Keeping tabs on the Totten Glacier

Located in East Antarctica, 150 kilometres from Australia’s Casey research station, the Totten Glacier is currently the subject of significant research efforts by Australian and international scientists.

The glacier drains the biggest ice catchment in East Antarctica, contains enough ice to raise global sea levels by more than three metres were it all to melt, and is thinning faster than the region’s other glaciers.

For the last two summers Hobart-based researchers have measured Totten Glacier as part of the TIDE project (Totten Glacier Ice Dynamics and Evolution) delivered as part of the Australian Antarctic Program.

Australian Research Council Antarctic Gateway Partnership sponsored IMAS PhD student Madi Rosevear this year joined the TIDE team, alongside Australian Antarctic Division (AAD) field guide Nick Morgan and researchers Professor Paul Winberry (Central Washington University under contract to the ARC Antarctic Gateway Partnership) and Dr Ben Galton-Fenzi (AAD).

“The aim of the project is to measure how the Totten Glacier moves, how quickly the ice flows, and how the surface elevation changes due to the tides” Ms Rosevear said.

(Image, left, helicopter delivering tower parts)

“We measure movement using high precision GPS.

“We also measure melting at the base due to contact with the ocean. Then we can  combine the datasets to look at how much melting is happening and what the response of the glacier is - for example, how much it speeds up due to the melting.

“Most days we’d fly out from Casey research station in either two helicopters or a Twin Otter plane, which takes about an hour.

“Our first job was to find towers that were installed last year, dig them out, download the data from the instruments on them, and then refurbish the towers.

“The basal melting measurements are taken using a radar instrument called an ApRES (Autonomous Phase Sensitive Radio Echo Sounder), which we install at locations on the glacier on top of towers – they’re needed because there’s two to three metres of snowfall on Totten Glacier each year and otherwise the instruments would get buried.

(Image, right, Madi Rosevear working up a tower. Credit: Ben Galton-Fenzi)

“For each tower we’d build an extension, put the instruments on top of the new structure three or four metres above the snow, and then set them logging again.

“That was the highest priority task and we did it at six locations,” she said.

Ms Rosevear said the project also required the TIDE team to camp on the ice for up to five days at a time.

“Sometimes when we had other measurements to take we’d be left by the plane and camp on the glacier to do work like shallow seismic testing with a hammer, where we’d hit a metal plate with a hammer and monitor the sound waves rebounding back.

“We had planned to use explosives as a more powerful seismic source to measure the thickness of the water column underneath the glacier and to look at the structure of the sediments below the water column.

(Image, left, Nick Morgan doing seismic hammer testing)

“But, remarkably and unexpectedly, we could still see down to the seafloor using the hammer seismic technique, even though the ice is very thick, so normally you wouldn’t expect to see a signal that you could separate from the background noise.

“While doing that we discovered that part of the Totten Glacier that we thought was grounded is actually a floating ice shelf, which could be significant for the glacier’s contribution to sea level in the future.”

Ms Rosevear said being in the Antarctic felt like a huge privilege.

“Being in the field is hard to explain.

“The moment when you get dropped out there and the aircraft leaves is pretty amazing.

“All of a sudden it’s quiet and the landscape feels vast, it’s a pretty cool feeling.

(Image, right, Camp on the Totten Glacier. Credit: Ben Galton-Fenzi)

“It’s one of those moments where you think, wow, I’m really glad I’m not alone.

“One of the nicest things about working down there is the teams that I’ve worked in.

“We were lucky in having a really nice team with a great dynamic and lots of laughing.

“I love working there.”

The ARC Antarctic Gateway Partnership sponsored the logistics for the Totten Glacier field season.

Authorised by the Executive Director, Institute for Marine and Antarctic Studies
3 May, 2018