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Archive for the ‘Summit Station’ Category

Last summer, just before IGERT cohort 3 journeyed up to Summit Camp, the Greenland ice sheet experienced extensive surface melting. Much of the top layer of snow melted and dripped through the snow near the surface. But of course in the cold weather, it didn’t remain as water for very long! This water refroze in the snow, forming flat layers of ice which are connected to one another by vertical columns of ice (see the picture below for an idea of what this looks like). Since last summer, it has snowed quite a bit at Summit, so now the ice layers and the columns that connect them are buried. We would like to know what this ice layer looks like and how many of these ice columns formed in areas around Summit Camp. Now don’t get me wrong, I love digging a good snow pit, but unfortunately, we can’t dig up miles of snow. What we would like is to see what’s under the snow without having to break our backs.

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A view inside of our snow pit. I am pointing to the vertical ice column which is right beneath an ice layer that extends all the way across the snow pit. (Photo: Jim Lever)

Using ground penetrating radar (GPR), we can look down below us and “see” the layers of snow upon which we stand. We can also see when there is something different in the snow, like ice which is visible because it has a much higher density.  In our first week, we have spent some time getting the radar system running and testing it out by setting it in a sled and pulling it behind as we walk. One question lingered – is the radar “seeing” what we would see in real life? For that, we had to dig! We dug up a snow pit to see just how prominent the ice layer actually is and to determine if we could see any vertical ice columns. Sure enough, both the ice layer and even a vertical column were easy to find in the snow pit!

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Walking off into the distance with the ground penetrating radar in tow. (Photo: Jim Lever)

Though pulling sleds wasn’t so bad, I would sometimes sink nearly to my knees in snow drifts which made keeping a constant walking pace tough. Enter Cool Robot – an autonomous robot (designed right at Dartmouth’s Thayer School of Engineering and wired up by IGERTeer Ben Walker!) that can follow preset directions and drive itself in nice, well-paced patterns across the snow while towing the radar system. We set up a square grid for the robot to follow that was 50 meters on each side. The robot is light and reliable – not sinking into the snow, keeping a constant pace and following our directions within about a meter of the set path. So I’ll admit, Cool Robot has me beat by far in the ability to run a GPR survey. But hey, at least I know not to run straight into the flag markers all around camp! : )

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Cool Robot crushing the competition in quality of GPR surveys! (Photo: Jim Lever)

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The first of the IGERTs are up in Greenland as the 2013 field season begins. Ben Walker and I (IGERT cohort 4s) are up at Summit Station in Greenland for the next three and a half weeks with Dr. Jim Lever from CRREL and Alison Morlock (a recent Thayer MS graduate – congrats!). We will be working with the Cool Robot – a solar powered robot that is designed to carry instruments across polar ice sheets for scientific research. I have a few different projects that I’ll be working on up here, and the science is just getting started!

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Spectacular view out of the window of the LC-130 cargo plane! My best guess at a location is Northern Canada!

We had a great trip from Scotia up to Kangerlussuaq on Monday, and only a night in Kanger before heading up to Summit. We still took the time to take a walk around Kanger and up to Lake Ferguson. After the unfortunate washout of the bridge last summer, construction of the bridge across the river in town is moving along, but it is still not complete. We were able to take a route around and over to the lake. We were surprised to find that there was still ice on the lake!

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There was still ice covering most of Lake Ferguson!

We received a very warm welcome from the crews at Kanger and at Summit, and we are so thankful of all they have done for us already! The rest of the week has been spent acclimatizing to the altitude, unpacking and testing out gear and making plans for the rest of our trip. More updates to come!

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View of Summit Camp at bedtime

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Last summer, several IGERT fellows had the serendipitous and rare opportunity to witness a warming climate’s effect on Greenland first-hand. Julia Bradley-Cook was stationed in Kangerlussuaq collecting data on carbon cycling in soil when the bridge over the Watson river collapsed from anomalously high flows of meltwater (see https://dartmouthigert.wordpress.com/2012/07/11/glacial-melt-threatens-town-water-supply and https://dartmouthigert.wordpress.com/2012/07/11/update-the-river-powers-on). Days later, the 3rd cohort of Dartmouth IGERT students flew up to Summit Camp, Greenland’s highest point, and observed features of the ice sheet-wide surface melt. Fellow Kaitlin Keegan, Thayer Professor Mary Albert, and their collaborators study the frequency of such melt events; their work at the North Greenland Eemian Ice Drilling (NEEM) sight has suggested that such an event last transpired in 1889 and, therefore, is unprecedented in the satellite record. (See https://dartmouthigert.wordpress.com/2012/07/21/new-summit-melt-layer).

A new Nature publication on Greenland climate authored by the NEEM community, which includes Albert and Keegan, prompted an entry on the scientific blog site RealClimate.org. RealClimate was started and is maintained by “working climate scientists” who “aim to provide a quick response to developing stories and provide the context sometimes missing in mainstream commentary.” Check out the discussion on Greenland’s 2012 summer conditions, how they compare to those 125,000 years ago, and what we can learn about past temperatures and sea level rise from an ice core! I was particularly excited about the conclusion of the entry since author Dr. Steig mentioned the significance of a new ice core from West Antarctica. I just returned from a field season on Roosevelt Island assisting with the drilling of this core, which will help scientists understand the sensitivity of the Ross Ice Shelf and, thus, of the West Antarctic ice sheet to changes in climate. http://www.realclimate.org/index.php/archives/2013/01/the-greenland-melt/

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When the C-130 plane touched down on the Greenland Ice Sheet, its landing skis cracked and crushed the icy surface of the ‘ski-way’, jolting passengers from their reveries and their seats. Despite my earplugs and the otherwise-deafening roar of the plane, I could still hear the skis grind through icy, hard-packed snow as we taxied to the field station. We had arrived at the highest point of the Greenland Ice Sheet—3,200 meters above sea level.  Even though conversation was impossible through the noise, the anticipation and excitement of the students and summit crew was palpable. We silently sprung into action putting on our final warm layers, fetching and securing packs and then impatiently glancing and smiling at each other until the plane stopped and the door opened. We stepped out into the freezing, white territory one by one—still in eerie silence due to our ear protection—boots crunching on the snow, walking slowly in the thin air to the “Big House.”

Arriving at Summit Station. Photo by Courtney Hammond.

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Quentin Watson (left), Chef, and Ken Jessen, Camp Manager.

The “Big House” is the center of activity at summit, hosting a large kitchen, numerous tables for congregation, a futon, the manager’s office, and an extremely sunny bathroom (I’ve never needed sunglasses to brush my teeth before). The building sits atop tall, metal stilts, which, on good days, keeps it above winter snowdrifts. When we arrived from our flight, the house was warm and smelled like delicious food—the first of many incredibly tasty meals we would indulge in at summit. After lunch we were given instructions from the camp manager, Ken, about general rules of living/surviving at summit. These rules ranged from making sure to wash hands or use sanitizer before every meal and at every possible opportunity (there was sanitizer conveniently stashed in every corner of camp), to using the highest level of caution and sense at all times, as being evacuated from camp, is, well, highly undesirable and risky. Next, we heard instructions about staying healthy from the medic, Ben, who is a part of the incoming IGERT cohort. After the logistics talks and welcomes adjourned, we were set loose at camp.

“Big House” at Summit. Photo by Courtney Hammond.

It was vast, silent (save for the tractors moving snow during the day), and white-to-grey, depending on the sky. While bamboo flagpoles permeated the immediate area of camp— marking walkways, science equipment, and boundaries—the extent of flat, unadulterated snow past the summit encampment was truly astounding. We had plenty of time to ponder the grandeur of it all while we took turns working inside the pit. To keep warm during our outdoor sampling stints that would last 3-4 hours at a time, we made videos, took pictures, learned a tap dance routine and sometimes trekked back to the big house for a quick cup of tea. The temperature hovered around -18 C throughout our stay, with winds coming and going and the sun ever-present.

July 21, 2012-2

“Walking into the Expanse” by Courtney Hammond.

The transition between nighttime and daytime hours gets blurred at the poles since it is light all the time during summer. However, the temperature was noticeably colder when I would walk across the snowfield to “tent city” at bedtime. Orange tents in perfect rows are set up at one edge of camp, and researchers and students visiting summit sleep there during their stays. Since we were the only researchers visiting at the time, we each had our own palatial “Arctic Oven,” which has a layer of insulation to trap solar energy during the day. Since our first three days at summit were overcast, we did not have such luxury of a toasty tent at night.  My personal sleeping accommodation consisted of a cot, a hot water bottle at the foot of my sleeping bag, a fleece liner, and a -20 F sleeping bag (I may have also put my own zero-degree bag over my cot as extra comfort—psychological comfort, if anything). Between the tent flapping viciously in the wind, the blinding sunlight (it seemed sunnier inside the bright orange tent than out!), the high elevation, and the bitter cold, sleeping did not come naturally to me on the first night at summit. It was my first night sleeping on the Arctic ice ever, and it was all completely foreign—including the choice method of peeing in a water bottle in the middle of the night as alternative to trekking to the outhouse.

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“Tent City”

By the 3rd night, however, I was STOKED. What an amazing, simple, lifestyle. When  ‘home’ is a little arctic hut, and the day’s duties include collecting snow and firn samples with the goal of better understanding the Earth’s past climate, a unique rhythm can set in, both individually and within the group. Upon leaving summit, the only illness I feared I was getting was what our professor, Ross Virginia calls “Arctic Fever”—the need to return year after year after year for this totally unsurpassed feeling of adventure, camaraderie and discovery.

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Excited to be Women in Science. Photo by Courtney Hammond.

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While Steph’s permeability measurements (see the post from July 23) served as our chief scientific focus on the ice given their direct relevance to her dissertation work, they were far from the only in-situ data we collected.  We measured many standard physical properties (stratigraphy, density, temperature, etc.) in the 1.4-meter deep snow pit to gain both practice with field instruments and familiarity with snow properties.  In addition, I elected to take hourly temperature measurements to complement data I am analyzing in my current project.

1) A qualitative look at the pit “stratigraphy” (layering of the snow):

Ali looking at Layers
 Ali and Jess looking at layers of “hoar,” comprised of very coarse and porous grains.

We looked at the snow from top to bottom, observing changes in its appearance and labeling it on a spectrum from coarse to fine.  Steph has experience characterizing snow coarseness from the Antarctic firn cores she analyzes and shared her knowledge with the group.  Lee also conducted a “hardness test” by looking at the relative depths to which she could push a pencil into the snow with the same force.

2) Density: We measured the density of the snow continuously from the surface to the base of the snow pit with a small, sharp metal tool.  We generally expect density to increase with depth (as more and more snow builds up, the underlying snow compacts), but the density values and amount of change vary between sites and times of year.

The metal tool cuts into the snow, leaving a 3-cm high rectangle in the pit wall.  We measured the weight of the extracted snow on a balance and divided that by the known volume of the tool to give density.

Density Measurement
Chelsea handing Lee the density cutter filled with snow, ready for weighing.

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The pit wall with holes left from density measurements.

3) Temperature: Nine thermometers placed in the pit wall provided a temperature profile with depth.  I elected to take regular readings of near-surface snow temperatures in the hope that they could elucidate the source of some variability in Summit temperature data I’ve been analyzing back in Hanover.  Additionally, I was interested in seeing how deeply the daily fluctuations in temperature are “felt” in the snowpack.

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The top five thermometers, spaced at 2, 4.5, 7, 13, and 20 cm from the surface.

Our scientific experiences in the field were complemented by talks that we’d prepared for each other (Mary gave a talk on firn which virtually the entire camp attended!) and interactions with other scientists on base.  One in particular, Kevin Hammonds, is a grad student at the University of Utah and gave us a tour of the “Mobile Science Facility” (MSF) of the Integrated Characterization of Energy, Clouds, Atmospheric state, and Precipitation at Summit (ICECAPS) project for which he is a summer technician.  He showed us the myriad of radar, LiDAR, and microwave instruments and cameras designed for looking at the microstructure of clouds and snowflakes.  Check out the cool pictures from his blog!

Being at a site of both current and past groundbreaking science was humbling in and of itself.  For those of us who study ice and climate, seeing the top of the GISP2 borehole provided a highlight of the trip:

GISP2
The ice core from the Greenland Icesheet Project (GISP2) reaches two miles down to the base of the ice.  It archives over 100,000 years of Earth’s history and has provided much of what we know about climate change today.

Summit provided an ideal classroom for sharing glaciological knowledge; I think we were all bummed that our time there was so short!

Group shot at Summit
The group on the stairs of the “Big House” at Summit Station.

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This post was written by Professor Mary Albert

Our NSF-IGERT studies at Summit, Greenland are designed to investigate aspects of snow, firn, and ice core interpretation, as part of our larger look at polar environmental change in Greenland. Coming to the site of the GISP2 ice core, where ice core scientists first realized that climate could change in less than ten years, is a real adventure for our graduate students! Being here now to witness a new change and to measure its effects  — the first significant melt at this cold high-altitude site since 1889 – is but one of the great opportunities to showcase the excitement of working in polar science!  The National Science Foundation has facilitated this unusual and extremely educational opportunity in this brief round of science here at Summit, the very top of the Greenland Ice Sheet.

Our third-year IGERT student, Kaitlin Keegan, came up earlier to conduct snow science with the JSEP group of high school students; she then left Summit before our arrival to venture on to the NEEM site. I have thoroughly enjoyed the honor of leading the discoveries with our first-year IGERT students – what a bright group of PhD students they are!

IGERT Cohort 3 at Summit
The Dartmouth IGERT group at Summit. From left to right: Mary Albert, Stephanie Gregory, Lee Corbett, Jessica Trout-Haney, Chelsea Vario, Alexandra Giese, and Ian Baker

We made stratigraphy, density, and permeability measurements on important layers in the snow.

Steph and Mary looking at Firn Sample
Stephanie Gregory and Mary Albert discuss a snow sample for a permeability measurement.

We collected samples of the refrozen melt layer to take home for more detailed measurements. Hey, even our panda got a taste of ice science!

Panda eating Ice

Being at Summit immediately after the first big melt there since 1889 has been a great science & education opportunity!  We are all very thankful to the NSF IGERT program for supporting these students, the NSF Office of Polar Programs for allowing us to come to Summit, the Air National Guard for getting us to Greenland, and to all of the wonderful folks at CH2Mhill Polar Services for providing superior field support, including the extremely capable camp staff at Summit Station.  A very hearty Thank You to you all!

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Today’s plan was to spend the morning taking 9 shallow firn cores.  From these cores we would locate a single firn layer present in all nine cores that could be used to help determine the spacial variability in the permeability of a single layer of firn.  Permeability is the measurement of how easily a fluid can flow through a porous medium.  In our case we would be measuring the flow of air through the firn.  The cores had to be at least 2 meters deep (6.5 feet) in order to have firn cores that would not fall into pieces when they were taken out of the ground.  The plan seemed simple: drill 9 shallow cores, find the same layer in all 9 cores, and measure their respective permeabilities.

July 21, 2012-6

Steph drilling the first shallow firn core

Lesson of the day:  In the field, things are never as simple as they seem.  Upon inspecting the hand drill that was onsite we found it was not in working order.  While we were trying to bring the drill back to life the majority of our group did snow pit measurements consisting of stratigraphy, densities, temperature profiles, and hardness.  The snow pit measurements continued until we stopped for lunch.

July 22, 2012-2

Jess and Chelsea taking measurements in the snow pit

While eating our delicious lunch we got the news that the drill was functioning properly (woohoo!).   Our first task after lunch was to drill our first firn core.  The first meter of the core went well.  The second meter of the core went well.  The last meter of the core went well… until we tried to remove it from the ice sheet.  Turns out, it really didn’t want to leave its home.  We tried turning the drill to back it out, tapping it to loosen the connection with the underlying firn and pulling up as hard as we possibly could.  The drill didn’t move an inch.  The method that finally proved successful was to have Courtney and Lee lay on their backs and essentially leg press the drill out of the borehole.  For some fantastic footage of the event check out the video below.

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Courtney and Lee leg pressing the drill to free it

Overall we had a very productive day in the snow pit and an excellent learning experience on how sometimes the field determines the work you can actually do.  The new plan is to determine the spatial variability in the permeability of single snow layer.  No drilling necessary.

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