinity along the front is nearly complete, and the front is associated with very little transport.

This page was created on 21/5/98

contact address: