Archive for the ‘Uncategorized’ Category

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Rothera: Home away from home

January 4, 2019

During our trip, we were lucky enough to stay at the Rothera Research Station located on Adelaide Island, Antarctica—in the western part of the Antarctic Peninsula, and only a 2-hour flight away from our two study sites. The population of Rothera ranges from around 25 people in the winter to over 100 in the summer. This year they are planning to have ~140 at the peak due to the construction of a new wharf. The benefit to being such a small station is the tight knit community of people at the base, who are welcoming and friendly to newcomers such as ourselves. We could not have felt more at home, except, perhaps, at home.

When we were not training or working there were many recreational activities to take part in such as walking around “The Point,” a nature trail which encircles the island, providing an excellent tour of the local wildlife and a stellar view of sculptured icebergs in the surrounding water. The final stop on the 2-kilometer walk is a cozy bench at the top of the hill above the base, giving a breathtaking view of the whole Adelaide Island and other islands and glaciers in Marguerite Bay. Additional adventures included a large part of the island flagged as safe for exploring, after some basic safety measures like signing a check out sheet and bringing a radio. It is even possible to do some downhill skiing and snowboarding facilitated by being pulled by a skidoo to the top of the slope, similar to a tow rope at the ski resort. While “the Ramp” is the closest slope to the station and perfect for some short laps, one can also make the trek to “Vals,” a flagged downhill area located a few miles from the station in the proximity of the “Caboose” (a small shelter one can retreat to and warm up with some tea). The settings are magical with high peaks, glaciers, ocean, and floating icebergs. For exercise, you can take a jog along the runway after flights are done for the day. Indoor activities include movie nights, yoga classes, trivia competitions, intense board game playing, or hanging out at the bar.

Rothera’s kitchen staff serves up to five filling meals a day including the normal breakfast, lunch, and dinner, as well as two “Smoko” breaks—Smoko refers to “smoke and a cookie,” but the breaks are more like extra Hobbit meals—elevensies and dinner, before supper. These breaks are necessary for the people who work long, physical days out in the cold, but also provide a great way to socialize. Crossword puzzles are popular at Smoko and lunch, where you work with your table to solve clues. Each Saturday night you attend dinner in nicer, non-work clothes and can bring drinks down from the bar into the dining room. We were more or less the only Americans on base, so we were surprised and delighted when the chefs at Rothera put on a full-fledged traditional Thanksgiving meal with all the fixings, along with American and Colorado flags tacked up around the room! We dug in with gusto, and helped our hosts with the nuances of the proper application of cranberry sauce and gravy.

Traveling to Antarctica in itself is a grand adventure as we hope you have seen through the earlier blog posts. It can often feel overwhelming and isolating as you have to constantly adapt to new settings and new people week by week. However, with a base like Rothera, you never feel too far away from home.

A big thanks from Sledge India to everyone at Rothera for helping us every step of the way—from a friendly smile or a word of encouragement to assistance moving our 4000 kilos of gear. We appreciate you all!

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This view overlooks Rothera from the top of the Ramp. Credit: Clément Miège

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While walking around the point, some friendly penguins and an elephant seal appear. Credit: Clément Miège

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Lynn, Clem, and Rachel come over a hill while walking around the point. Credit: Bruce Wallin

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Bruce snowboards on a sunny Sunday afternoon at Vals. Credit: Bruce Wallin

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Lynn releases a radiosonde, which is done every morning on base as part of the meteorology observations. Credit: Lynn Montgomery

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An impressive spread for Thanksgiving dinner hangs on the wall (top left); Bruce, Ted, and Lynn are very thankful about the dinner after a long day of training (top right); this is a typical Smoko meal (bottom left); and some state flags hang in the dining room (bottom right). Credit: Ted Scambos and Lynn Montgomery

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We found water!

January 3, 2019

One of our main science objectives was to confirm the existence and persistence of meltwater in the firn at two ice shelf sites. For the Wilkins Ice Shelf, the remote sensing microwave data combined with airborne radar profiles showed very clear evidence of water. For the George VI Ice Shelf, the available data was not as convincing—at best, we hoped for a few thin layers of wet firn. To examine the snow and firn layering first-hand, we used a lightweight thermal ring drill specifically made for extracting narrow cores of ice and snow at the melting point. This is more accurate than using a dousing rod.

In a nutshell, the thermal drill is an electrical heat ring attached at the end of a long narrow metal barrel. The drill melts an annulus of firn or ice around the extracted core, which slowly rides up into the barrel as the hot ring progresses through the snow, one meter at a time. Core dogs, or small sharp metal teeth just above the heat ring, bite into the core and break it off as the drill is pulled back up to the surface. The barrel is attached to a Kevlar-reinforced cable that includes electric power wires for the heat ring. At the surface, the cable goes through a wheel on top of a tripod to facilitate raising and lowering the drill and keeping it plumb.

The morning after our arrival at the Wilkins Ice Shelf site, we set up the drill and started working. In the photos below, you can see the different steps we took for coring and processing the core. After drilling for a meter in the borehole and breaking the core free from the bottom, we pulled the drill barrel back to the surface and laid it on its side, using magnets to prevent the metal core dogs from catching the core. As we tilted the barrel, the core slide out on to a measurement table, a board for photographing and cutting the core. Once the core was on the tray table, it was cut into ~20 centimeter sections. Each section was measured for its length and diameter, and then weighed. We also described the stratigraphy and measured the thickness of each ice layer. For the very top part of the core (in our case, the upper meter and a half), the density was difficult to measure accurately because the snow core was fragile enough to compact during the drilling process. We dug a snowpit next to the borehole and measured the density of this uppermost section using a snow-density kit.

On our first drilling day, we reached about 10 meters depth and were still waiting for our first signs of water trapped in the firn. We were anticipating the water table to be near 15 meters from the airborne radar data, so there was still a way to go. But on the morning of the second day, at about 13.5 meters depth, we pulled a drill core back up and saw the barrel dripping water. Hurray!! Almost exactly where we predicted, and in complete agreement with the satellite and airborne estimates. We drilled a few more meters in the evening to confirm our finding and happily celebrated over a nice dinner in the clam tent.

We carried on drilling over the next days and to about 30 meters, we started pulling out cores made only of ice indicating that we were below the firn aquifer. We stopped drilling at about 35 meters. Following the drilling we spent a full day on hydrology measurements to characterize the firn aquifer’s physical properties, such as its permeability (using slug and pumping tests) and lateral flow using a salt dilution method.

The last step was to drop a string of temperature sensors into the borehole in order to closely monitor the thermal state of the firn for the next 3 years or so. We said good-bye to the thermistor string, and used fresh fine grain snow to backfill the borehole.

On December 12, we packed up our Wilkins camp and flew to the George VI Ice Shelf site. There, we did not anticipate much of an aquifer which was confirmed by our drilling efforts. We did a similar 35-meter hole and the borehole remained dry and cold with fewer ice lenses. Two notable half meter thick ones at about 10.5 and 30 meters showed up as reflections in the radar profile as well. The drilling was more complicated at this site since the thermal drill was mainly made to drill in warm ice and water, creating a good thermal contact. We did some repairs halfway through the drilling to replace the heat ring as the heating element had burned on the first ring. It was a short day of repair and the new heat ring performed well. We finished drilling to 35 meters and dropped another string of temperature sensors similar to Wilkins to be able to compare the two sites.

Once back at the University (both University of Colorado Boulder and University of Washington in Seattle), we will spend the coming weeks transcribing our notes, processing the firn and ice core data, and analyzing the hydrology data. After flying north from Rothera on December 20, we look forward to sharing our results with our colleagues.

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This photograph shows the drilling and core processing pit. Note that the wind break was not very useful with the wind blowing in the opposite direction. Credit: Ted Scambos

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The drill barrel is back at the surface after collecting an 80-centimeter firn core at about 20 meter depth. Notice the break in the ice core that is hanging at the bottom of the barrel. Credit: Ted Scambos

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The next step is to get the core out of the barrel, for that we used magnets to release the “core dogs” (two little metal teeth that break the core) and the core slides out of the barrel. Credit: Ted Scambos

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Lynn is cutting a core section and will be measuring its dimensions and weighing it. In the meantime, Bruce takes careful notes. Credit: Ted Scambos

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For the first one and a half meters, the core sections mainly made of snow were too fragile to be measured accurately. Therefore, we dug a snow pit and collected snow-density measurements using triangle-shape snow cutters with a 10 centimeter resolution. Lynn is showing one of her a perfect cuts. Credit: Ted Scambos

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It was not always a smooth ride for the drill. In this photo, we are in the process of replacing the heat ring. Credit: Ted Scambos

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After we drilled the borehole, we performed various hydrological tests. For one of them, we added, at the surface, a saline solution that once mixed in the borehole was used as a proxy to quantify lateral flow in the aquifer’s water. Credit: Ted Scambos

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We used a plumbing-type camera called SeeSnake to inspect the borehole. In the photo collage there are a few snapshots of what we recorded at different depths, from the surface down to about 20 meters. Credit: Ted Scambos

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Happily posing with freshly collected cores! Credit: Ted Scambos

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Out to the ice

January 2, 2019

Now fully trained and eager to go, we waited and waited. Weather at our first site alternated between foggy and misty and snowy. But the British Antarctic Survey (BAS) base at Rothera is a bustling place, lots of work and play as well. The team took hikes around the small peninsula, skiing trips, and participated in Quiz Night at the Rothera lounge, part pub and part living room for the entire Rothera staff.

After a week of waiting for suitable weather on the Wilkins Ice Shelf, we made an attempt to fly out on November 30, but to no avail. Conditions remained cloudy at the site and our lead-off team (Tom, our BAS mountaineer, and Clément) camped for the next three nights at Fossil Bluff, a small base that BAS uses as a fueling station and staging area. Finally, on December 3, conditions warranted another try, and we arrived mid-afternoon at the selected spot. Camp setup is always a very full day, but by late evening we had the main tents up and the many cases of gear and tools ordered and aligned with the wind to reduce snow drifting. The next eight days were all about assembling, surveying, and drilling.

Our camp was comfortable, even spacious by deep Antarctic field standards, with a kitchen/work Endurance tent (nicknamed a ‘clam’ tent by BAS), a small outhouse tent, and our reliable Scott tents, the pyramid-shaped tent that was designed by the early British expeditions and is still used by many of the Antarctic programs across the continent. The Scott tent design is all about surviving intense storms and cold – strong side poles and a pyramid shape stand up to even 100 mph winds, and a double wall design and dark coloring make it surprisingly warm, even short sleeve comfortable on a sunny day. The Clam is the hub of the camp, where we cook, meet, and plan. One end is devoted to the kitchen and food storage, and the other end is for sitting, and gear such as backpacks, computers, and radios. The Scott tents were used as sleeping quarters, although one of them had a back-up kitchen in case of severe storms. The BAS “P-bag” (Personal bag) is a sleep kit that includes some real luxury items – foam pad, air mattress, and even a sheepskin to lay beneath a down sleeping bag, and plenty of additional options (sleeping bag liner, bivvy sack, camp down booties) for staying warm and comfy.

The science work in the two camps (December 3 to 11, Wilkins Ice Shelf, and December 12 to 17, the George VI Ice Shelf) centered on drilling and logging ice cores of snow and firn layers, assembling and raising the AMIGOS towers, and traversing the area to gather radio echo-sounding profiles of the snow and firn layering. Each of these goals contributes to assessing the presence of firn aquifers at the sites and the climate conditions that lead to them. We will discuss the drilling in the next blog entry.

Building the AMIGOS required assembling a lot of hardware and the tower, a 25-foot aluminum truss that will hold all the instruments high above the snow surface for several years. The AMIGOS is an automated observing station designed for the snow and ice, with an all-in-one weather station, a snow brightness sensor (sensitive to when the surface of the snow is melted), snow height indicator for measuring snowfall that will eventually bury the station, GPS for precisely measuring the ice movement, a camera for imaging the snow and sky conditions, and a long thermistor string running from the top of the tower to over 100 feet below the snow surface. As the tower is buried, the thermistors will provide a record of how the snow temperature changes. Since a firn aquifer indicates a lot of melting, and large changes in the temperature profile of the deeper snow, the thermistor string is one of the most important tools for understanding the evolution of the water-logged snow layer as time progresses. The AMIGOS stations record collected data internally, and can send most of the data using a satellite phone system (Iridium).

Assembling the tower, including the solar panels and instruments, and tacking down the cabling, required nearly six days at our first site, but having solved many little glitches, and with the experience of going through the process, we finished the second tower in just three days. Raising the AMIGOS towers was a challenge: the upper part of the weather station, weighing 150 pounds, had to be lifted carefully to stand the tower upright. We came up with a plan to use a long ladder as a crane, and Tom designed a rope and pulley system to lift the tower into place. We then secured the tower with three guy wires attached to boards buried deep within the snow.

With the towers up and secure, our attention turned towards mapping the layering in the region with the radio-echo-sounder system, called a ground-penetrating radar (GPR). Our grids around the two sites covered rectangular regions a few kilometers across, to provide an idea of how water and ice layers varied in the regions. Layers in the upper twenty meters indicate ice and denser snow within the pack.

The towers will stay above the surface, running on solar power and batteries, until they are completely buried in about three years. A follow-up trip will visit them just before they disappear to get the data chip and make further measurements, and recover any parts still accessible above the snow.

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This photograph shows part of the tent camp and science gear at Wilkins Ice Shelf. Credit: Clément Miège

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Here is a collage of the camp tents, inside and out. Upper left, the Clam tent; upper right, the latrine tent; middle left, the kitchen area inside the Clam tent; middle right, sitting area of the Clam tent; lower left, the two-person Scott tent; lower right, inside the Scott tent. Credit: Ted Scambos

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This collage shows the AMIGOS tower (right) and some of the sensors mounted on the system (left). From top left, GPS and Iridium antenna; snow height sensor and snow brightness sensor; weather unit; camera and the base of the control box. Credit: Ted Scambos

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Clem and Tom finish the set-up for raising the AMIGOS tower (left) using a ladder (right) and rope and pulley system (not shown). The tripod supporting the drill is in the center, above the borehole that will hold the thermistor string once the AMIGOS is erected. Credit: Ted Scambos

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The Ground Penetrating Radar (GPR) profiling system is attached to a sled behind the snowmobile. Credit: Ted Scambos

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This Ground Penetrating Radar (GPR) profile was collected at 250 MHz near the George VI Ice Shelf site. The echogram data represent about 600 meters across the snow surface. Units left to right on the plot are seconds of time. The sled was stationary for about 75 seconds before traveling 600 meters, and then stationary at the end of the profile for about 50 seconds. A thick ice layer is shown at about 10.4 meters depth, which was also noted in the George VI ice core. Credit: Ted Scambos

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Bruce is sealing the battery box to prevent meltwater leaking into it, prior to burying the batteries and other components. Credit: Ted Scambos

 

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Polar training wheels

November 27, 2018

On November 21, a Dash-7 airplane from the British Antarctic Survey (BAS) was awaiting us on the tarmac of the Punta Arenas International Airport, shiny and electric orange in color, the color of high visibility in Antarctica. We boarded around 10 am for the four-hour flight to Rothera Station. The Dash-7 is a remarkably versatile aircraft, four engines and a high wing, capable of carrying about 8,000 pounds. For BAS, it is configured as a mix of a cargo and passenger plane—gear was strapped to the bare front half of the plane, while sixteen airline seats stretched in the back. A coffee station and tiny bathroom in the back made the flight more comfortable. After three hours of smooth conditions, the first icebergs and a distant mountain view of the Peninsula appeared.

After landing and stepping into a sterilization pan for sanitizing our boots (to avoid contaminating Antarctic soil), we were warmly greeted by the station manager, Dave, and our field guide, Tom Lawfield. A brief walk to the main building (called New Bransfield House or NBH) followed, for introduction slides and a cup of tea. Tom gave us the training schedule, a series of modules set at a fast pace that will keep us busy for the next three or four days—everything from weather training to snowmobile driving, and lots of safety briefings on first aide, crevasses, survival, and how to use the renowned Primus stove and Tilley lamp in the tents. The design has not changed much since the days of Scott and Shackleton, because they work so well.

Most buildings here are named for dog-sledding teams from earlier pre-BAS expeditions when dogs were still allowed on the continent. In the 1980s and early 1990s, after some concerns about dogs possibly running off and even surviving in the wild, the last Antarctic groups with dog teams gave up the practice. Lynn is staying over at the Admirals building, while Ted, Bruce, and Clem are sleeping at Vikings, a newly-assembled building made of about eight pre-fabricated shipping containers put together in a neat way to provide nice, clean, and cozy sleeping accommodation. After settling into our rooms, we headed over to NBH for dinner and got a first taste of the fantastic hospitality from our British hosts.

Our following days were made of various training modules that are required before heading into remote field sites. We started off with a set of short lectures on airplane procedures and safety, how to take accurate field weather observations, where the various support groups were on the base, and rules to follow while here. We also visited the station doctor to get familiar with our medical kit that will accompany us to the field. The afternoons involved outdoor training modules such as mountaineering 101, crevasse rescue, snowmobiles 101, and linked-snowmobile travel for uncertain terrain. Another module was “campcraft,” where we got the chance to spend one night outdoor, practicing setting up our pyramid tents and digging emergency snow trenches in case we got caught in a blizzard unable to find our tent. We learned it is best to anchor down instead of proceeding further and getting more lost.

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Clem plays with his ice axe while Tom is pulling out his crampons as part of the mountaineering 101 module. Credit: Lynn Montgomery

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On a sunny afternoon, Ted and Bruce are doing their best to stop Lynn and Clem from falling simultaneously into a crevasse. Credit: Ted Scambos

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From the crevasse perspective, Lynn and Clem appear safe, but they were scared by what just happened. Thankfully their falls have been stopped. Credit: Ted Scambos

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Ted inspects the roof of his snow grave to make sure it will give him sufficient protection from the blizzard. Credit: Ted Scambos

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On the last day, Bruce and Tom are practicing the linked snowmobile travel that we will use while in the field to collect the ground radar data. Credit: Clément Miège

Once the training period was over, we could dedicate two days to prepare our science equipment and get our science cargo ready for the put-in flight. A lot of time was devoted to updating the AMIGOS stations from past sites and working with the sensor systems selected for Firn Aquifers. We have been lucky that our field guide Tom got all our camp equipment ready well before we arrived in Rothera. Thank you, Tom!

The few photos below illustrate critical moments as we are getting our science gear ready for deployment into the field.

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On the deck of Old Bransfield House, Bruce tests the data-transmission module of the AMIGOS station. The AMIGOS stations have a long history in the Antarctic Peninsula research work, with the acronym standing for Automated Meterology-Ice-Geophysics Observing System. Credit: Ted Scambos

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Lynn carefully applies a thin coat of solder on each of the thermistor wires to prevent the stranded wires from coming apart. Credit: Ted Scambos

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One of our last science preparation tasks consisted in testing a phase-sensitive radar in our office to see if we could get a signal transmitted and recorded by the computer. Ted is happily taking apart the receiving antenna after successful testing. Credit: Clément Miège

This takes us to November 26, which was our first put-in day. Unfortunately, the weather was not cooperating and we have been on hold since, ready to go once the sun shines on the Wilkins.

Finally, we wanted to add a short biography of Tom Lawfield, our field guide, which will be responsible for our safety and managing our camp while in the field.

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Tom Lawfield. Credit: Ted Scambos

I am a Field Guide with the British Antarctic Survey, based at Rothera Research Station on the Antarctic Peninsula. Day to day, I may be delivering training for glacial travel and field living, assisting deep field research projects within British Antarctic Territory (BAT), or running operations at a deep field runway such as Sky Blu. My work usually involves a fair amount of shoveling snow. When not in Antarctica, I run expeditions, skiing and climbing courses in the UK and worldwide. I have an MA in Environmental Security from the UN mandated University for Peace in Costa Rica, and an MPhil (Cantab) in International Relations, where I was interested in the link between climate change and security. Read more about my life and work at Rothera here.

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Moving south, part 1: The lone stars

November 17, 2018

The Firn Aquifer team took a giant leap southward on November 12 to 13, flying through two places that share almost identical flags—Texas and Chile. In fact, the Chilean design (with a shrunken blue area on the upper left) came first, in 1817—and is known in Chile as La Estrella Solida, the lone star. The Texan flag was first used in 1839 by the early Republic of Texas, and then re-adopted by the state in 1933.

The Firn Aquifers team scrambled to get equipment ready and shipped following a late approval for the trip from the National Science Foundation (NSF) in mid-August. We had to rebuild two recovered weather stations to be re-used in the study, test and ship the ground-penetrating radar system, send the ice-core drill, generators, solar panels, food, field gear, and completely equip ourselves to measure the aquifer if we found one—about 1600 pounds of gear. Inevitably, some things were not ready in time to ship, so we had to carry large black footlockers full of instruments, wires, and data loggers. The team showed up at the Seattle and Denver airports with nine bags among four travelers, including six laptop computers (two computers were already shipped) with varying levels of polar invulnerability—one of them a truly monstrous Panasonic Toughbook that included enough steel to armor-plate a Humvee, should the need arise. This thing has its own gravitational field.

The critical items were seven large lithium batteries. As any STEM researcher who travels can tell you, moving lithium batteries is like moving people’s party affiliation—it does not happen easily, and often returns to its origins. Among the rules, lithium batteries cannot fly as cargo if the plane also carries passengers. On cargo-only flights the batteries must be specially packed as hazardous cargo. However, there are no cargo-only flights in Patagonia. After much debate and fretting by our Antarctic Support Contractors, Leidos, and realization of the truly incomprehensible rules for lithium batteries on an international journey, we realized that our best hope was to carry them on the plane in our personal bags. A risk. Although perfectly within the rules, one overcautious TSA person could end the radar aspects of the work. Thankfully, we had no issues, and one of our last concerns about gear and science readiness was solved. We arrived in Punta Arenas, Chile on the afternoon of November 13, and hit a favorite restaurant for a delicious local seafood dinner.

Over the next few days, we plan to get fitted for polar gear, check our cargo, and rest until we take off for Rothera, Antarctica. Stay tuned for more info!

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Antarctic firn aquifers: the team

November 16, 2018

 

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Ted Scambos

Ted Scambos is a senior research scientist at the Earth Science Observation Center, a part of the University of Colorado Boulder; and Principal Investigator on the Firn Aquifer grant. Ted’s research covers many aspects of polar science and climate change, using satellite data to track the ice and how it is evolving over time and under a changing climate. The Firn Aquifers expedition represents his 19th trip to Antarctica, but the first to this region southwest of the Antarctic Peninsula. Ted and Kari live in Lafayette Colorado, and enjoy gardening, winemaking, skiing, and hiking.

 

 

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Julie Miller

Julie Miller is a postdoctoral research scientist at the Earth Science Observation Center; and Co-Investigator on the Firn Aquifer grant. Julie’s research focuses on developing innovative techniques to map surface and subsurface ice sheet properties using airborne and spaceborne microwave instruments. She is currently developing new techniques to map firn aquifers in both Greenland and Antarctica. Previous fieldwork has taken her on instrument deployments to Greenland and the Canadian Arctic. This would have been her first expedition to Antarctica; however, a last minute injury forced her to sit this one out. Julie will provide support for the team from her home in the mountains of Utah.

 

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Clément Miège

Clément Miège is a postdoctoral research scientist affiliated with the Department of Geography at Rutgers University, but he lives and works in Seattle, working remotely from the University of Washington. His research focuses on combining ground, airborne and satellite observations to further understand snow and firn processes taking place on ice sheets and glaciers. Past fieldwork has taken him mainly to the Arctic, so he is really looking forward to going to Antarctica this time! In their free time, Clem, Michelle and little Elise enjoy exploring the endless nature the Pacific Northwest has to offer by foot, bike or ski.

 

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Bruce Wallin

Bruce Wallin is a research scientist and software developer at the National Snow and Ice Data Center at the University of Colorado Boulder. His background is in statistics and software engineering and he brings a diverse technical skill-set to bear on the challenges of monitoring and understanding the frozen regions of the Earth. This is not only Bruce’s first expedition to Antarctica, but indeed first trip to the field and he is thrilled to be involved. Bruce, girlfriend Zhixing, and border collie Dundee like to spend their free time in nature hiking, rock climbing, and disturbing wildlife with campfire songs.

 

 

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Lynn Montgomery

Lynn Montgomery is a second year graduate student in the Atmospheric and Oceanic Science program at the University of Colorado Boulder. Her research focuses on surface mass balance processes of the Arctic and Antarctic. She spent two field seasons in 2015 analyzing a firn aquifer in Southeast Greenland and is excited to investigate the possibility of firn aquifers in Antarctica! In her free time she enjoys hiking, trivia, and watching The Price is Right with her fiancé Brennan and two cats, Lily and Oscar.

 

 

 

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Terry Haran

Terry Haran is an associate scientist who retired January 1, 2018 after twenty years at the National Snow and Ice Data Center and 5 field trips to Antarctica. He helped develop the software contained in the two Automated Meteorological Ice Geophysics Observation Systems (AMIGOS) units that the Firn Aquifers field team will be deploying on the Wilkins and George VI ice shelves. He was called back out of retirement in August 2018 to help in refurbishing the AMIGOS units, and will be staying in Boulder during the Firn Aquifer field deployments. Terry will help monitor each unit’s health and data collection remotely by way of the Iridium satellite communications system built into each AMIGOS unit.

 

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Hi Again from the Scar Inlet Camp

February 23, 2016

Ted Scambos writes:

In the first two weeks out here, we’ve set up an array of measurement instruments to observe how the ocean ice (‘fast’ ice near the coast) and the much thicker ice shelf ice behave at the end of the summer. In past years, this has been the time of year when major changes, and even ice shelf collapse, have occurred. The weather has turned cooler, and it is unlikely the ice will break out this year, but the instrumentation we have brought, and the long steady data acquisition we’ve had since we set up the instruments, has yielded some interesting results.

One of the main instruments we set out are time-lapse cameras. The idea here is of course to detect changes in the ice fracture patterns, and any movement of the icebergs that are the breaking away from the ice shelf. We have set out six camera systems, as two stereo pairs (for 3-D data) and as ‘eagle eye’ systems looking at the most active features. The pre-installed AMIGOS-6 system has been watching the area 4 times a day for the past 4 years, but we’ve set up much faster systems now to catch a movie-like view of the changes, with 2-minute repeats of each scene. Sure enough, during some wind-storms we’ve seen the fast ice fractures move a bit, straining as many square miles of rough ocean ice surface are pushed by the wind. Satellite pictures tell us that the biggest wind-storm (gusts to ~40 kts, or around 20 m/sec) pushed the loose sea ice to the east of us about 3 kilometers… but the fast ice here held.
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Time-lapse cameras watch the fast ice, icebergs, and ice shelf junction area from the outcrop we call ‘Pippa’s Point’. The cameras have been taking pictures every two minutes for ~15 days.

We have a more sensitive way of looking at ice motion: a radar system. This radar array (the Gamma Portable Radar Interferometer, or GPRI) collects data sets that can be very sensitively differenced from one another, to detect even millimeters of movement. This is the instrument we anticipate will tell us the most about the state of the ice in this area, and may provide clues as to how much the fast ice is buttressing the ice shelf and inhibiting its break-up (or ‘calving’ in glaciology terms). We may see a tidal signal of ice movement and fracture, and it appears that we’ve captured smaller versions of the ice shelf collapse process in some of the icebergs close to the system. The team has worked extremely hard to keep this high-tech instrument going in the conditions of a deep field tent camp, but it has paid off in several terabytes of data. Early processing here in the field shows that we’ve captured the movement of the ice well, and have data extending out to about 8 km.

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Chris Carr and ‘Chucky’ Stevens assemble the radar interferometer at ‘AMIGOS Point’.

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Chris adjusts the data cable for the radar array.

A much simpler ‘radar’ system, really more of a radio-echo sounder, was used to map the ice thickness over the cape. It looks like our cape is actually an island: the neck of ice that extends out from the main coastline appears to rest on rock that is below sea level. If the area were to melt away completely, this would change the local currents.
radio_echo_sounder

The radio-echo-sounder measured a profile of the the ice thickness at Cape Disappointment.

Other sensors aim to use sound and vibration as an indicator of processes going on in the area. We set up an array of special very-low-frequency microphones (an ‘infra-sound array’) on one outcrop of rock to listen to the deep sounds of cracking and grinding going on in the ice – like the deeper notes of thunder, these can travel many miles. The network of microphones allows us to locate the source of the sounds. The majority will come from the shifting sea ice blocks, but a few will likely come from the large ice shelf bergs. We’ve also paired this through-the-air vibration measurement system with three wide-spectrum seismometers to record the larger vibrations as they travel through the earth.
infrasound_array

Dr. Erin Pettit adjusts the the infrasound array. Thin orange cables go out to several microphones located 10 to 100 meters away. The orange box on the left is a seismometer.

We are even listening to the water. After some careful scouting, our field guide found a path where we could safely approach the water’s edge several hundred feet below our field camp and install a hydrophone. This required a technical climb down a steep crumbling slope (which we’ve dubbed ‘Chucky’s Challenge’ after our intrepid BAS field guide). But this too paid off with several 2-minute data ‘takes’ of the ocean sonic environment. Erin put some of the data on a small speaker one evening after our dinner. It was haunting – booms and bangs and strange squeaks, and a constant background hum of tiny bubbles popping as the ice slowly melts.

chuckys_challenge

Christina Carr (blue jacket) helps with the ropes as Chucky Stevens lowers himself to the ice-covered water. A small crack near the shoreline allowed us to place a hydrophone into the ocean.

We brought one more instrument with us that was intended to be used if a truly spectacular break-up were in progress – a camera system mounted onto a tethered helium-filled balloon (or ‘aerostat’). With a set of tiny cameras looking in all directions, the balloon can provide a continuous panorama of events in the ice for up to 24 hours. We decided to test the system for just a few hours one evening, and learn more about how to manage it for other projects.

balloon_deployment

Set-up for the balloon deployment. Left, Erin indicates the expected direction of the flight. Right,Ted completes the set-up of the camera system just before deployment.

balloon_images

Images from Camera 1 on the balloon system. A hand-held GPS is mounted to the payload to record time and elevation during the flight (and records the latitude and longitude internally). Top left, image from ~25 feet above the surface (1013 feet above sea level), showing Erin and Ted, with Chucky at the balloon winch. Top right, image of our camp from approximately 180 feet above. Lower left, a picture of ‘Pippa’s Point (left outcrop) and ‘AMIGOS Point’ (right outcrop) from an elevation of 1000 feet above camp. Lower right, an image of some of the outcrops north of our camp from an altitude of 4674 feet above sea level.

Our work now is mostly managing our instruments, making sure the data acquired are good, and creating back-up copies of what we collect. Soon we will begin to pack up the gear and begin our return to Rothera and then South America. We are now the very last science team still out in the field in the British Antarctic Survey network… and it is getting dark every night. It is time to leave, before the Antarctic winter takes hold.

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