Odile Crabeck, PhD student from University of Manitoba, Winnipeg, visits Arctic Research Centre
|Date||Tue 31 Jan|
|Time||14:00 — 15:00|
|Location||ARC, Ny Munkegade 114, Building 1540, meeting room 1540-020|
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. The study of sea ice bulk gas profiles (Ar, O2 and N2) using gas chromatography and new nondestructive X-ray computed tomography provided new results on gas dynamics, including the characterization of air volume fraction and controlling factors for gas entrapment and transport in first year sea ice.
According to our results, the vertical distribution of gas in first year sea ice is a function of (i) the physical condition at the ice-seawater interface and (ii) nucleation processes occurring either in the bottom layer, within the ice itself or at the ice-atmosphere interface. Once incorporated within the ice, gas can be further redistributed or released to the underlying seawater and to the above atmosphere by diffusion transport, convective transport, and buoyant transport. Convective transport (i.e. brine drainage) expels dissolved gas into underlying seawater, diffusion transport redistributes dissolved gases along a concentration gradient and governs the flux of gas at the sea ice-atmosphere interface, and buoyant transport causes the upward migration of bubbles, which could ultimately lead to a release of gas to the atmosphere given that the brine is sufficiently connected.
Results from this work are a valuable addition to limited studies available on gas content dynamics in sea ice, and provides a new methodology for the interpretation and characterization of sea ice porosity as well as new knowledge for sea ice modeling.
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