Sea ice under scrutiny from space

Five people working on sea ice to set up equipment.
Setting up a sea ice station. (Photo: ACE CRC)

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.

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