Early spring in the Antarctic: Scientists investigate sea ice

Expeditioners undertaking ice coring, with icebreaker ship in background
Ice coring (Photo: Andrew Cianchi)
Sea ice algaeVarious phytoplanktonAn antarctic krill

30 August 2007

An earlier than usual foray into far southern waters will help scientists understand the connection between Antarctic sea ice and the ecosystems that depend on it for survival.

The voyage, to depart Hobart on September 4, is Australia's first in around 10 years to head into the Southern Ocean while the sea ice remains in place before the summer thaw.

The Sea Ice Physics and Ecosystem eXperiment (SIPEX*) voyage, jointly organised by the Antarctic Climate & Ecosystems Cooperative Research Centre (Antarctic CRC) and the Australian Antarctic Division, will sail from Hobart at the beginning of September 2007.

Eighty-six scientists from eight nations will use a suite of cutting-edge technologies to study processes on the sea ice surface, as well as within and under the ice in the region east of Australia's Casey Station.

The six-week voyage will examine interactions between sea ice structure, sea ice biology and the ocean food web.

Around 19 million square kilometres of sea ice forms around Antarctica every winter, covering an area of ocean almost three times the size of Australia. Most of it melts away over summer. The annual formation and melting of sea ice plays an important role in global ocean and climate processes as well as the winter survival of some species in the Southern Ocean ecosystem.

'Ice thickness is one of the big uncertainties about sea ice dynamics,' said voyage leader Dr Tony Worby. 'For the last 30 years or so, satellites have allowed us to measure the extent of sea ice over the ocean, but current remote sensing techniques are not effective at estimating the thickness of the ice or the snow that accumulates on it.'

The study will employ two new sophisticated airborne systems that will allow researchers to calculate the thickness of both the ice and its snow cover.

'This will be the first time that helicopter laser altimetry and snow radar have been used over Antarctic sea ice,' Dr Worby said. 'The data we collect will help validate information received from new satellite sensors that we hope will be useful for measuring sea ice thickness in the future.'

Sea ice also serves as a resting platform for marine mammals and birds, and provides a habitat for various groups of organisms such as bacteria and algae. These algal sea ice communities provide an important food source for Antarctic krill and other key species during winter and early spring.

'Longer daylight hours and melting snow and ice during early spring cause a rapid increase in biological activity in and under the ice,' notes biology team leader Dr Klaus Meiners. 'This makes it an ideal time to study these processes.'

The biology research team will send a Remotely Operated Vehicle (ROV) with optical sensors under the sea ice to measure the amount of algae within the ice and attached to the underside of the ice. Another sensor on the ROV will measure ice thickness. A specially-designed trawl net will be used to sample the environment directly under the ice and provide live krill that can be used for experiments in the ship's laboratories.

The sampling program will be complemented by an extensive sea ice coring and drilling program that will provide more data on both the physical and biological properties of the ice. Scientists will spend long hours measuring snow and ice density and thickness on drifting ice floes, as well as conducting experiments in special freezer laboratories on the ship.

The Antarctic CRC is creating a special website for the voyage that will include profiles of the scientists and their research, daily updates from the ship, education resources and a chance for readers to ask questions of the researchers. Two Tasmanian school teachers will also be on board adding their expertise to the development of the website materials. The website will be available at http://www.acecrc.sipex.aq.

*SIPEX is also part of a larger International Polar Year (IPY) research project. IPY runs from March 2007 to March 2009 and includes more than 200 interdisciplinary research and education programs covering a wide range of physical, biological and social topics in both the Arctic and the Antarctic.

Antarctic Climate & Ecosystems Cooperative Research Centre (Antarctic CRC)

The Antarctic CRC is a partnership dedicated to the study of atmospheric and oceanic processes of Antarctica and the Southern Ocean, their role in global and regional climate change, and their impact on sustainable management of Antarctic marine ecosystems. The Antarctic CRC works closely with Australian and international stakeholders to ensure that the research focus remains relevant and the results are made accessible in useful forms.

The Antarctic CRC does research in five interconnected program areas:

Climate Variability & Change– Improving our ability to predict the impact of Southern Ocean processes on climate, sea level, marine ecosystems and the marine carbon cycle.

Ocean Control of Carbon Dioxide– Determining carbon dioxide uptake and its effects on the ocean, and relating ocean processing of carbon dioxide to predictions of human-induced global change.

Antarctic Marine Ecosystems– Exploring relationships among the biological patterns and processes of the marine ecosystems around East Antarctica and relating them to physical oceanographic processes to predict likely ecosystem impacts of climate change and assist in development of sustainable management strategies.

Sea-level Rise– Improving our ability to project and respond to future changes in sea level by increasing our understanding of historical sea-level change, documenting the factors that contribute to changes in sea level, and assessing likely impacts of rising sea level on Australian coasts.

Policy – Providing analyses of possible policy implications arising from the science research programs and addressing issues that will help Australia formulate its input to Antarctic and Southern Ocean affairs and manage its interests in the region.

Core Partners

  • Australian Antarctic Division
  • Australian Bureau of Meteorology
  • CSIRO (Marine & Atmospheric Research)
  • University of Tasmania

Supporting Partners

  • Alfred Wegener Institute for Polar and Marine Research
  • Australian Greenhouse Office
  • Australian National University
  • National Institute of Water and Atmospheric Research
  • Silicon Graphics International
  • Tasmanian Department of Economic Development