20 September 2007 - Lasers
from helicopters and space satellites are
being used in Antarctica, for the first
time, to determine whether sea ice in the
Southern Ocean is changing in response to
climate change.
Sea ice plays an essential role in regulating
global climate as well as supporting the
Southern Ocean ecosystem, and there are
concerns that Antarctic sea ice may be getting
thinner.
Setting up a sea ice station.Photo: ACE
CRC A team of international researchers,
led by the Antarctic Climate and Ecosystems
Cooperative Research Centre (ACE CRC), is
on a six-week expedition in the Southern
Ocean aboard the Antarctic research ship
Aurora Australis, which left Hobart earlier
this month.
Two helicopters equipped with laser altimeters
are taking measurements of sea ice thickness.
These will be tested against satellite-based
measurements, taken as part of a separate
US National Aeronautics and Space Administration
(NASA) ICESat science project.
The ultimate aim of the helicopter altimetry,
combined with surface measurements taken
by scientists on the ice, is to help validate
measurements from satellites. These can
then be used to estimate Antarctic sea ice
thickness over large areas.
Voyage leader Dr Tony Worby said that to
date relatively few measurements of Antarctic
sea ice thickness have been made, meaning
that any variations related to recent climate
change may have been going unnoticed.
"While laser altimetry has been used
in the Arctic, it is the first time it has
been tested in the Antarctic.
"The lasers provide a direct estimate
of how much ice and snow is above the water
level and, combined with the surface measurements,
the data will help us validate and improve
satellite measurements of Antarctic sea
ice thickness over large areas.
"We are collecting excellent data
which we expect will considerably improve
our knowledge of sea ice in this region
of Antarctica, and it should give us the
tools to monitor whether Antarctic sea ice
is changing over coming years," Dr
Worby said.
The Sea Ice Physics and Ecosystems eXperiment
(SIPEX) research is an international project
jointly organised by the ACE CRC and the
Australian Antarctic Division. It involves
45 researchers from ten different countries
and is part of a larger International Polar
Year (IPY) project investigating sea ice
in the Antarctic.
SIPEX is also investigating the interactions
between sea ice structure, sea ice biology
and the ocean food web. The expedition will
return to Hobart on 17 October.
Voyage website: www.acecrc.sipex.aq
Patti Lucas, Australian Antarctic Division
