Thought I'd share some pictures from our fieldwork season so far.
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The mass balance describes how much mass a glacier gains or loses per year. If the lower parts of the glacier lose more mass in summer than the upper parts gain through snow accumulation, the glacier will shrink; if it is the other way round it will grow, and if the gains and losses balance out the glacier is in equilibrium state and remains the same size. There are different ways to measure the mass balance. You can do it with remote sensing data, or you can use geodetic, hydrology, or modeling based approaches. Or you can use the "direct glaciological method", which means actually going out and measuring things on the glaciers. Each method has its pros and cons. There are other, more complex processes going on at various types of glacier, but if you want one number to describe the state of things, the mass balance is a pretty good start. Mass balance data from all over the world are collected by the WGMS.
At our office we do a bit of everything but a large part of summer is taken up by running around on glaciers we monitor via the direct method. When snow depth is greatest (late spring), we go and dig deep holes down to the ice or last year's snow, provided last year's snow survived the summer. We measure the density of the snow and calculate the amount of water we would have if we melted it all. This is the winter balance, or the amount of mass gained during the accumulation season. Mostly we deal with something between 3 and 6 meters, but we've topped that. Beyond about four meters you need to start making terraces, or have really long arms. There is a certain sick satisfaction to be gained from digging a nice big hole and some people make an art form out of it, but mainly it makes your back ache. In places where it snows more than in the Alps, people use snow corers to avoid digging 10 meter deep holes.
Spring pit Mullwitzkees:
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Hallstätter Gletscher:
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June is for Heliskiing
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Not really.
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No heli to go back down :(
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In July we walk.
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Mostly.
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Two colours!
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More walking.
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Here we can take a lift up and ski a bit.
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Until the snow runs out.
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Wonder who lost that 30 years ago.
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More walking.
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Once the snow has melted in summer, ice ablation (fancy word for melting) starts. To measure this, we drill long (usually around 8-12 m) stakes into the ice with a steam drill and periodically check how much of the stake is sticking out of the ice. The end of the hydrological year (Sept 30) marks the theoretical end of summer ablation and we do a final reckoning of how much ice has melted on the tongues and how much snow remains in the higher regions of the glacier (if any). We then figure out how much net loss (or gain) occurred that year, averaged over the entire area of the glacier.
The steamdrill is a big pot where you heat water, which then comes out of a hose as hot steam.
#babeswithsteamdrills
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Know how I know it moves?
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Cookie monster sees you.
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Who wants to shred the park?
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Or maybe the XC track?
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Glad you can't see these in winter.
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Walkwalkwalk (note steamdrill)
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Three summers worth of snow retreating up the hill.
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The summit of Dachstein is an excellent place to experience the inspiring loneliness of the wild mountains.
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More holes
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Are we there yet?
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Lonely glaciology slave.
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Lovely and pristine.
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In general, summer is more important for the mass balance than winter. Even small summer snowfalls slow down the melting process considerably because the new snow reflects most of the incoming radiation, which would otherwise melt the ice. The past two summers were rather wet and cool in the Alps and the mass balance was less negative than in previous years at most of our glaciers and even a tiny bit positive on some. This year the summer has started off hot and almost all of the winter snow that accumulated over the past seasons has melted. We've already seen between 1 and 4 meters of ice melt in the lower parts of our glaciers due to the warm weather and a relatively low winter snow pack.
Mid July 2013 vs beginning of August 2015:
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Ten days:
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Three weeks:
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High time to get out of here and down to snowy south america!
