Highest-ever winter water temperatures recorded

August 6, 2009
Highest-ever winter water temperatures recorded
NOAA polar orbiting satellites obtain the data generating sea surface temperature images. This is a composite 15-day image showing the extension of the Leeuwin Current around Tasmania. Photo by: CSIRO

(PhysOrg.com) -- Tasmania’s east coast is recording its highest-ever winter water temperatures of more than 13ºC - up to 1.5ºC above normal - due to a strengthening of an ocean current originating north of Australia.

Satellites have given oceanographers an insight into a remarkable phenomenon - a significant extension of the Leeuwin Current curling around the southern tip of Tasmania and reaching as far north as St Helens.

Remote sensing specialists at CSIRO's Wealth from Oceans Flagship have been observing the current in recent days using satellite data, and ocean measurements made near Maria Island on Tasmania’s east coast.

CSIRO oceanographers Katy Hill, David Griffin and George Cresswell study ocean behaviour in the Australian region. Dr Cresswell says that scientists use ocean observations from satellite, ocean instruments and research vessels - such as the Marine National Facility, RV Southern Surveyor - to track the currents but there are also other indicators such as tropical species reaching Tasmania.

“It’s important for us to monitor these changes in the ocean, as they can have consequences for marine ecosystems, fisheries, aquaculture, coastal communities and more,” Dr Cresswell says.

The Leeuwin Current forms north of Australia and flows right around the western half of the country, meeting its better known cousin, the East Australian Current (EAC), at Tasmania. The exact location of this meeting point varies both seasonally and from year-to-year, depending on how strongly each current is flowing.

Oceanographers believe the EAC has gradually been getting stronger, and the Leeuwin Current weaker. Changes in the EAC are among the most significant in the global ocean, with a continuous record of monthly measurements one of Australian oceanography’s most valuable indicators for climate and .

Observations of temperature, salinity and nutrients have been collected monthly just east of Maria Island since 1944, showing how the influence of both the EAC and Leeuwin Current systems varies in Tasmanian waters. As part of the Integrated Marine Observing System (IMOS), a National Reference Station mooring has been deployed at the same site, and data is now available online every 10 minutes. Monthly samples are taken by boat to measure nutrients, phytoplankton, and zooplankton (biomass and species composition).

Satellite images indicate the surface water temperature over the continental shelf current is around 13 degrees, a degree or two warmer than at this time in recent years. The EAC has been a research focus for Katy Hill since 2005 as part of her PhD in the Quantitiative Marine Science program - a joint initiative of CSIRO and the University of Tasmania.

The St Helens-based Chief Executive of the Tasmanian Rock Lobster Association, Rodney Treloggen, said he was not aware of any reports of Indian Ocean species but he said fishers were concerned at what he described as a “bad year” for the industry in the south-east and east coast.

"We know the warmer waters have an impact but we're not sure how much," Mr Treloggen said.

Provided by CSIRO (news : web)

Explore further: Cold-water eddy 'monsters' mighty current off Sydney

Related Stories

Fish growth changes enhanced by climate change

April 27, 2007

Changes in growth rates in some coastal and long-lived deep-ocean fish species in the south west Pacific are consistent with shifts in wind systems and water temperatures, according to new Australian research published in ...

'Ocean glider' home after two-month voyage

April 16, 2009

Scientists are celebrating the first successful deployment and retrieval in Australia of a remotely controlled, deep ocean-going robotic submarine destined to play a central role in measuring changes in two of Australia's ...

Recommended for you

Ice sheets may be more resilient than thought

September 3, 2015

Sea level rise poses one of the biggest threats to human systems in a globally warming world, potentially causing trillions of dollars' worth of damages to flooded cities around the world. As surface temperatures rise, ice ...

Clues from ancient Maya reveal lasting impact on environment

September 3, 2015

Evidence from the tropical lowlands of Central America reveals how Maya activity more than 2,000 years ago not only contributed to the decline of their environment but continues to influence today's environmental conditions, ...

Climate ups odds of 'grey swan' superstorms

August 31, 2015

Climate change will boost the odds up to 14-fold for extremely rare, hard-to-predict tropical cyclones for parts of Australia, the United States and Dubai by 2100, researchers said Monday.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.