This week at Davis: 10 February 2017
This week at Davis we have the ABC in town, we're doing deep field work on the Sørsdal Glacier and Amery Ice Shelf, and successfully replacing Trajer Hut.
The ABC visits Davis
When it comes to journalism, there are few greater prizes than a trip to Antarctica. This year, out of 36 applications to the Australian Antarctic Division from national and international media organisations, ABC Hobart won a gig. Peter Curtis (camera), Fiona Breen (Landline reporter), and Mark Horstman (science reporter, formerly of Catalyst) were thrilled to accept a two-week assignment at Davis and Casey.
Our mission was to make a range of stories for ABC-TV news and current affairs. The camera started rolling the moment we walked onto the tarmac in Tasmania. That first day became a remarkable travelogue from Hobart to Wilkins to Woop Woop to Davis, flying straight through in dream weather.
Penguins and petrels at Gardner and Bluff Islands starred in a story about their high-tech tracking devices. We followed tiny microbes having a vast impact on the Southern Ocean by releasing a cloud-forming gas that could cool the surface temperature of the sea. It turns out that the Sørsdal Glacier is a kilometre thicker than we thought, but are those vivid blue surface lakes draining underneath and speeding up the flow of the ice sheet? Where could a runway to provide year–round access to eastern Antarctica be located? We went to the Heidemann Valley and surrounding ridges to find out. And in an unexpected bonus, we filmed the first ocean sensor for the season being attached to an unsuspecting elephant seal.
These stories will be broadcast on ABC (once we get back and edit them) after 19 February. News is planning an Antarctic special across two nights on Sunday 19 and Monday 20 Feb. 7.30 will also run the glacier and microbe stories soon after. Different versions and little extras will appear on News 24 and online.
Thanks to all the scientists, expeditioners, field training officers, pilots, tradies, techies, wildlife and weather gods (and of course Kirsten and Sharon) that made them possible.
Geophysics on the Sørsdal Glacier
After a mid–season switch-over of staff, the Sørsdal Glacier project has moved its focus to geophysics. Christian and Eleri’s lake monitoring equipment was installed in December, and my goodness have there been lakes to monitor! Each time we visit the ice there is more and more water visible. The results should be very exciting.
Our work since then has been to put those results into context. We know the front of the glacier is floating, but no one knows exactly where on the glacier that flotation begins (the grounding line). Our first job was to use a seismic survey to measure the thickness of the ice and water cavity underneath along a flowline and pin down the location of the grounding line.
Our seismic source is created by hitting a thick steel plate with a hammer. The vibrations reflect off the base of the ice, and are recorded by our equipment. The thickest ice we have measured so far is 1.7 kilometres, and I’m always amazed that a hammer blow can travel all that way and still be detected. Although the Sørsdal is only 20 kilometres from station, there have been almost no reliable thickness measurements made before, so each measurement we make is adding a lot to our knowledge.
Our second geophysics task was to examine an old lake basin which drained last season. This site, which we have called the Channel Lake, is interesting because the drainage seems to have happened through channels below the surface of the ice. We’ve spent this week running ground penetrating radar (GPR) over the surface to try to pick up those channels and find out exactly where the water went.
There’s so much to learn about the Sørsdal Glacier, we could carry on working forever, but the temperatures are noticeably dropping now and the end of the summer season is creeping up. There is a lot of data processing to be done once we return, and then planning for the next season will begin again…
The Amery Ice Shelf and G3 weather station
The Amery Ice Shelf is host to some of the experiments managed and maintained by the Climate Processes and Change group. During the past week we visited the G3 weather station for a long overdue re-sitting. Without going into too much detail, here is some background on why the weather station ended in this predicament: it was four metres under snow!
Cold air dropping from the polar plateau, called a katabatic wind, picks up snow and drops it further downwind. Season by season more snow is deposited onto the Amery, where thin layers of snow becomes metres of snow.
After three days of excavating with chainsaws, shovels and ice axes, the team managed to free the station. During this process a few tons of snow and ice was removed to create a hole of about five metres deep! The mast and control boxes were then slowly lifted out of the hole, with great care taken not to damage the instruments, and placed at its new position a few meters up the glacier. A special thanks goes out to all involved in the big dig.
Lötter (Electronics Engineer)
Trajer Hut - Phase 4, replacement
Well! What can I say?
Mere weeks ago I was bemoaning the loss of a cosy melon and a wonderful landmark – now I can say the situation is well and truly rectified.
Since the previous melon departed a bigger and better deck has been built, which was a feat in itself. As we are heading into the hectic finale of the summer season, logistics play a big part in any undertaking that involves helicopters, so to get the deck and melon done in short order is awesome.
I was lucky enough to be chosen along with Ed (senior plant operator), Vas (departing winter electrician) and Val (a summer plumber who has wintered here previously). Between us we had almost zero melon building experience! Nevertheless, once the helicopter had dropped the last load of goodies off, we ripped into it. Thankfully, those who had organised the melon and all the supporting tools and bits had done a great job, and we had more than enough of everything to make it happen.
Thursday was a long day but fruitful, as we erected the whole shell and tied it down. Friday saw us tweaking the guy wires, sealing the external joints, setting up an improved communications mast, hooking in the gas and solar – and of course taking a group photo!
It’s big. It’s shiny. It is very, very orange. Inside it is roomy and warm, with walls that are like a blank canvas waiting for guests to share their thoughts…