Hinterim updates

Team GLARE is now back, safe and sound in Leeds, sans dodgy field facial hair. From the comfort of an office where crampons are not required, the terrain is less hard on the knees and afternoon convective thunderstorms are less frequent, we can reflect on some hard – but successful – work.IMG_20180815_161433.jpg

After their brief Hintermission at the Hochjoch Hospice, Josh and Tom returned to the ice for another 11 days in the field. In a Herculean effort, hiking a 35 km round-trip, our colleagues from Innsbruck (and morale officer, Mika the dog) resupplied us with some much-needed potatoes and pumpernickel, and petrol for the generator they had also carried up. The generator was used to recharge the batteries for a dGPS base station, essential for precisely georeferencing our surveys, so the care-package was most welcome!

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In their remaining time, Josh and Tom surveyed and re-surveyed, then surveyed some more, reaching a grand total of 69 surveys of 16 plots on different surfaces, with most plots surveyed four or five times each. In addition, four surveys were completed of the area around the stationary mast, which logged (nearly) continuously for the duration of the campaign, while the mobile mast was moved from its starting point to three subsequent sites for three or four days at a time, with a survey undertaken at each site. We managed to squeeze in a brief Hinterlude, taking a day off to ignore all of the sites and put our feet up. We even scraped together a cheese-board, bringing a Hinter-sophistication to the hut.IMG_20180809_113019.jpg

Importantly, the wind towers remained vertical and were able to provide a near-continuous set of observations of wind speed, direction, air temperature and relative humidity for the whole 15 days. Upon leaving, the reigns were handed over to the Innsbruck team who will tend their instruments and ours for another week or so, extending the dataset even further. Not only will the towers eventually provide us with some distributed z0 values for Hintereisferner, but they will also be used in studies of katabatic (glacier) winds by the Innsbruck team. These localised, density driven winds reach a maximum speed relatively near to the surface, exhibiting a logarithmic velocity profile from this maximum height to z0, where the speed is zero. As you can see in the clip below, the cup anemometer on the top of the mast is spinning a lot faster than the lowermost – an encouraging sign for our data!

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While it will take a little time to process the microtopographic surveys and find out exactly how quickly the ice surface is changing, the glacier was definitely not afraid of showing a little dynamism while we were there, and the surface evolution was pronounced. This before and after shot shows a rock pedestal (the boulder is ~2 m along its longest axis) on the day the plot was first surveyed, and then again just three days later.

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This made for some interesting terrain to survey and traverse, as rills and channels become more exaggerated, crevasses widened and snow plugs disappeared. By the time we left, we noticed huge differences in the nature of the surface compared to when we arrived. We’re looking forward to processing some of the data to try and quantify the changes we observed, and finding out what this means for the evolution of z0 across the glacier and through the melt season – we will provide updates with some initial, hopefully hinteresting, results in the coming weeks.

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Hintermission

All things come to an end – today two things did. First, it was time for Mark to leave Station Hintereis and return to the UK. Second, all the batteries came to the end of their charge. The latter was a real shame!!!

So, Team GLARE left Hintereis together, armed with a bag full of batteries (light as a feather, ahem) and headed for the Hochjoch Hospitz, a hut just two hours walk/haul downvalley.

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Can you guess which room Team GLARE stayed in?

P1100963.JPG   Plans are now afoot for our great hosts to walk a generator up to the Station (!!) and the remaining members of Team GLARE are powered up and ready to continue the surveys!

In our next post to ‘Rough Ice’ we’ll try to demonstrate some of the evolution we’ve observed, and report on the verticality of the towers!

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Hinternational Hiking

Today the team split up as Mark and Lindsey went on a looong hike to check on the status on the long range in-situ Terrestrial Laser Scanner that overlooks the entire Hintereis glacier. Meanwhile, Josh and Tom faced further photogrammetric surveys and a check on the wind towers to see if they were still vertical (spoiler: they were, hurrah!) and connected to the batteries (spoiler: one was not, booo).

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The hike to the TLS involved a brief crossing over the border to Italy after climbing a relatively steep section of ice. P1100926

What a location for a TLS! It has a viewpoint over almost the entire glacier and will be deployed at ~3 day intervals to help us scale up our findings to the entire glacier. There Rudi was on hand to delineate our area of interest and get the scans started. This will be a fantastic resource for the GLARE project!

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Hinter-Act Two

On day 2, a soggy team went back down onto the ice to survey some smaller plots. These surveys will be used to observe the changes in different ice surfaces over the duration of the field campaign, potentially the longest study of its kind to date. The microtopographic survey techniques used here take advantage of the relatively fast, fine resolution capabilities of SfM, and the results will be used to investigate the evolution of z0 during the peak of the ablation season.

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Initial tests suggest we are achieving the high resolution data we require for subsequent analyses – thanks also to the dGPS located right outside our doorstep!

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Several days of measurement have already revealed that the Hintereis glacier is already showing signs of dramatic surface changes!

Hinter-Act One

After months of planning, Team GLARE arrived in Innsbruck, Austria, from Leeds late on the 30th June, after successfully guiding two flat-packed wind towers and a bag-load of batteries through airport security in Manchester and Munich. We travelled by bus between Munich and Innsbruck, minimising costs and carbon footprints.

The next morning we assembled at Rofen with a team of scientists all interested in studying the Hintereis glacier, and all taking complementary measurements that will yield an impressive amount of data (a scheme masterminded by Lindsey Nicholson).

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Tom and Josh were helicoptered up to Station Hintereis (3026 m) along with essential field supplies, including dGPS, wind towers, gas bottles, solar panels and of course, plenty of pumpernickel. The other teams, including Mark, were dropped at different locations on the ice to deploy sonic anemometer masts and meteorological stations, while the wind towers were assembled at the hut. These two instrumental set ups provide two ways of measuring the turbulent fluxes of sensible and latent heat in the atmosphere near the glacier surface, and can be used to measure aerodynamic roughness length (zo), which is the height above the glacier surface at which wind speed drops to zero. Installing both will allow results to be compared and then used to validate z0 values obtained using microtopographic surveys (a third method).

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Station Hintereis is commonly used for short one or two night excursions from Innsbruck. As Josh and Tom have made the journey from Leeds and will be staying at the station for around two weeks, they will be its longest-term residents – to the knowledge of any of the crew. Perched high above the Hintereisferner, it’s not a bad place to spend a couple of weeks!

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On the first day we installed the two wind towers; one will maintain position next to a sonic anemometer mast for the duration of the field campaign to ensure comparability (mast 1), and one will be left in place for three/four days at a time then moved around the glacier to collect data from different locations (mast 2). A survey of the immediate area around mast 2 was carried out using a digital camera mounted on a 6 m pole, the photos from which will be used to construct 3D digital elevation models using structure from motion photogrammetry. We carried out similar surveys of smaller plots on varied surfaces, in order to try to characterise the range of roughness characteristics present on the glacier.

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With a hard and long day’s work behind us, Team GLARE made the long commute back up to the hut. Unfortunately, a convective thunderstorm made the steep climb back to the hut very interesting with rock faces turning into waterfalls!

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