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Arriving at NEEM

Posted August 3rd, 2009 by celene.carillo@oregonstate.edu
Ice sampling at NEEM.

Ice sampling outside Kangerlussuaq.

After a hectic day of preparation on Wednesday, we called it an early night to prepare for our 4:45 am wakeup the following day. The one easy thing about rising early here is that it’s always light, no matter what time you have to get up. We met the Air Force crew at the airfield and I boarded a C-130 for the second time this week. This time, though, we were much more tightly packed. First, there were 37 of us in the small area of the plane designated for passengers and second, we were all wearing or carrying our polar survivor gear—giant moon boots, ski pants, down parkas, heavy gloves and hats—which increased our collective size by at least 25%.

Even though it was packed, the flight north was spectacular. From the windows of the plane, we got sweeping views of the rugged mountains and glaciers of Greenland’s northwest coast. Jagged peaks rose out of the ocean, carrying massive burdens of ice. Small mountain glaciers cascaded down the rocky flanks of peaks, while wide rivers of ice wound and curved through the valleys below, collecting mass with each tributary. Eventually, the ice finally plunged into the sea, and met its watery foe. The casualties of their battle drifted through the fjords and out into the open ocean, white specks on a bright blue background. After two hours, we turned inland toward NEEM and all we could see was white.

We began our descent and soon I experienced the very unique sensation of a plane landing on snow. Next, we were blinded by a white light emanating from the back of the plane; the crew had opened the rear door, which formed a ramp down to the snow. Still moving at 20 or 30 mph, the cargo was “drifted” onto the runway. I don’t know how drifting has anything to do with what actually happened. The towering pallets swiftly accelerated out of the back of the plane, and bumping and skipping, quickly shrank into black dots from our perspective in the plane. Luckily, we too were not forced to “drift”, but deplaned after the aircraft stopped.

The site that greeted our eyes was quite unique. Thirty or more people stood out in the snowy oblivion, waving and shouting cheerfully. Behind them, a neat row of 23 flags marched south, representing all the countries participating in the project. This is NEEM camp’s main street. On either side were the rows of red domes and Jane’s ways that comprise the sleeping quarters. At the far end of camp rose the giant black geodesic dome, which is the center of camp life, complete with a fully equipped kitchen, indoor bathroom and shower, foosball table, movie projector, computers, printers, and a kegerator. Conspicuously missing was the place where all the science takes place. Soon I learned that just a small white tent marked its surface expression, and that the drilling, logging, and processing all took place in a labyrinth of underground tunnels and chambers, dug into the very snow we’d come to study.

That first day was devoted to rest and relaxation—and staying out of the way of the reporters who were scrambling to conduct interviews, get the perfect shot, and stay warm during the 5 hours they had before the C-130 returned from Thule to take them home. With a lot of luck and just a bit of rearranging, the reporters came just in time to see the piece of ice that contained the transition from the last glacial period to the present interglacial. This is easy to spot in the ice for several reasons. First, cloudy bands visible to the naked eye begin to appear for the first time. These are dusty layers deposited on the surface of the ice sheet 11,000 years ago or more. During the last glacial period, many parts of the world were dryer and sea level was lower, increasing the supply of particles small enough to be transported by wind. Another way to identify this point is through the ECM, or Electrical Conductivity Measurement, which is the machine I am operating during my time h
ere.

The process basically consists of dragging a pair of electrodes down a clean surface of ice. The strength of the current generated between the two electrodes depends on the amount of impurities in the ice. Counterintuitively, although the glacial period was dustier, there was also a much higher supply of calcium ions. These neutralize the negatively charged ions in the ice and cause the ECM signal to decrease dramatically. Therefore, the shift from glacial to interglacial is evident in the ECM record as a drop in voltage by a factor of 100!

Yesterday was our first full day of work, and it was slow going as everyone learned their new tasks. Today was faster and I am sure we will be a well-oiled machine in no time. The basic sequence of events is this: the ice is drilled, retrieved, and logged in the drilline trench, then stored for a few days to relax. After that, it is brought into the science trench where the processing takes place. The core is now in 165 cm sections. First, the core is cut long ways into three pieces, a thin top section, another slightly thicker section, and the bottom half. The top piece then gets divided lengthwise in two. One gets further subsampled and stored for detailed oxygen isotope analysis which will happen later. The other is used for physical properties, which is done at the other end of the science trench. This consists of looking a thin section of ice under cross polarizing lenses, and measuring the size, orientation, and character of the ice crystals.

The middle piece goes to the line scanner, which is the most interesting machine at the moment, as we get into glacial ice for the first time. This piece is flat on both the top and the bottom, and these surfaces are shaved clean until all the saw marks are gone and the ice is perfectly clear. Then it is placed in a machine that drags a camera and a light along the length of the core and takes pictures of the reflected light. Using this apparatus, it is especially easy to see the cloudy bands unique to the glacial climate. After it is finished, it goes back to a saw, where it is divided in half. One half goes to the Continuous Flow Analysis, or CFA, and the other is reserved for the scientific steering committee, who can decide how best to use it in the future. The CFA is an extremely complicated set of instruments that, as the name implies, melt a the ice continuously and measure all sorts of things from ion and trace element concentrations to methane at very high resolution
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The bottom half goes to the ECM. First, I polish the top of the core in the same manner as the line scanner, and then pull the electrodes down the ice measuring the current. With the exception of the transition from cold to warm climates, the ECM is fairly uneventful. However, yesterday we found evidence for 3 possible volcanic eruptions recorded in the ice. These are huge peaks in the conductivity, caused by the volcanic material trapped in the snow. Most of these peaks were accompanied by visible bands of cloudy or dirty ice, and require additional subsampling for tephra analysis. If we can identify the eruption responsible for each band, and if these eruptions are well dated elsewhere (such as where the eruption occurred), tephra layers provide important time markers for us to use when we assign dates to each layer of ice.

After the ECM, the bottom chunk of ice is divided into two sections, the gas piece and the main archive. As implied by the name, the archive is saved. The gas piece is divided up according to a complex plan worked out by all the collaborating scientists who will analyze the air trapped in bubbles in the ice. Then, at the “post office”, we log and package each piece of ice and put it in the appropriate box. There are more than 10 laboratories participating in the gas component of the NEEM ice core, including OSU, so this task can be a little overwhelming!

However, it is four in the afternoon on a Saturday, which means it’s the weekend. We stop work early today, eat a big dinner cooked by volunteers, and then have a raging party. I have heard rumors that they often last until 4 or 5 in the morning, which makes sense since it never gets dark and we don’t have to work until 1 in the afternoon, after brunch, on Sunday. I’ll leave the description of the big event to another night. Skol!

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