Posts Tagged ‘Flask’

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Success

November 22, 2010

Ted writes:

Clear weather finally prevailed on the morning of November 18, and after one last check of satellite imagery, we bolted at noon in our 1970s-vintage DeHavilland Twin Otter (with brand-new instruments and engines) off the runway at Rothera, headed for the Larsen Ice Shelf. Aboard were myself, Martin, and Jenn, BAS pilot Doug Cochran, and a BAS staffer named Andy “Boat” Wilson – known as Boat because he is a diver and a boatman for the base, and a sturdy guy to have along.

A few puffs of grey cloud passed by on our way upward, but then gave way to one of the most glorious spectacles in glaciology: the Larsen Ice Shelves and the eastern coast of the Antarctic Peninsula. Spilling ice from the ridge, which sits in the southern storm track building snow, flows down like marshmallow cream through black, jagged peaks, and then spreads out to an impossibly flat, broad sheet of ice. Only the subtlest of rolls and ridges mark the history of the bending that the ice endured to reach the sea.

What we saw confirmed what we’ve learned from the data streaming in from the AMIGOS and other stations. While the west side of the Peninsula has experienced unusual snowfall, the east side, where our stations are, has been bone-dry and very warm all winter. Already there are melt ponds slowly filling, and the dry warm wind has scrubbed the surface down, exposing every crack and ridge.

Our first rendezvous was at the Scar Inlet AMIGOS site. Although the station is still functioning, two of the most important measuring devices have gone silent or intermittent over the winter: weather and ice motion. The camera is still working well for now. But as we circled the site, we realized that the landing last year was something of a miracle: the site is surrounded by dozens of narrow (2-foot wide)
cracks and slots. The pilot circled several times, determined to give us a landing if there was any chance; but the risk of bending a ski on the airplane was too great. We did manage to get several pictures of the site, and in some ways the news is good. The station is still standing, and with the anchors still firmly in place.

We then flew up the first major glacier feeding the Scar Inlet Shelf, Flask Glacier. A second AMIGOS there is working very well, but needed new software and a new snow reflectivity sensor. We use the snow reflectivity to gauge when melting occurs: the snow darkens quite a bit when it is wet. The landing went perfectly; right on the tracks from last year, and Doug pulled the plane right up to the station. The wind was brisk, but warm, right about at freezing. The station has about 70 centimeters of snow around it, but it is an oddity–everywhere around it is evidence of windswept snow surface.

While we were standing there, the camera came to life! It moved to the six set shots that Terry had programmed in months ago. I tried to remember the sequence, and started leaping around in the snow, trying to get in every picture. But the camera was too fast. So, in every one of those pictures, one second later, I’m standing right there smiling. Martin, Mr. Smarty-pants, let the camera come to him, by standing still, and Jenn just shrugged and kept working. Jenn and I opened the station and changed the software chip, while Martin removed the old snow sensor and installed the new one. A quick call to Terry confirmed it was all working again. We took off.

Martin’s main goal was to repair the GPS station on Leppard, and that was our next stop. Here again, the dryness and warmth of the winter and spring amazed us. There were crevasses and even melt ponds all over the glacier. We found the station, and as we had guessed, the solar panels had blown over during the winter. We had expected a major digging effort, but in fact the panels were just below the surface. It required about two hours to excavate them, stand them up again, and re-secure them. On the sat-phone again, the UNAVCO office confirmed we had a working station. Next!

It was getting late, now, the sun definitely lower as we rounded a cape on the ocean and approached the rusty-looking outcrop at Cape Framnes. Here Doug really had a challenge. None of us had seen this site before, and it was steep, icy, and loaded with narrow cracks. The outcrop was perfect for helicopters, deadly for an aircraft. We made three different low approaches, each one ending with some new Scottish swearing (Doug is from Glasgow), and a proper decision not to touch down. We eventually found a site 2.5 miles and 400 meters above our outcrop. Martin, Andy, and I hopped out, grabbed ice axes and the new satellite modem, and started hiking.

It was beautiful now, light winds, cool and refreshing, and we were walking downhill towards a stunning seascape. Walking and walking. The last 400 yards before the rock was a windswept blue ice surface, slick enough so that footing was tricky, but then we made it onto the rock.

The outcrop had a blasted appearance, shattered fragments covering a primeval surface of lakes, sand, gravel, boulders nestled between blue ocean, turquoise sunset sky, and pale blue ice. Truly: an end of the earth, and a spectacular place to be. The fix went quickly, and we paused to take in the surroundings before the hike back to the waiting plane.

***

I want to take this opportunity to thank the people at Rothera and British Antarctic Survey. At every step they have been generous, helpful, responsible, and eager to see us get our work done. I especially want to thank Doug Cochran, who did an outstanding job of piloting, and made the right decision on every single landing and attempt (IMHO). He pushed for our success, but never lost sight of the far more important safety decision. Andy “Boat” was a ready, cheerful helper for whatever we had to do (and he practically dragged my lifeless body up the hill after Cape Framnes, after a very tiring, hugely successful day.) And, when we finally flew into to the Rothera hangar, at 20 minutes to midnight, both Clem Collins (a veritable institution at Rothera) and Andy Barker were there to help get the plane in and unload our gear. Thanks.

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Flask Glacier

November 18, 2010

Terry writes from Boulder, CO:

Ted, Jenn, Martin Truffer, and two BAS Twin Otter pilots traveled to Flask Glacier this morning to service AMIGOS-3. I got a call from Jenn at 9:55 this morning, and AMIGOS-3 took the attached images about 10 minutes later. They had made a pass over AMIGOS-2 at Scar Inlet on the remnant Larsen B ice shelf on the way in, but the pilots decided that the surface was unsafe for landing. The recent warm temperatures have exposed many previously snow-covered crevasses near AMIGOS-2.

I got call from Ted at 10:35. He finished the AMIGOS-3 repair and testing of the downward-looking albedometer sensor. I have also verified in the data we received in the last few minutes that the repair was successful. Next, the team is heading to Leppard Glacier to repair the GPS unit there.

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Flask Glacier and Scar Inlet

February 18, 2010

Ted writes:

The LARISSA Glaciology team continued to get things done in the Larsen B embayment over the past week, but at this time of year the region has a very frustrating weather pattern.  Snow, fog, mist, and even drizzle can shroud the area for a solid week.

The majestic Melville Coast emerges from a thinning haze.

After several days of heavy snow at the Flask AMIGOS site, we awoke to a gradually clearing mist on February 13, and prepared to move fast. Terry Haran and Ronald Ross returned briefly to the previous site at the crest of the ice cap, to re-connect a sensor that failed during our last hour of installation there. Meanwhile I, Martin Truffer, and  Erin Pettit, moved to a second glacier, the wide but relatively smooth Leppard Glacier, to install a continuous-monitoring GPS system.

By flight time the weather was excellent: clear, sunny, and dry with light winds. The flights went perfectly, and within one hour we had the teams at the two sites and making progress. But through it all, to our east, we could see a grey formless shape, a hazy pancake of fog lurking over the shelf. We worked like an assembly line on the Leppard Glacier GPS station, the team barely needed to speak as we worked: this tool here; that method works best for this, here’s this idea to avoid the problem last time, but the fog rose like some inexorable hand, slithering up the glacial valley. How long would it be this time? How long would we be stuck? Worse, we were now a split team again. Terry and Ronald could not rejoin us at the next site, the Scar Inlet Shelf, the lower site, in the center of the fog.

The Scar Inlet is the last vestige of the Larsen B ice shelf—less than 20 percent of a shelf that in the 1980s rivaled the size of Connecticut. Scar Inlet is the southernmost bay of the shelf, and therefore in a slightly cooler climate that the areas that broke up earlier. Its potential for collapse in the next few years, should warming continue even a little, is the driving motivation for our work. Can we get instruments on it ahead of time, and track both the processes of break-up, and the response of the glaciers? In 2002, both of these were stunning: a massive shattering disintegration of a thousand square miles of shelf ice, 700 feet thick, in the space of just a few weeks, followed immediately by a surge of all the glaciers flowing into the affected area, to as much as six times their speed prior to the event. Only the Scar Inlet ice remained; only the Scar Inlet glaciers were un-affected. Scar Inlet stands at the front line of climate change in Antarctica.

As we hunkered down in our tents on Leppard Glacier on the night of February 13, fog and darkness shrank the world to just two dome tents.  Scar Inlet seemed beyond our grasp, a prisoner of a colder, damper summer than most.

February 14 was our lucky day. The fog retreated back down the valley, and the airplane was there within 90 minutes of our weather call. Terry and Ronald were dropped off at the new site first and we joined them by early afternoon. It was by no means a full retreat of the mist, but there were enough ragged holes in the blanket covering Scar Inlet that the pilots managed to get the flights in. The AMIGOS tower was already underway, like a mechanical Frankenstein, slowly coming to life.  As they left, the lead pilot shook his head: “I’m worried about this fog. You guys are going to be here for weeks.”

As I said, Scar Inlet is on the verge of collapse, rent with shallowly buried crevasses, because melt in summer removes nearly all the winter snowfall. But we had no idea just how precarious the situation was. As part of building camp, Terry dug a pit, to “accumulate food wastes,” shall we say, and nearly lost the shovel down a narrow crack about 50 feet from the tents. We took it seriously. Erin put on skis and her harness, and with Martin watching, she probed the area around camp. We found one part of the crevasse that might be wide enough to pose a hazard, and marked it. Overall, the camp seemed safe. Traversing with the radar that evening, we probed on skis for 6 kilometers (4 miles) to the north, and found no more weak areas. Needless to say, we dug a different pit.

Erin probes the ice fracture outside of camp.

February 15 was cool, dismal, even dank, as the fog and clouds closed in again. At this low altitude, just barely above sea level, the air felt heavy and wet. We had seen nothing beyond the runway flags, except occasionally the lowest parts of hazy rocks in the distance. For the most part, we were once again floating in an infinite grey ball, with no horizon. But we worked continuously to get the AMIGOS station in, and by 9 p.m., we had raised the tower and secured it, digging three deep pits and a central large pit for the anchors and the tower base.

The next day, we sensed a change. The mist was thinning. The sun was still obscured, but too bright to look at. We saw shadows for the first time in days. Not quite flying conditions, but close. We radioed a report on the trend to the pilots at Rothera Station, and then took off quickly for a second radar survey.

About a mile out of camp, it happened. Behind us as we skied, the fog began to thin to nothingness, and a stupendous landscape emerged. Martin was the first to notice it, as he knelt to adjust the radar system. It was as if we had been standing in a national park, a world heritage site, that had been hidden behind curtains. The satellite images could never do this justice: Leppard and Flask glaciers flowed down toward us, past a giant rampart of rocky peaks to merge at our feet into a vast plate of ice. In the harnesses, we were giddy: we stopped, snapping pictures, laughing and joking. Our camp seemed like a few fallen toys on the snow at the foot of the range and glaciers. I’m sorry: I just could not get it all to fit into the camera. The majesty of the place was beyond recording.

Ted and Martin Truffer ski across Scar Inlet.

But February 16 was to be a roller-coaster day. As we skied back to camp, looking forward to a return to Rothera, we noticed something odd about the AMIGOS tower in the distance. There was a large black lump clinging to the side of it. Skiing closer, we could see that Terry was near the top of the tower. Something was wrong.

As we got to camp, we learned that the camera on the AMIGOS had failed sometime after we hauled the tower upright. Fixing it would require hours, and even that was not certain; and the planes would arrive within 45 minutes, and they could not wait.

Wow. To have all this to look at, and all the events that might indicate an impending breakup, and no eyes on the AMIGOS. Ronald informed us that there was no way he could fix it out here, and so dejectedly, we removed the camera from the system.

The planes arrived. The distraction of the broken camera, and our long ski back from the radar traverse meant that we were completely unprepared for them. Camp was still scattered and unpacked. But the pilots pitched in, (I want to say: outstanding pilots, Richie Cameron and Dave Edenborough, both in flying and in supporting the science work), and began to help us pack the two aircraft.

That is when the second stunning event happened. We had been at the camp for three days, stomping around everywhere, and had skied for kilometers, finding just one narrow crack. But as one of the pilots dragged some heavy cases across the snow, we heard a shout – and turned to see him waist deep in a 2-foot-wide crevasse. The chasm was nearly black at the bottom, at least 20 feet; it was a “dead” crevasse, formed upstream, and the sides were coated with icicles and frozen rivulets of water from previous summers. The pilot was shaken, unhurt, but the shock of it drew us down even further. Martin probed a safer route, and the mountaineers and I did the rest of the packing, on skis for safety.

The song that came to mind on takeoff: “Whipping Post” by Eric Clapton. But as we flew, and talked things over, a new resolve came to us. We could fix the camera with a quick helo flight and appropriate precautions. And crevasses comes with the territory of exploring active places on ice, places that are changing as climate changes.  With one more week on the ship, we might, just might, be able to put in another station or two, on some of the most interesting ice terrain on Earth

Erin found some food in her pack, crackers ground nearly into gravel, chocolate, and some cheese. It would have been trash by any ordinary standard, but by this point Terry and I were in full ‘field mode’: this was food, and we were hungry.

Terry and Ted enjoy a much-needed snack.

By the time we landed, the song had switched to “Fanfare for the Common Man.” That is how to fly over the Peninsula landscape.  We are now waiting for a flight from the British base to rejoin our colleagues aboard the Palmer.

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A taste of success

February 11, 2010

Ted writes (via Iridium modem):

On Saturday, a long-awaited spell of clear weather threw the LARISSA Glaciology Team into fast action. Three of the five stations we hope to put in this are now up and running. Our highest-priority site, Flask Glacier, which flows into the last remaining part of the Larsen B Ice Shelf, is now fully instrumented.

Clear weather over Flask Glacier allowed the team to fly to several sites to set up AMIGOS stations.

The weather was spectacular for nearly three days, beginning on Saturday. With our first flight, our pilots, Richie Cameron and Dave, brought out the GPS system, a continuously operating precision GPS designed to record any subtle changes in the ice flow, even ones at a tiny scale, occurring on a daily or monthly basis. The GPS will also provide a detailed record of any general acceleration if the ice shelf thins and breaks apart.

Every time the plane engines rev, and the plane starts to move, a song just jumps out of my head, like a second heartbeat; Satisfaction by the Rolling Stones for the first flight; Ode to Joy later that day; Ring of Fire by Mr. Johnny Cash on the way back from the ice core camp.

Setting up the Flask GPS took us about 4 hours, and in a second flight, we moved down-glacier to the Flask AMIGOS site. AMIGOS is a heavily instrumented science station, sort of a super weather station with measurements of the ice added in. Terry and Ronald began to assemble the station even before the tents were set up, and had the basic framework laid out by evening. All five of us then set the lower Flask camp, still basically a mountaineering setup with backpack tents and few luxuries. But with five of us now in the cook tent, there was a camaraderie that made up for some of the tough conditions. For dinners lately, we’ve had chili, pan-grilled steak, tofu thai curry, and tonight, with luck and a bit of imagination, jambalaya.

A day trip on Sunday back to the Ice Core Camp got the AMIGOS station there stood up and operational (we had it running, but not erected, for about a week), and on Monday we finished the Lower Flask AMIGOS, the most sophisticated yet. It contains a full-precision GPS (from the GRS-1 board built by TopCon Inc.), a steerable camera system, a full weather station, a sun and reflectivity sensor, and a thermistor string extending 12 meters into the snow. We worked 13 hours that day, until darkness came.. Darkness and night have begun to return here.

As we worked on Monday evening, the fog and snow returned. Tuesday we managed to survey several short radar lines, but fog and poor lighting conditions made it risky to explore too far; the camp is surrounded by huge crevasses. Wednesday we returned to our waiting-for-sunshine mode, that is, looking over the data, sorting the food, reading books, walking short distances for exercise, quoting old movie lines and other trivia games, and just generally hanging around, until the next break.

And with the end of southern summer coming on, we need that break soon. One last push to go.

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