The TIDEx Campaign on Darwin Glacier: Part 5 – On Darwin

Briefly, what are our science goals at the glacier: The behaviour of Antarctica‘s glaciers and their extensions onto the sea, the ice shelfs, is variable. Some are relatiely stable, others seem to lose considerably ice in a warming environment with glaciers flowing significantly faster than in the past. At the grounding zone, the transition from glaciers to ice shelfs occurs. Our field measurements, right at this location, help us to get detailed insights into how glacier and ice shelf interact. For me this is a bonus for my main scientific interest, the interpretation of remote sensing satellite data acquired over these areas.

Our Twin Otter flight back to Scott Base was cancelled in the early morning.
Since the science part is done we enjoyed a sleep in until lunchtime. As the sun came out from behind the clouds it became quite toasty in our tent.
We are sleeping on 3 mats with a sheepskin rug on top, also we have four ‘nested’ sleeping bags; a cotton outer bag to protect from snow, a synthetic sleeping bag with a down sleeping bag inside it to keep us warm and a fleece liner to protect against smelly scientists. We are using our jackets as pillows which hide the block of chocolate underneath.
It takes about half an hour every morning to wiggle out of the sleep kit and into the polar clothing. Better not leave your boots outside otherwise they might be frozen and filled with snow.

Antarctica embodies the last pure wilderness on earth.
Since the early polar explorer, it has been the stage of many endeavours and a place where heroes were born. But Antarctica is also a pristine and sensitive environment full of native beauty. It is home to plants and animals and simple life forms have even been discovered at high latitude.

Today we were working up stream of the grounding line.
From here we could overlook the Darwin Glacier and enjoy the view of this remote part of our planet. This spectacular scenery reminded us about the privilege of conducting research in Antarctica.
A blue sky and mild temperatures are a big contrast to the blizzard we had when we arrived.

This is our fourth week in Antarctica and we start to make certain things.
Olli dreams about sitting on the green grass under a willow tree and misses a lamb chop (with mint sauce). Dana is looking forward to the skiing season in the European Alps after riding on the sledge for many kilometres on the bumpy Darwin glacier. Ekki would enjoy seeing the sun actually set.
Since there is no wildlife so far south, I miss my little parrot Kia, who wakes me up early morning’s with her tweet.

Within the last two weeks temperatures have been around -10 to -15C during the daytime. Although we experience 24hrs of daylight each day we even have to wear sun cream at night.
By the summer solstice, on the 21st December, everywhere south of the Antarctic Circle (66 degrees South), the sun will shine for an entire day.
In some places all this solar radiation can melt the ice on the surface. This leads to turquoise blue melt water ponds and large melt water channels; luckily, as it is early summer, the lake and rivers on the Darwin Glacier are still frozen and we can travel across them.
We already see the first sign of surface melting so we need to get our research done before it gets too hot out here!

While driving around with our skidoos we came across a line of boulders today.
The Darwin glacier looked like a giant frozen river. Similar to liquid water in rivers; glacier ice is flowing down the slope driven by its own weight. Where 2 glaciers converge they mark the beginning of a line of boulders laying on the surface.
We can track these features over time to estimate the velocity of the glacier.
As the ice continues to flow, towards the ocean, the boulders on the surface are buried in snow, out on the Ross Ice Shelf. If they reach the edge of the ice shelf they might be transported far away from Antarctica with an ice berg.

Its spring tide on the Darwin glacier and this marks the half way point of our stay on the ice.
Today the difference between low and high tide is 1.2m and the processes that we are interested in are most pronounced. While this is a very busy time for the installed field station we are filling gaps in our ice thickness maps.
When resting in our tents the constant ruffle of the blown snow is only interrupted by the creaking of the bending ice bellow.
Or maybe it’s just dinner time and I’m hungry!

Around our camp the surface of the glacier consists of bare ice.
Precipitation events are rare and strong glacial winds blow away every single snow flake out onto the ice shelf. Within the past week we have experienced wind velocity up to 45 knots reducing the temperature down to -20 degrees. This is not just cool its ice cold. Inhaling the air through your nose instantly freezes the moisture inside your nostrils.
This feeling of freshness lets us forget that we have been wearing the same clothes for nearly 2 weeks already. YUCK!

OPHEW, we just come back after the 2nd 12hr shift of ice thickness measurements. Why is this marathon really necessary?
The tip of an ice berg shows only 10% of its entire thickness. This means that an ice berg with 10m above the ocean has a 90m keel below the surface.
We can apply this principal to floating ice shelf and simply measure the surface elevation to invert it for ice shelf thickness. However close to the grounding line where we are the ice shelf is filled into by the Darwin Glacier. Here the ice is not freely floating and we cannot apply the ice berg principal.
Consequently we take our rustic wooden sledge for a drive and measure the ice thickness with radar. This takes a long time and the ice surface is very rough.

Good Food, Good Mood

The Darwin Glacier feeds into the much larger Ross Ice Shelf.
Over the transition between grounded and floating ice the position of the tide increases. Today we distributed seven highly sensitive tilt meters across the grounding zone to measure the flection due to the tide.
These movements are necessary to calibrate our space borne observations back at our offices. Our tilt meters can measure surface bending down to 1/1000, holy cow!

Added annotation:
* Nipp tides occur when sun, Earth and moon form a right triangle (crescent). Then high tides are lower and low tides are higher than usual. A spring tide happens when sun, Earth and moon are arranged along a line (full or new moon). Now the opposite occurs: High tides are higher and low tides are lower than normal.

Sun is shining, the weather is sweet.
An early morning call from Scott Base notifies us that a squadron of twin otters will arrive in one hour. A few moments later we hear the growling of the plane on the horizon.
After they landed the pilot George and Alex used their bare strength and juggled all our cargo out onto the ice.
After feasting on hash browns we leave our camp for the first day of installing our field station.

Is the early polar explorer conducting Antarctic research or a huge logistical challenge?
For our three week expedition we have survival gear, 500kg of scientific equipment, 200kg of food, 3 skidoos, 1 sledge, and 600L of fuel. These come up to about 3 tonne of cargo which is transported by four individual twin otter flights from Scott Base to our field site at the Darwin Glacier.
A group effort of many people and Scott Base is needed to make this work. But cooperation of the weather is essential!
Currently strong winds prevent our gear from arriving and confine us to our campsite. Fingers crossed for tomorrow.

In Antarctica we can find these different types of ice.
Sea ice consists of frozen ocean water only a couple of meters thick. Ice resting on land is created from the compaction of accumulated snow and can be up to 4km thick, however we are sitting on the Ross Ice Shelf this also floats on the ocean and is formed as land ice moves off the Transantarctic Mountains and detaches from the land.
Our base camp is located at 79° 52.50’ S 159° 45.08’ E. Today we measured the ice thickness at camp using a new radar system: 733m thick, we won’t get wet feet.

Added annotation:
* Katabatic winds are cold winds rushing down elevated slopes (“fall winds”). In polar regions they blow from the inland ice sheet, e.g. glaciers, shoreward.
** 35 knots correspond to 65 km/h, 45 knots almost 85 km/h.

Everybody is well and we had a good 1st night’s sleep. We woke up to a fresh breeze and a pleasant -12 degrees temperature.
We spend the day securing our base camp against the glacial winds.
The tents are anchored to the glacier and are protected by a high ice wall of blown snow. The wind weakened off as we finished building our frozen castle.
Our open air toilet looks like a throne with views over a kingdom of ice and snow.

We were worrying whether flight would be delayed or not, at 1100 Olly got final call for departure at 1200.
1hr later we were sitting in the twin otter to the Darwin Glacier.
Our flight route across Black Island and slope of Mt Discovery then impressive Skelton and Mulock Glaciers.
Flight conditions were ideal except for unavoidable turbulence at the Outlet Glacier.
We safely landed on ice and established camp.
Looks like a good spot for tilt meters!!!