Tool time: NIWA scientist heads to the ice with a drill and a tape measure

 A tape measure and a drill will be pretty much all the tools a NIWA scientist needs when he heads to Antarctica next week.

Oceanographer Dr Mike Williams leaves for Scott Base on Wednesday as part of team trying to better understand the role of sea ice in climate change. The main aim of the project is to measure the extent and thickness of this year’s sea ice. Sea ice growth is a crucial component in climate models used to predict future climate, but Dr Williams says the information currently used in the models does not represent reality.

“What we hope to do is have some really good measurements that will help us understand the processes around how sea ice grows. It’s really filling in more details around the growth processes.”

The measurements are made in two ways: by using electromagnetic induction measurement instrument towed under a Basler BT-67 aircraft, and by a team on the ground. The two groups operate simultaneously with the ground team’s measurements used to ensure those made by the aircraft are correct.

“Satellites can tell us the area the sea ice covers but not its depth, which is equally important to know but harder to measure”.

Matching sea ice thickness above and below

From the air we use electromagnetic induction to identify changes in the electromagnetic field between the ice and the ocean underneath it, and convert these into measurements of sea ice thickness. This is the first time an aircraft has been used for this kind of work in Antarctica.

Meanwhile, Dr Williams’ group will be on the ice making their own measurements.

“We measure by drilling a hole and using a tape measure. It’s very low tech but that’s the attraction. It’s been done this way for so long that we have a very consistent measurement through time.”

However, the spatial coverage of the old manual method is low. It is expected the aircraft will cover about 2000km, while the ground team will notch up between five and 10 per cent of that. Dr Williams’ trip will take just over three weeks but this is the first part of a two-year project that will also link with an American icebreaker coming to the ice early next winter and then see the return of the aircraft to measure the end of the ice growing season.

“This year is all about making sure everything works.”

Sea ice thickness affects New Zealand wind patterns

Dr Williams says the research is important because sea ice has a key role in moderating deep ocean circulation and it can play a role in where the westerly winds sit over the Southern Ocean and south of New Zealand.

“Because it provides a sharp edge between water and ice and it changes the dynamics in the atmosphere, it can potentially move westerly winds either closer to New Zealand or potentially further south. That links into how it impacts on our weather.”

The team comprises scientists from NIWA, the universities of Otago, Canterbury, Tasmania and Canada. The research is funded by the Deep South National Science Challenge, of which Dr Williams is Director.