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Thursday, 19 June 2008 04:05
Day 58: More wet field work
We knew that studying the stream would likely get us wet, but it wasn’t river water that soaked us today. Over night the weather detiorated further and we got rain and snow most of the night. This continued throughout the day without much of a break, though we did get a variety – snow, rain, sleet, freezing rain, slushy snow – pretty much anything that could fall around freezing. Nevertheless, it was still a productive day.
One of our goals is to get a sense of how much water leaves the glaciers and flows towards the ocean, and then use this information to better understand how much water glaciers in this region contribute to the major rivers of this region. But this is tricky business. ‘Normally’ stream discharge is measured by attaching instruments to the pier o...
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Wednesday, 18 June 2008 03:49
Day 56-57: Typical weather for the terminus
The glacier is just a visitor to this valley, and nowhere is this more obvious than at the terminus. Where the glacier has recently been is a jumble of debris where once was order, like the aftermath of Turner visiting his toy box. Hunks of rocks are strewn all over the place, some stranded in high places, some washed continuously in the river, and everywhere in between. Apparently the party is not completely over, as we witnessed a boulder the size of a school bus tumble down the mountain, catching air and doing flips before crashing into the valley floor not far from us. This is where geomorphology comes alive and works on time-scale faster than glacier motion.
Jason and I were up at 6AM yesterday to begin staging equipment for our trip to the terminus, by shuttling a load...
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Monday, 16 June 2008 03:37
Day 55: Slush flow announces the true start of summer!
Summer truly arrived today with an enormous slush flow which opened the main stream on the glacier. Slush flows are like low angle avalanches. Water slowly saturates the snow and makes it heavier and more fluid. At a certain point, the weight of the water can no longer be held back by the snow matrix and gravity takes over. Over the past few days we had been watching meltwater pool up within the stream channel from last year. This morning there was standing water visible within a large section of it. I set up a time-lapse camera hoping to capture it, and about 10PM it happened. I was in my work tent preparing for a few days of work at the terminus when I heard a loud roar. I ran out and saw a wall of slush and water working its way downglacier. We all stood and watched as the peak rushed p...
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Sunday, 15 June 2008 03:31
Day 52-54: Studying lenses of ice and glass
Our primary occupation the past few days has been studying lenses. Jason is studying ice lenses within the firn, and I’m studying glass lenses on my camera. It’s difficult to say who’s job is harder, but I suspect it’s Jason’s.
Ice lenses are layers of ice that form within the snow. The surface of the snow warms up from the sun, melts, then drips into snow beneath it. When this water hits colder snow, it tends to freeze. When it does, it prevents more meltwater from dripping down further, since the ice is too dense for water to flow through. So the additional water has to spread out to the sides, where it too will find colder snow and freeze. This goes on throughout the day (or spring), such that wide layers of ice form within the snow. We call these ice lenses. As...
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Thursday, 12 June 2008 02:34
Day 51: Sun + Snow = Clouds, at least in summer
Sunshine melts snow, but it also turns it into vapor which tends to rise and later condense into clouds. At McCall Glacier, we have the neat opportunity of watching this happen before our eyes. Today was a sunny, clear day, at least on the synoptic scale of regional weather. But once the sun rose high enough to increase its energy flux to the surface, it began creating clouds locally. Because our camp sits within a bowl shaped valley, we can watch the sun as it swings from the east to the west in a big circle and heats up the backside of our valley walls. So when the sun is in the east, we see clouds forming directly behind our eastern valley wall, and as it swings to the south we see clouds there but not in the east, and so on. To better visualize this, I took a sequence of panoramas thro...
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Wednesday, 11 June 2008 02:30
Day 49-50: Jason sinks his teeth into the firn
One of the questions Jason is trying to answer as part of his PhD is ‘How much of the snow that falls here gets refrozen within the glacier and how we can apply this knowledge to improve our ability to model this process on other glaciers?’ So the past two days Jason and Joey have been busy getting more experienced with the shallow coring drill and developing a plan for measurements for the next few years. It’s a tricky question and one that has not been answered well as yet, largely because it is so tricky to make direct measurements of this internal accumulation of ice. The state of the art paper was written 30 years ago, based in part on research done on McCall Glacier. So it seems like there is still a lot of progress that can be made if the right work plan could be developed. Ou...
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Monday, 09 June 2008 02:23
Day 48: Installing survey stakes to measure index velocities
We left early again today to install two more stakes, this time in locations we have previously installed stakes. The glacier is always in motion, and in these locations it moves about 15 meters per year. This means the stake we installed last year is now 15 meters down-glacier. We keep installing poles at the same initial location so that we can track how the glacier’s speed is changing with time. We cant just keep measuring the same pole because the glacier’s speed varies with location, and as the pole moves into a new location its speed will change. In this case the fastest moving part of the glacier is about 2/3s of the way towards the terminus, above and below this it moves slower. By installing poles each year in the same initial location, we can then tell whether that part of th...
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Sunday, 08 June 2008 02:14
Day 45-47: Spring arrives on the glacier
Like a switch was flipped, we changed from winter to spring, in several ways. A few feet of fresh snow had fallen during the last week of May and early June. Then we had 3 days of warm, mostly sunny weather, just long enough to get the drill gear and team out and the newest member of team in. By the time Dirk took off with our final load of gear, a serious rain had begun and spring was here – the snow was melting, the streams were running, and we began scrambling to catch up on all of the winter work we had wanted to get done in the past month but just didn’t have the time or weather. With this new weather also came a change in work dynamics, with just five us now and all focused on our process studies, we are a much leaner and more focused team, concentrated on supporting Jason’s pr...
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Tuesday, 15 July 2008 16:31
Research team draws 150-meter ice core from McCall Glacier
A 150-meter ice core pulled from the McCall Glacier in the Arctic National Wildlife Refuge this summer may offer researchers their first quantitative look at up to two centuries of climate change in the region. The core, which is longer than 1 1/2 football fields, is the longest extracted from an arctic glacier in the United States, according to Matt Nolan, an associate professor at the University of Alaska Fairbanks Institute of Northern Engineering who has led research at McCall Glacier for the past six years. The sample spans the entire depth of the glacier and may cover 200 years of history, he said. What we hope is that the climate record will extend back into the Little Ice Age,said Nolan. Up until the late 1800s these glaciers were actually gr...
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News And Announcements
Tuesday, 15 July 2008 15:52
Iceberg Voyage Is Over, but the Blogs Live On
Nancy Etchemendy writes:
Hi, everyone --
Our fascinating Antarctic iceberg research voyage aboard the NSF icebreaker Nathaniel B. Palmer is over now and we are safely home again enjoying the warmth and light of summer. But my two blogs about the trip will remain online as a polar teaching resource for kids of all ages. Over the next few months, I will continue to enrich both blogs with high-quality links to sites of related interest and with additional facts about the subject material -- icebergs, the Antarctic oceans, global warming, Antarctic sea life, scientific method, and much more. Both blogs can be accessed via icebreakerblog.org
...
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