Visit at Asuka Station

Today, Nicolas Bergeot and Olivier Francis were accompanied by a crew of PEA lead by the field guide Guenther to visit a continuous GPS station, which was initially setup by IceCon in 2012 at Asuka (an old Japanese station). This time the station measured continuously until the end of January 2015 when the GPS receiver went into an unexpected standby mode in spite of full batteries and operational solar panels.

Nico will have to investigate as to why this has been the case so that we can modify the system for the coming year. Other than that our phase sensitive radar has been setup and we are currently testing the overwintering mode and the corresponding Iridium data transmission.

Tomorrow, Nico and Sanne, the chief of the field guides, are going to head out to Yet Nunten (close to the Antarctic plateau) and see how the continuous GPS is doing over there. Once all material has been successfully tested at PEA, we will be preparing the traverse to the coast which will hopefully commence in a few days from now.

Picture taken by Erik Vroonem

 

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Windy Skidooing

In the morning we had various meetings clarifying the last details about the planned field work on Roi Baudouin Ice Shelf. The IceCon team will part together with Benemelt in a larger team of 8 skidoos. It was hence a timely endeavour to (re-) acquaint ourselves with the insights of skidoo-mechanics and handling. Our field guides Sanne and Guenther led us for a nice ride around the blue ice fields around the windscoop of Utsteinen. Parallel we started unpacking and testing our scientific equipment and we were happy to find most of the things which our colleagues (Frank Pattyn and Brice van Liefferinge) of ULB have left behind last year.

The first containers from the boat unloading have arrived, containing among others a nice tasting beer from a Belgium beer company which is known to fund excellent scientifc research in Antarctica (see Benemelt blog for details). Tomorrow Nicolas Bergeot will leave to maintain the permanent GPS station near Asuka, which is our first scientific target of this season.

Picture taken by Stef Lhermite, Benemelt

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Seamless Arrival at Princess Elisabeth Station

The Ilyushin flight took off as planned at 10:00 on a sunny morning in Capetown. About six hours later we arrived at the notouriously windy airfield of Novolazarevskaya Station. In the upcoming days stormy weather is expected for the Dronning Maud Land area, and luckily the BELARE team was able to catch the feeder flight to Princess Elisabeth immediately (while all other groups were transferred to shelters). At about 20:30 local time we were welcomed by the station team waiting for us in the background of the familiar Utsteinen mountain. It is nice to be back and operations at the base are at full swing because the supply vessel has already reached the ice edge two days ago. So far everything is on time and even ahead of schedule. After a long day, we are looking forward to hop into to our (already prepared!) beds and will commence unpacking and field training in the coming days. For now we enjoy the magnificent view of the Sor Rondane mountain range surrounded by ice, ice and again ice. Somehow you never get used to that surrounding.

 

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ALCI meeting and scheduled departure

At today's ALCI meeting the flight from Capetown towards Novolazarevskaya has been confirmed. We will be leaving on Friday morning at 10:00

with a relatively newly commissioned Ilyushin 76. Weather conditions are favourable at the moment and we hope that the entire team of 7 BELARE (Belgian Antarctic Research Expedition) scientists make it without problems in one go using a feeder flight from Novolazarevskaya to Princess Elisabeth Station with a modified Basler DC3.

At the briefing we met many old science friends from other nations, particularly from the British Antarctic Survey (UK) and the Alfred Wegener Institute (Germany). In total the flight will transport 52 people for various scientific projects. Our bags are packed, and if everything goes as planned we will be leaving Capetown in record-breaking transition period of only two days.

 

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Start of the last field season

Finally, the last leg of the field work of the IceCon project. This time Dr Reinhard Drews (ULB) and Dr. Nicolas Bergeot (ROB) will form the team to finish up the last measurements for the project and retrieve the data that has been collected so far. Today they arrived safely in Cape Town for the first leg of the voyage. It is planned to fly out on Friday to Antarctic, but all depends on the weather conditions that don't look so well so far.

Reinhard (left) and Nico, ready for departure in Brussels Airport (5 Januray 2016).

The field work has - as usual - a very tight plan, including travel to the ice shelf to retrieve radar instruments and reinstall the GNSS/GPS systems for another year of deployment that are part of the Tweeting Ice Shelf (http://tweetiniceshelf.blogspot.com - @TweetinIceShelf on Twitter). A second set of radar measurements the the ApRES system (phase sensitive radar) needs to be done on Derwael ice rise, in order to get the vertical velocity field within the ice mass. The geodetic GNSS will also be dismantled there. Finally, a series of further measurements with radar (high and low frequency + ApRES) will be carried out in the vicinity of the grounding line, enabling to have sufficient data to constrain the ongoing modelling of the deglaciation in this area.

The two other cGNSS systems on rock need to be revisited as well, checked, data downloaded and put in operation again. And all this in one month.
We'll keep you posted on the events, live from the field.

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The ice-core drilling challenge

Ice core drilling is challenging and therefore, very exciting. This season, we had set the objectives very high for the ice core drilling team, Jean-Louis Tison, PhD student Morgane Philippe, and mechanic Kristof Soete, who were all very happy to take that challenge! If you remember well, in 2012, we drilled 120 meters in 11 days, and we encountered some problems on which IPF and Eclipse Ice Drill have been working since then. This year, we planned to drill 3 boreholes: two shallow-firn cores of 30 meters and one ice core of about 160 meters, in 17 days.

After setting up and being stuck for 2 days by the first storm, we could finally start drilling the first 30 meters at Derwael Ice Rise on the 3rd of December. This drilling and the next one went really smooth. Almost every run yielded a 1.40m beautiful piece of firn core, with very few thin ice layers (less than 1mm). The two 30m boreholes were drilled within 3 days, just before the second storm hit us. These boreholes were also “televiewed” which means that we recorded a digital image of the borehole with a special camera, at very high resolution.

On the Roi Baudouin Ice Shelf, drilling the third hole was not such an easy task. There are several reasons for that: one of them is the number of ice layers, sometimes 20 cm thick that the drill encounters regularly during its progression. Another reason is that we reached ice much faster on the shelf, (~30 meters) and the firn – ice transition is always a difficult part to go through, since we have to adjust many parameters. For example, we had to change to more powerful core dogs, designed by IPF, otherwise the drill head could not break the cores anymore.

 

But the real problems started at 54 m, when the drill got stuck at the bottom… after trying all we could do without damaging the drill (blowing the fuses, using the hand crank, leaving the cable under tension for one night), we decided that we would need to poor diluted antifreeze down the hole, as it has been done in other drilling programs. It was done within 24 hours thanks to a very efficient logistical help from IPF and a tube transport system. To everyone’s relief, the drill was loose the next morning. Surprisingly, the core was in very good state in the barrel, so we decided to try restart in the same hole, and it worked! From that moment, we worked non-stop during two days and two nights, with the whole team taking turns to drill as deep as possible, slowly removing the leftover antifreeze at the same time. Unfortunately, time was running out and we could not miss our plane, unless we wanted to stay in Antarctica until February. We managed to go down to 107m, instead of the 155 meters needed to reach the ocean, but this already represents a lot of valuable material, as well as a very informative televiewer image of the borehole, showing precisely every single ice layer, a signature of about 200 years of the surface melting history in this typical place on the ice shelf. We will soon compare it with all the other data: those from the different radars used in the IceCon project, but also the data from the Benemelt project.

On travel, storms and science

Back at the station!! And here a very short overview of the accomplishments of the IceCon project. Over the next couple of days, more in-depth accounts will be given here.

We left PEA on 27 November in the evening for a night and a day travel to Derwael ice rise. Camp installment went smoothly, but after one day we got caught in a storm, and not a nice one. Atmospheric pressure dropped very quickly, winds picked up and snow drift was amazing. Furthermore, it was quite warm, meaning that snow melted in contact with persons and goods. We had to leave are tents and sleep in the containers for 2 days. The storm lasted for more than two days and it took another day to clean up camp. For science, this meant a delay, but it is amazing how quickly we picked up after that.

 

Getting the contents out of the tents during the storm at Derwael ice rise

 

The drill hole of 2012 was retrieved (under three meters of snow) and was again televiewed: this is an instrument that images the interior of the borehole. It was done in 2012 and we hope to see changes in the internal structure when comparing with the 2014 data. The cGPS station was again covered under a lot of snow (as usual), but also here the system worked perfectly through the Antarctic winter and all data were retrieved. In a couple of days Nico managed with the help of Kristof, Raphie, Cristophe and Jan to get also this station installed again for another (third) winter. Another task was to drill two 30 meter firn cores at either side of the ice divide of Derwael. While it would normally take 2 days for each of them, it was remarkably done in less time, including the installation of the drill equipment at either site (4 kilometers apart). We noticed from the drilling in 2012 and subsequent radar surveys that the accumulation variability across the ice divide is very large, with one side having an accumulation rate that is twice as high as the other, due to a so-called foehn effect, leading to more precipitation at one side and erosion due to sublimation and wind scouring at the lee side of the ice rise. If you are in the field, you have the impression that the ice rise is a gently sloping, hardly noticeable rise in the surface elevation, but its effect on mass balance is quite impressive. All boreholes were subsequently linked through radar profiles with our snow radar. Finally, we installed also a whole network of pRES measurements. This new type of radar enables us to measure directly change in the internal structure of the ice, which is necessary to identify the effects of snow compaction and strain to interpret the cGPS data. We already identified that the surface of Derwael ice rise is thinning, but we wish to reveal by how much exactly and what the processes are behind. The pRES data will complement the results from our coffee-cans we installed two years ago and have been functioning for the last two years. Unfortunately, only two of them were still operational (again under three meters of snow!) and we had to abandon them this time. However, the pRES will hopefully give more detailed insight in the dynamics of the ice. Our work at Derwael ended again with a storm, this time less forceful (we could stay in the tents), but it was again a two-day delay (storm + getting the camp cleaned up).

 

pRES measurements at Derwael ice rise

Digging out the cGPS station

 

In the morning of 8 December we moved the camp to the Roi Baudouin ice shelf (RBIS) for another series of exciting measurements. One of them was the third drilling through the ice shelf. Although such a floating ice shelf looks relatively flat with a constant ice thickness between 250 and 300 m, some areas are significantly thinner. These are elongated depressions hardly a couple of hundred meters in width, but stretching from the grounding line (contact of the Antarctic ice sheet with the ocean) to the edge of the ice shelf (more than hundred kilometer). We already found out that these depressions are formed by deeply incised channels at the bottom of the ice shelf so that ice thickness is around 150 m. These features are presumably formed at the grounding line and transported (advected) with the ice flow, but they may also indicate melting at the bottom of the shelf. Therefore we carried out deep drilling through the ice shelf and complemented this with shallow radar surveys as well as pRES measurements that directly can measure bottom melting (if present). The shallow radar was also used to link the borehole in the shelf with shallow cores as part of the BENEMELT project of Jan Lenaerts. The drilling went not so smoothly, but after some interventions, we were capable to drill to 107m. Several pRES measurements were carried out across the channels and the instrument was then finally buried in the snow and left for the winter. It will record every hour the vertical change in the ice shelf. Together with 2 other GPS instruments at the side of the channel to witness the flow, they will send their position every day. The latter is part of the @TweetinIceShelf project (more later).

 

Drilling through the ice shelf with the Eclipse drill

 

 

In short, and despite the bad weather at Derwael, the scientific programme was carried out completely. The drill didn't make it all the way to the bottom of the shelf, but what has been recovered is already a wealth of information that will be extremely useful in understanding ice-shelf dynamics. We wish to express our gratitude to the support at PEA, because it was quite something to make the different projects (IceCon, BENEMELT, SISMO) work together and change the plans according to the unpredictability of the weather.