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Volume 10, issue 3
The Cryosphere, 10, 1125-1145, 2016
https://doi.org/10.5194/tc-10-1125-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
The Cryosphere, 10, 1125-1145, 2016
https://doi.org/10.5194/tc-10-1125-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 27 May 2016

Research article | 27 May 2016

Imaging air volume fraction in sea ice using non-destructive X-ray tomography

Odile Crabeck1, Ryan Galley1, Bruno Delille2, Brent Else3, Nicolas-Xavier Geilfus1, Marcos Lemes1, Mathieu Des Roches5, Pierre Francus5, Jean-Louis Tison6, and Søren Rysgaard1,4,7 Odile Crabeck et al.
  • 1Department of Geological Sciences, Centre for Earth Observation, University of Manitoba, Winnipeg, Manitoba, Canada
  • 2Unité d'Océanographie Chimique, MARE, Université de Liège, Liège, Belgium
  • 3Department of Geography, University of Calgary, Calgary, Alberta, Canada
  • 4Arctic Research Centre, Aarhus University, Aarhus, Denmark
  • 5Centre Eau terre et Environement, INRS-Été-Quebec, Quebec, Canada
  • 6Laboratoire de Glaciologie, DSTE, Université Libre de Bruxelles, Bruxelles, Belgium
  • 7Greenland Climate Research Centre, Greenland Institute of Natural Resources, Nuuk, Greenland

Abstract. Although the presence of a gas phase in sea ice creates the potential for gas exchange with the atmosphere, the distribution of gas bubbles and transport of gases within the sea ice are still poorly understood. Currently no straightforward technique exists to measure the vertical distribution of air volume fraction in sea ice. Here, we present a new fast and non-destructive X-ray computed tomography technique to quantify the air volume fraction and produce separate images of air volume inclusions in sea ice. The technique was performed on relatively thin (4–22cm) sea ice collected from an experimental ice tank. While most of the internal layers showed air volume fractions < 2 %, the ice–air interface (top 2 cm) systematically showed values up to 5 %. We suggest that the air volume fraction is a function of both the bulk ice gas saturation factor and the brine volume fraction. We differentiate micro bubbles (Ø < 1 mm), large bubbles (1 mm < Ø < 5 mm) and macro bubbles (Ø > 5 mm). While micro bubbles were the most abundant type of gas bubbles, most of the air porosity observed resulted from the presence of large and macro bubbles. The ice texture (granular and columnar) as well as the permeability state of ice are important factors controlling the air volume fraction. The technique developed is suited for studies related to gas transport and bubble migration.

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We present a new non-destructive X-ray-computed tomography technique to quantify the air volume fraction and produce separate 3-D images of air-volume inclusions in sea ice. While the internal layers showed air-volume fractions < 2 %, the ice–air interface (top 2 cm) showed values up to 5 %. As a result of the presence of large bubbles and higher air volume fraction measurements in sea ice, we introduce new perspectives on processes regulating gas exchange at the ice–atmosphere interface.
We present a new non-destructive X-ray-computed tomography technique to quantify the air volume...
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