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The Polar Museum: news blog

We’re All Going on A Summer Not-Holiday: Part 2

I promised a follow-up post on what we actually did on fieldwork upon our return, so, here goes. In this post I’ll focus on the science; in a subsequent one, I’ll talk a bit more generally about the wider fieldwork experience.

First thing I will say is that from a scientific point of view, the fieldwork was a roaring success. We achieved all our objectives, despite arriving four days late (more on that in the next post). We set up and used several different instruments, which I’ll explain a bit more about below.

The first instrument, and the one I ended up being responsible for was the radar interferometer, which we set up to observe the calving front. To explain what a radar interferometer is: the first part, radar, is fairly straightforward. We all know what a radar is. It’s that thing with the glowing green screen that goes ‘beep’ and shows a dot as the enemy aircraft/tank/monster/etc. is detected by it in every action movie ever. Obviously, however, a dot showing there’s a calving front there isn’t terribly useful for us. This is where the second part comes in, the interferometer. Interferometry is the use of multiple discontinuous small receivers to crate a virtual massive receiver, which gives you much better resolution, and, critically, the ability to get a 2D picture of the target. It’s used a lot in astronomy – rather than building one very large telescope, you build several smaller telescopes and space them out a bit, giving you the same result (with the application of a bit of maths and computing power) for much less effort. Our interferometer had a baseline (the distance between the receiving antennae) of only about 15 cm, but it was enough for it to produce very detailed 2D scans of the entire calving front every three minutes, for three weeks. Continuously. That’s a lot of data, which we can use to study the processes behind calving, as well as the behaviour of the ice mélange immediately in front of the glacier, once it’s all been processed.

The radar interferometer, overlooking Store Glacier. The top antenna (the horizontal bars) transmitted; the two lower ones received.

Our second big instrument, as such, was the drones. Six of these were brought along, and, after a few initial technical issues, they worked almost flawlessly, making several successful flights at the calving front and at the site on the ice, 30 km inland. Despite every landing being essentially a tenuously-controlled crash. The drones were fitted with a digital camera, and took hundreds of overlapping photos of their target areas. We hope this will allow us to track very small changes in the ice surface between flights, but we’ll need to process more of the data to see how successful that is.

Tinkering with a drone at the calving front.

The third major group of instruments we set up was the time-lapse cameras. These are, again, fairly standard digital cameras, this time set up on tripods overlooking the calving front. We set up ten of these; four on the south side of the glacier terminus; six on the north side. These, ideally, will each take a photo of the calving front every five minutes for the next five years. Hopefully, they won’t break too badly in the meantime. Again, the array of overlapping photos should allow us to track terminus changes and calving processes over the longer term, which will prove useful in detecting trends and seeing how representative the data gathered this summer are.

And tinkering with a time-lapse camera….

The final set of instruments we used were the GPS stations. Four of these were set up at the inland site to allow us to track ice velocity (speed and direction) for the next few years (until they eventually break!), which will be useful in complementing the other datasets, as well as providing long-term information on the health of the glacier.

A very low-tech GPS station at the calving front. The inland ones were a bit more sophisticated.

We now have several terabytes of data (1 TB = 1000 GB = 1,000,000 MB) to process. That’s our work all sorted for the next few months….

And, to finish with, here’s a couple of videos of science in action: launching and landing a drone. Ignore what appears to be the giant space laser in the launching video – it’s just the Sun.

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