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Nansen Ice Shelf, Antarctica 2015: Final Data Collection and Farewell to Jang Bogo

December 15th, 2015 by Maria-Jose Viñas

By Ryan Walker

Credit: NASA/Christine Dow

Credit: NASA/Christine Dow

Before it was time to recheck our GPS stations and download data from them, the icebreaker Araon arrived at Jang Bogo, bringing new scientists, a new helicopter crew, fresh food, and other supplies. Because of heavy sea ice cover on the bay, the arrival was in slow motion, taking most of a day from the time the ship was visible from the station until it stopped a few hundred yards offshore due to unbreakable eight-foot-thick ice. Thick ice often requires an icebreaker to back up a considerable way, then charge forward into the ice, breaking through either by pure impact or by sliding the bow up onto the ice, causing it to collapse under the ship’s weight. One passenger told Christine and me that it was “like being in a car crash — all day.” We’re quite happy that there will already be a clear path out of the bay when we take the Araon back to Christchurch. Before leaving again for a roughly week-long science cruise, the ship also dropped off quite a lot of equipment for the various science teams, including most of the instruments to be installed by our hosts, the Extreme Geophysics Group. This meant that the time between Araon’s departure and return would be very busy, with limited time to install instruments before most of the scientists leave on the ship. On top of this, we had several days of bad weather that prevented any helicopter flights. In order to finish our work on the GPS stations, we had to squeeze into a busy flight schedule, which meant that Christine and I would go on separate flights.

Credit: NASA/Christine Dow

Credit: NASA/Christine Dow

I was on the first flight on December 10, which began with Dr. Choon-ki Lee installing a new GPS station on a large piece of ice at the front of Nansen Ice Shelf that looks ready to calve off into a tabular iceberg. There’s a huge crack, miles long and sometimes over a hundred yards wide, which runs more or less parallel to the front of the ice shelf. Over the winter, the sea surface freezes and traps small icebergs in the crack, producing a fascinatingly broken icescape. Comparing ice velocities between this new GPS and our stations should let us monitor the calving process and learn more about how it works. When we moved on to check the first of our GPS stations, I found that it wasn’t operating at all. After checking the wiring, I worked out that the problem was either in the wire to the receiver, the regulator (the electrical component that connects the solar panel, battery, and receiver), or the GPS receiver itself (potentially big trouble) — but had no idea which one. I pulled out those three components to check back at Jang Bogo, and we secured the rest of the station and moved on. Fortunately, after an unpromising start, the two other GPS stations we visited were working perfectly. While downloading the data, which involved about fifteen minutes of connecting my laptop and then sitting on the ice typing obscure commands, I was amused by how much this aspect of field work resembled the computer modeling work I usually do, though with vastly better scenery. We then returned to Jang Bogo with two stations in good shape, two yet to be checked, and one hopefully to be repaired.

Christine says: It was getting worryingly close to the time when we would be leaving the Antarctic and we still had some data to collect and the GPS to fix. I found that the GPS problem had been due to a faulty solar regulator and replaced it with a spare back at base. Luckily I managed to piggy back on a flight out to the Nansen Ice Shelf with the Extreme Geophysics Group while they were putting out seismic stations. Replacing the GPS was quick, with the satellite lights blinking encouragingly; now we just have to hope the system will continue working for the next couple of months. At the next station, I downloaded the data while wind blew some loose snow all over me and the computer. I probably looked a little like a snowman by the end of that. The final job was to replace the tethers on the last GPS (see our previous blog post). It was not without sadness that I waved goodbye to the plucky little machines, which would sit out on the ice on their own until the end of February. At that stage one of our Korean colleagues who is overwintering at Jang Bogo will collect them for us and send them back on the ship.

Speaking of the ship, we’re off. It is due to arrive tomorrow and we will set sail for our 7-10 day ‘cruise’ back to Christchurch in New Zealand. Its hard to believe we’ve been here 5 weeks already and it feels a bit strange to be packing up and leaving. We’re hoping for some wildlife spottings on the boat and more importantly not to be completely debilitated by sea sickness. Internet is not readily available on the Araon so we will report back when we reach dry land. Wish us luck!

Goodbye, Jang Bogo! (Credit:NASA/Christine Dow)

Goodbye, Jang Bogo! (Credit:NASA/Christine Dow)

Nansen Ice Shelf, Antarctica 2015: First Data Collection Day

December 14th, 2015 by Maria-Jose Viñas

By Christine Dow

Credit: NASA/Christine Dow

Credit: NASA/Christine Dow

The big day had arrived. We were due to fly to our tiltmeters to collect the data that they had been gathering for two weeks. once this was the first time we had ever set these instruments up in the field, all fingers were crossed that we had been precise enough in initially leveling the meters so the data were in range and also that the solar panels hadn’t ended up covered in snow.

We had a spectacular flight, cutting over the end of Priestley Glacier and skirting helicopter-sized crevasses on the mountain behind our field site. Despite a bit of wind on the Nansen ice shelf, it was as calm on the Comein Glacier as it has always been for our visits. It’s such a peaceful, sheltered spot that I feel a holiday cottage wouldn’t be amiss. Perhaps too long of a commute for an average Friday afternoon, however.

Credit: NASA/Christine Dow

Credit: NASA/Christine Dow

One of the tiltmeters (which are in black boxes) had become exposed and, because black materials absorb heat whereas white materials reflect it, had caused a bit of local melt which had trickled down the side of the box and refrozen. The upshot of this was that the entire box, battery, and straps were encased in some pretty solid ice. Fun! Commence some delicate hacking with ice axes so that we didn’t snap the wires coming out of the box. Finally having reached the interior, we nervously extracted the SD card and Ryan pulled the data off onto the computer. Success! Some excellent (and exciting) looking data showing tidal cycles. Tiltmeter two was easier because it hadn’t caused local melt of the snow so we could quickly retrieve the data. Again, some very interesting outputs. We want to thank John Leeman, an engineer from Penn State, for building us some happily working tiltmeters. Of course having disturbed the tiltmeters I had to reset them back to full level, which required sitting for 10 minutes enjoying the view while very delicately adjusting the little leveling legs.

We had just enough time to collect data from one of the GPS closest to the tiltmeters. All looked well apart from our tethers, which had come loose because of melt on the surface. We had one bamboo tether and one metal peg. The metal had heated up and melted a groove in the ice as it was pulled along, whereas the bamboo had stayed where it was supposed to. We tightened the wire as much as possible but we would have to return to this site with some more bamboo later.

Credit: NASA/Christine Dow

Credit: NASA/Christine Dow

Dinner back at base was a happy affair, having achieved success for at least three of seven of our instruments. The chefs had even made some pizza for us, which was a nice treat. The only unfortunate aspect of the day was that I had forgotten that in areas with 24 hour sunshine and highly reflective snow surfaces it is essential to put sunscreen up your nose as well as on it. Burnt nostrils are not fun, but they’re worth it for some nice data.

Nansen Ice Shelf, Antarctica 2015: Life at Jang Bogo

December 3rd, 2015 by Maria-Jose Viñas

By Christine Dow

Jang_Bogo

Day to day life at the base station is varied primarily by timing of our field expeditions. We’ve had some very busy days getting equipment ready, deploying and checking our gear. In between, however, we are essentially operating as we would do at the office. We have set up base in the ‘Extreme Geophysics Group’ laboratory joining seven Korean scientists. Work tends to happen six days a week, with Sunday as a break (and no 7 am wake-up music!). Also on Sundays there are sometimes mini-expeditions. For example, a group of us walked a couple of miles over to Gondwana, the German base, which is semi-inhabited (two people are there at the moment keeping things ticking over). We were hoping for some “Kaffee und Kuchen” (coffee and cake) but couldn’t find anyone around. Instead we looked at rocks ejected from the nearby volcanic Mt. Melbourne, found some lichen and watched the many skuas (seabirds) flying around. We also ventured down onto the sea ice and found a nice ice slide which entertained us for a while (who said scientists couldn’t be silly).

Seal1

Last Sunday, Ryan and I joined a short expedition over to Mario Zucchelli, the Italian base. Recently a crack, or lead, has opened up in the sea ice so it’s no longer safe to drive the heavy Piston Bully tractors over. As an alternative, the Koreans and Italians both drove up to the crack and we exchanged passengers by hopping over the gap (it’s not really that big). There were some nearby Weddell seals hanging out near the open water, which we got a good look at. You have to be careful not to get distracted and wander into one of the seal holes which are just a bit darker than the surrounding ice – that would be a chilly surprise!

 

Mario_Zuchelli
The Italian base was built 31 years ago so looks a bit more worn in than Jang Bogo but is very cosy inside. We were given a tour and fed some excellent espresso and gelato. It was really interesting to see the differences between the two bases and even the landscape. Despite being only 6 miles (10 km) apart, the rocks around Mario Zucchelli look much more weathered and eroded compared to much rougher terrain at Jang Bogo, perhaps due to the closer proximity of the volcano to the South Korean station.

LifeatJB3

At Jang Bogo, another big difference is the food and is the subject of much conversation with the Western scientists. There has been a large range of foods produced which keeps things interesting. A lot of it is a surprise since we can’t read the Korean menu, although being able to cope with spicy food is definitely an advantage (Ryan is better with this than I am). By far the best meal was Korean BBQ evening where we cooked meat and prawns on a hotplate right on the table and had a brilliant array of salad leaves (grown in house) and sundries to eat with the meat. What a meal!

Nansen Ice Shelf, Antarctica 2015: Second Day of Installation

December 1st, 2015 by Maria-Jose Viñas

By Ryan Walker

TM1_pic

Our second day of installing equipment was on November 21. After a cloudy day off, we had perfect sunny weather.

We began by installing our two tilt meters at Comein Glacier, which flows into the Nansen Ice Shelf through a small inlet just north of the much larger Reeves Glacier. Most of an ice shelf floats freely up and down with the ocean tides, and the ice only flexes in a relatively narrow band between the floating ice shelf and the grounded glaciers that flow into the shelf. We chose this location (about 35 miles upstream of the ice shelf front) because the flexure zone is particularly wide (over three miles) and there is a broad strip of over 900 yards of ice that floats at high tide and rests on the ground at low tide. (We know this thanks to satellites that measure the height of the ice surface using lasers or radar, and to comparisons between satellite radar images that detect ice motion.) As it turned out, this area is the most spectacular place we’ve yet visited, surrounded by gleaming white snow- and ice-covered peaks.

Installing tilt meters is rather tricky, since the instrument has to be almost perfectly level. After two Korea Polar Research Institute safety guides checked the area for crevasses (large cracks in the ice), we dug through about two feet of snow before finding solid ice. To keep the tilt meter level, we constructed a table from a piece of plywood supported by three aluminum pipes drilled into the ice. The pipes passed through holes drilled in the plywood, which rested on hose clamps fastened around the pipes. By adjusting the hose clamps, we leveled the plywood before placing the plastic case containing the tilt meter on top of the table. The tilt meter itself has a triangular base with three adjustable screws so it can be leveled on top of a flat plate at the bottom of the case. To do this, I had to attach a cable from the tilt meter to my computer to get readouts of the angles while Christine very carefully adjusted the screws. Once we were satisfied that the instrument was level, we hooked up a solar panel and battery for power, just as we did for the GPS stations. Finally, we buried the case and table in the snow to prevent any melting of the ice supporting the table, which could put the instrument out of level.

GPS_installday2

After sandwiches and coffee in beautiful sunny weather (certainly the most scenic picnic lunch I’ve ever had), we took some time for a school outreach project that Christine will tell you about. Then we flew back out onto the Nansen Ice Shelf (which is much windier) and installed our two remaining GPS stations with no trouble (other than a chilly half hour waiting for the helicopter to return) to complete a successful day in the field. Now we need to wait about two weeks before collecting data, so that we can see what happens to the shelf as the ocean tides go through a full cycle from spring (largest difference between high and low tide) to neap (lowest difference).

TM2_pic

Christine says: I’m involved in a program coordinated by the United Kingdom Polar Network called “The Antarctica Day Flags Initiative”. School classes design flags for Antarctica Day (which is December 1, the anniversary of the signing of the Antarctic Treaty in 1959) and then scientists and researchers take them to the Antarctic and take photos of them out in the field. I had 21 flags from two schools (Yardley Hastings and Northrepps Primary) so we attached these to poles and took some pictures in front of some beautiful icy cliffs with our Korean colleagues.

NP_picture YH_picture

Nansen Ice Shelf, Antarctica 2015: Scouting Our Field Sites by Helicopter

November 17th, 2015 by Maria-Jose Viñas

By Ryan Walker

On our first full day at Jang Bogo, we weren’t expecting very much to happen. The majority of our equipment wouldn’t be arriving for another three days, so we thought we would settle in and learn about the basic amenities of the station — food, showers, laundry, wifi, espresso machine. (I’m not joking, there really is an espresso machine. You can learn all sorts of unexpected skills living in Antarctica.) But then the day turned out to be sunny and clear, perfect for flying, and one of our collaborators, Dr. Hyeon Jae Yoo, came and told us that he had reserved a helicopter for that afternoon to scout out our field sites.

Choosing field sites can be rather tricky. We had spent quite a while looking at satellite images and computer model output in order to estimate where the processes we wanted to study would likely be strongest. For GPS measurements of ocean tides causing ice motion, we wanted to be more in the middle of the ice shelf, away from the islands and rocky outcrops that pin its margins in place. For tilt meter measurements of ice shelf flexure, we would need to be near the landward edge of the shelf — most of an ice shelf floats freely up and down on the tides, and the bending happens in a narrow strip (maybe a few kilometers wide) between the floating ice and the ice resting on the land. Field site selection is then a balance between finding the ideal place to collect data and finding places where you actually can collect data. Crevasses (large cracks in the ice), very uneven ground, and ponds formed by melting of the ice surface can all prevent setting up instruments. In the end, it’s essential to get an in person look at your sites, preferably before you’ve dragged all your equipment there.

Large crevasses in the ice.

Large crevasses in the ice.

This was my first helicopter flight, and since it was my birthday (what a celebration!) Hyeon Jae and Christine insisted I should sit up front. Taking off is sort of like riding in a glass elevator. Flying in a helicopter is very different from flying in an airplane. Being able to go low and slow (or hover) gives great views. We were able to circle our GPS sites at about 10 feet off the ground, and touch down briefly (with the rotors going) at our tilt meter sites to test the firmness of the snow. Our GPS sites are all on blue ice, with no snow cover, and look favorable for installing the instruments. We’ll just have to shift a few of them a short distance so they’re on ridges rather than hollows — although the ice is pretty flat, this matters when the ice surface starts to melt later in the summer and the water flows downhill. Our tilt meter sites are on a snow-covered area, so we will have to dig down to ice (or at least very firm snow) to get a solid base so we can install the instruments level. This is really important because the ice only bends a little, so the tilt meters measure angles less than half a degree. (That’s a little less than 1 foot up per 100 feet across.)

Overall, we were very happy with the results of this flight. Our field areas look good, and we got truly spectacular views of the ice shelf and the rocky hills surrounding it. I shot video with a NASA-provided GoPro, and it came out great, even though all I had to do was point the camera at the windscreen and try to hold it still. The files are too large to post from Antarctica, but the best scenes should be part of the final video that Goddard will produce when we’re back home. Thanks to our pilot, Dominic of Helicopters New Zealand, for a smooth and safe flight.

Notes from the Field