Student's Antarctic sea ice research richly rewarded

By Angela Gregory

Contributing to the search for the "holy grail" of sea ice thickness in the Antarctic has earned science student David Dempsey a $10,000 scholarship.

Mr Dempsey, of Otago University, was one of three scholarship winners announced at this week's annual Antarctic Conference in Dunedin.

The 21-year-old, who is completing his masters degree in physics this year, also won second place for his student presentation at the conference which had as its theme "International Polar Year and the Next Generation".

Mr Dempsey said his interest was in the study of platelet ice which formed in the Antarctic depths and floated to the surface to attach to sea ice above.

His investigations used computer modelling in an effort to assess the overall thickness of sea ice.

That was important as the thicker the ice sheet, the longer it stayed around in summer, reflecting visible light off the white ice surface which penetrated through the Earth's atmosphere, taking energy with it.

It was important that process took place before the light was absorbed in the ocean or land and re-emitted as infra-red radiation which trapped greenhouse gases in the atmosphere and contributed to global warming.

Mr Dempsey said satellite imagery could show the extent of sea ice but not its depth. Drilling could establish depth in specific locations, but with 20 million sq m of ice that was not feasible for gaining an overall estimate.

Existing models had also not taken into account the contribution of platelet ice, which altered the growth rate, thickness and structure of sea ice.

"The holy grail of sea ice is finding out how thick it is."

Mr Dempsey said until he began is research he had never realised how much sea ice there was - greater than the size of South America.

He visited Antarctica last November for his research during a comprehensive study of first-year sea ice in McMurdo Sound. He needed a large data set with which to compare his computer simulation results.

"It was great fun but hard work as you only get down there once and have to make the most use of the time."

Dr Mike Williams, a Niwa oceanographer, was the sea ice and southern ocean processes event leader and said Mr Dempsey was the youngest in the team by about six years.

"He was fantastic in the field and worked really hard. We got to do all the fun work like drilling while he was happy to sit in a freezing container room and do all the boring and laborious measurements without complaint."

Dr Williams said Mr Dempsey's research was important and looked promising. "He is developing numerical techniques to get to a problem we find a bit intractable ... It's really exciting, a fresh approach."

Mr Dempsey's New Zealand Post scholarship had provided him with $10,000 towards his studies.

Another two student scholarships were also awarded. The Kelly Tarlton scholarship went to Kathryn Lister, of Otago University, and the Helicopter New Zealand scholarship to Fiona Shanhun from Lincoln University.

- NZ Herald

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