Imaging the Ice…

Hi again from Adam in Norway’s Finse station. Today we had a “bad” weather day – some clouds rolled in, obscuring the view of the Hardangerjokull ice cap and it’s been generally chillier. However, considering that I’ve previously conducted Arctic fieldwork in blizzards and whiteouts, we can hardly consider a bit of cloud as “bad” (hence the inverted commas!) and we’re still really lucky with the weather. And to be honest, a low-hanging cloud looming above you does give the fieldwork a bit of Middle-Earth dramatics…!

Benny and the radar 'snake' head north, under a cloudy Midtdalsbreen glacier.
Benny and the radar ‘snake’ head north, under a cloudy Midtdalsbreen glacier.

Thanks to the great weather, data have been rolling in and I thought I’d share an initial image. The data you can see here can be considered as a cross-section through the glacier.  Obviously, the section I’m showing here is hot-off-the-press and requires much more processing, but we can already spot the change in the ice conditions!  You’ll remember that we’re looking for the tell-tale signs of ice frozen to its bed and, in my first blog, I gave an impression of the sort of things we’re looking for in our radar data; ‘fuzzy’ patches of the glacier are a strong indicator of unfrozen water within the ice, whereas the ‘transparent’ sections suggest that the glacier is completely frozen.  This particular section is a GPR profile from the upper reaches of Midtdalsbreen, down to its margin and onto its foreland.

An example GPR profile from Midtdalsbreen.  Even at this early stage of the work, we see clear responses from the glacier bed, the englacial water, and the entirely-frozen zone at the margin.
An example GPR profile from Midtdalsbreen. Even at this early stage of the work, we see clear responses from the glacier bed, the englacial water, and the entirely-frozen zone at the margin.

We see the glacier bed very strongly in this image; whilst it appears to slope upwards, we must remember that surface topography slopes downwards, so the glacier bed is probably not as steep as it appears here. However, the ice thickness will still be pretty accurate, and you can see that Midtdlasbreen has a maximum thickness exceeding 65 m thick along this particular line. There are plenty of sections of this dataset which show the ‘fuzzy’ responses of liquid water; however, you’ll notice that there is a transparent layer which undulates across the length of the profile and – critically for Benny’s hypotheses – is also present at the very edge of the glacier, right down to its bed. These images are very promising indeed, and we’ll be adding detail to them during further acquisitions and in later data processing.  This particular dataset took about 15 minutes to acquire, and is around 1 km long.  Efficient acquisition!

Sadly, Benny leaves tonight as he is off to the EGU conference in Vienna. He’s presenting a poster on his day-job research, in which he interprets signatures of ancient ice-sheets in seismic datasets from the North Sea. I’m sad to see him go, but he’s left me with a good few areas of the glacier to survey and I look forward to welcoming Dr Anna Hughes to Finse to replace him! Benny’s final duties were somewhat ‘janitorial’, dusting down the equipment boxes of the snow they’d accumulated during the journey from Midtdalsbreen back to Finse Station.

Benny's last night... Brushing off icy boxes before bringing them indoors.  See you soon!
Benny’s last night… Brushing off icy boxes before bringing them indoors. See you soon!

Anyway, I’ll get Anna to post a couple of words about her own research one evening. Until then, it’s bye from Finse!

Advertisements

One Reply to “Imaging the Ice…”

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s