Tuesday, 8 April 2014

Off to camp!

March 28th - The weather cleared up in the evening, so Christian, Bruce, Marc and Petter flew out to locate a site and set up the ice camp. It was windy where they landed and apparently it was quite a lot of work to get some tents up. The following morning Rachel, Chris, Justin and myself joined them on the ice. Here's a picture of the sea ice off the north coast of Greenland, and then a picture of the camp as we approached:

They had picked a big multi-year floe – thick ice (3-5m) that had survived last summer’s melt season. Multi-year ice tends to have much more topography than first-year ice and this floe had a very varied surface. There were fairly large pressure ridges surrounding us where the floe had be crushed up against neighbouring floes, large flatter areas where last summer’s melt ponds had been, hummocks where last summer’s ridges had been, and everywhere there were wind blown ice drifts and sastrugi. Sastrugi are wind blown erosional/depositional features of the surface, and appear quite similar to ocean waves - 10s of centimetres high and a few meters long - but frozen in time. This pic that Rach took gives an idea of the topography of the ice floe:

Most places there was a fairly thick snow layer – the deepest we measured was around 90cm but on average it was maybe 30 or 40cm. The top layer tended to be a firm crust called a wind slab that was maybe 10cm thick and made walking around much easier. About the bottom 10cm of the snow pack tended to be depth hoar – larger crystals formed by sublimation of water vapour due to the temperature gradient between the top and bottom of the snow pack. The depth hoar is much more loosely packed than the top layers (often the crystals aren’t bound at all) and the effect of the hard crust and the greater amount of air left between the spaces of the depth hoar crystals meant that your footsteps echoed in the snowpack as you walked around. Here's a close up of the depth hoar crystals, thumb for scale!

The flight out to the sea ice was very exciting: the four of us, plus a load of the scientific equipment all packed into the back of the Kenn Borek Twin Otter. We had excellent views of the north Greenland fjords and the sea ice all of the way. When we arrived at the camp the pilot descended to around maybe 100m and made multiple passes over the floe to get a better assessment of the landing conditions. The landing itself was great fun, a bit bouncy but if you put out of your mind the possibility of the plane falling through the ice then it was calm enough!

When we arrived there was a little bit of wind, but it quickly died down. By the late afternoon/evening of the 29th it was very still and sunny. To the south we could see the mountains of northern Greenland and Cape Morris Jesup, the most northerly land on the Earth. Here you can see the mountains:

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