Ocean Currents
Summer and Winter Currents around Tasmania
Source: CSIRO Australia
Tasmania is affected by a complex array of ocean currents that vary between summer and winter. The most significant of these currents are the Antarctic Circumpolar Current, which originates in the Southern Ocean, and the East Australian Current, which flows south through the Tasman Sea.
The Antarctic Circumpolar Current is a region of upwelling deep water, and so is very rich in nutrients which support profuse marine life. Where the Antarctic Circumpolar Current converges with more northerly currents is an area of downwelling, known as the Subtropical Convergence (40–45°S), and along its southern margin is the Antarctic Convergence (50–55°S). Part of the Antarctic Circumpolar Current is deflected up the west coast of Tasmania to form the Flinders Current. The Leeuwin Current flows around Cape Leeuwin, Western Australia, and across the Great Australian Bight. Its continuation forms the southward-flowing Zeehan Current, commonly found in winter.
The eastern seaboard is affected by the East Australian Current. It often generates warm-core eddies, or circular waterflows, up to several hundred kilometres across. These eddies drift south and can be found off the central east coast of the State. In winter, Bass Strait occasionally receives waters from the Zeehan Current. This combines with the Flinders Current to form the eastward-flowing Bass Strait Cascade. During summer East Australian Current water flows through Bass Strait and onto the shelf of the Great Australian Bight, where it combines with the Flinders Current.
The position of the East Australian Current varies significantly over periods corresponding roughly with the El Nino – Southern Oscillation cycle, and this controls the latitude of the Subtropical Convergence. These variations affect the biological communities off Tasmania’s coast through changes to water temperatures, nutrient availability and so on.
Further Information
Contact: Coastal and Marine Branch
Coastal and Marine Branch
6th Floor, Lands Building, 134 Macquarie Street
GPO Box 1751
Hobart TAS 7001
Phone: 03 6233 3963
Fax: 03 6233 6800
Email: Coastal.Enquiries@environment.tas.gov.au
