National Institute of Water and Atmospheric Research (NIWA)

Antarctic visit to study sea ice

Scientists flew to New Zealand’s Scott Base, on the first post-winter Antarctica New Zealand flight last week, to study the growth and thickness of winter coastal sea ice in McMurdo Sound.

The scientists, from the National Institute of Water & Atmospheric Research (NIWA) and Otago University, are spending six weeks on the ice doing training, and setting up a pilot study, for an eight month research project which will begin in February and run through the 2009 winter.

Sea ice is a critical part of the Southern Hemisphere climate. It moderates atmospheric temperature changes by ‘locking up’ energy as it freezes, disrupting the ocean-atmosphere exchange of heat and moisture. Studies predict there will be a 34% decrease in annual mean sea ice volume in the Southern Ocean in the next century.

The thickness of the sea ice determines its strength, its ability to withstand and dampen the impact of waves, and controls the energy required to melt the ice.

NIWA marine physicist Dr Mike Williams says winter sea ice is one of the least understood aspects of the high latitude climate system, as simply gaining access to the ice is difficult during the winter.

“Satellites can detect the extent of sea ice year round, but don’t measure its thickness. To study that we need to be in Antarctica. The relative ease we have in working in McMurdo Sound is because of the support we get from Antarctica New Zealand and the Scott Base staff, especially the winter-over team.”

“A long-term underwater mooring will be installed in the northeast of the Sound which will allow our team to record oceanographic data on things like ocean currents, temperature, and salinity.

Sea ice thickness also has a direct impact on the multi-million dollar tooth fish industry and ship-based Antarctic tourism operators, because it affects navigation.

“The information we gather will help us answer critical questions directly related to sea ice extent and thickness - especially how it affects climate change. We will also be able to understand the influence industries working in the area might have by answering questions about how sea ice affects them. For example, access for fishing would be easier if there was less sea ice, but as the base of the food chain relies on the sea ice, fish stock could conceivably be reduced,” Dr Williams says.

The research is a part of a collaborative project between NIWA, the University of Otago, Industrial Research Limited, and Victoria University of Wellington. It is funded by the Foundation for Research, Science and Technology as part of a fund supporting International Polar Year research.

The full project will begin in February, with a team of scientists staying on the ice, at Scott Base, until October 2009.

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