Research
Research Voyage - March 2006
Instrument to Take the Southern Ocean's pulse
By Stuart French
A major collaborative project to study the Southern Ocean's influence
on climate will advance further this October [2006] with the deployment
of a specially-engineered ocean measuring instrument from the Antarctic
resupply ship Aurora Australis.
Led by Dr Tom Trull, a scientist at the Antarctic Climate & Ecosystems
Cooperative Research Centre and CSIRO Marine and Atmospheric Research,
the project is monitoring physical, biological and chemical interactions
in the sub-Antarctic zone of the Southern Ocean, south of Australia.
"We want to detect how the ocean absorbs carbon dioxide from
the atmosphere and in this environment, the instrument and its
seafloor mooring need to withstand massive physical pressures from
storms and ocean currents," says project scientist, Dr Bronte
Tilbrook.
"The mooring is designed to provide year-round data we need
to determine controls on the growth of phytoplankton, and how carbon
dioxide is absorbed by the ocean and transported to the deep sea," says
Dr Tilbrook.
"The Southern Ocean at these latitudes is one of the most
important regions on earth for absorbing carbon dioxide," he
says.
As part of the PULSE project, the instrument will float at the
surface but be anchored to the sea floor at about 4200 metres depth.
It will be the first surface mooring in the region and will measure
changes in the Southern Ocean at 47°S during 2006 and 2007.
Climate scientists will use the data to simulate the way the Southern
Ocean will respond to increasing levels of carbon dioxide in the
atmosphere.
Dr Tilbrook says one of the greatest challenges of the project
has been engineering the PULSE float to prevent it from being torn
from its mooring in the inhospitable Southern Ocean, where seas
reach up to 20 metres in height.
"The engineering and mooring groups had to overcome a large
number of problems and have done a fantastic job with the whole
package," he says.
The complete mooring structure weighs about five tonnes. It is
anchored to the sea floor by another tonne of iron train wheels.
To dampen wave motion at the surface, the mooring specialists at
CMAR have used an enormous rubber shock cord, similar in effect
to a bungie.
The instrument will be retrieved and re-deployed during a voyage
by the National Marine Research Facility vessel, Southern
Surveyor,
in April, 2007 says Dr Tilbrook.
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Last updated
2/11/06
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