GeoLog

Imaggeo on Mondays: Trapped air

Can you imagine walking into the depths of an icy, white, long and cavernous channel within a thick glacier? That is exactly what Kay Helfricht did in 2012 to obtain this week’s Imaggeo on Mondays photograph.

Tellbreen Glacier is a small glacier (3.5Km long) in the vicinity of the Longyearbyen valley in the Svalbard region of Norway. Despite its limited size, it is an important glacier. One of the key parameters scientist use to understand how glaciers are affect by a warming climate is how the melt water is transported through to the front of the glacier. The majority of models utilise data from temperate or polythermal glaciers, i.e., glaciers which have free water within the icy matrix. Tellbreen is a cold glacier, meaning the basal layers of ice are frozen to the glacier bed; despite the traditional view that cold glaciers are not able to store, transport and release water, Baelun and Benn, 2011 found Tellbreen does this year round.

Trapped air. (Credit: Kay Helfricht via imaggeo.egu.eu)

Trapped air. (Credit: Kay Helfricht via imaggeo.egu.eu)

Kay visited Tellbreen whilst at the Artic Glaciology course at the University Centre in Svalbard. ‘Each weak one excursion led us to glaciers in the vicinity of Longyearbyen’ says Kay, ‘this day we visited the glacier Tellbreen. Near the tongue of the glacier the outlet of an englacial channel enabled us to explore the inside of the glacier. We went for some tens of meters into the channel.’

What the group found were that the walls of ice either side of the channel contained impurities, from stones to gravel, as well as mud and also water. The image above shows ‘air trapped in the ice-walls of the conduit at a time when the conduit would have been filled with meltwater of the glacier’ explains Kay. Air accumulated in bubbles at the roof of the conduit. When the water in the conduit started to refreeze along the side-walls, these smooth lenticular bubbles were trapped and stored in the ice. Studying the bubbles and other impurities in the ice can give hints on the history of the glaciers ice flow and its thermal regime over several decades.

References

Baelum. K., Benn. D.I.: Thermal structure and drainage system of a small valley glacier (Tellbreen, Svalbard), investigated by ground penetrating radar, The Cyosphere, 5, 139-149, 2011

Naegeli. K., Lovell. H., Zemp. M., Benn, I. The hydrological system of Tellbreen, a cold-based valley glacier on Svalbard, investigated by using a systematic glacio-speleologicalapproach, Geophysical Research Abstracts, 16, EGU2014-6149, 2014 (conference abstract)

 

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

Laura Roberts Artal is the Communications Officer at the European Geosciences Union. She is responsible for the management of the Union's social media presence and the EGU blogs, where she writes regularly for the EGU's official blog, GeoLog. She is also the point of contact for early career scientists (ECS) at the EGU Office. Laura has a PhD in palaeomagnetism from the University of Liverpool. Laura tweets at @LauRob85.

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