Ice Dynamics

Iken1968dataWhite Glacier hosts some of the earliest measurements of ice velocity fluctuations in the Arctic. The early work of Almut Iken at White Glacier1 2, of which the field demands were notably arduous, demonstrated for the first time that glacier velocities were correlated with basal water pressures beneath the ice. In addition to revolutionizing our understanding of glacier mechanics, these early observations are an invaluable foundation for us to observe how ice velocities have changed over the past half-century.

Differential GPS station at Wind profile, approximately 600 m a.s.l. Photo credit: L. Thomson
Differential GPS station at Wind profile, approximately 600 m a.s.l. Photo credit: L. Thomson

In the past five years, differential GPS stations have been installed at four locations on White Glacier where earlier ice velocities were made between 1960 and 1969. Preliminary results from this research suggest that the glacier is slowing down at each of these locations with an observed 5-40% decrease in annual displacement. This pattern that has been observed for other glaciers around the world as well3. We are also investigating short-term fluctuations in velocity
that are associated with hydrological events, such as the spring freshet, periods of above average melt rates, or the rapid drainage of ice-marginal lakes. Despite being a mostly-cold polythermal glacier4 (i.e. most of the ice is well below 0º C and frozen to underlying permafrost) White Glacier regularly demonstrates significant speed-up events in the spring and summer when the ice may move at >400% the normal background velocity.

 

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Leica Automatic Total Station in use at White Glacier, Summer 2016. Photo credit: L. Thomson

To study the ice dynamics with greater spatial coverage, we have installed a network of 25 prisms along the original “Anniversary Profile” studied by Almut Iken that we survey through the spring and summer months using an automated total station. This will enable us to better understand how these speed-up events impact ice motion at the glacier margins as well as along the glacier center-line.

 

 

 


 

  1. Iken, A. (1974), Velocity fluctuations of an arctic valley glacier, A study of the White Glacier, Axel Heiberg Island, Canadian Arctic Archipelago., Axel Heiberg Island Research Reports, Glaciology, No. 5, 123.
  2. Müller, F., and A. Iken (1973), Velocity fluctuations and water regime of Arctic valley
    glaciers, paper presented at Symposium on the Hydrology of Glaciers, de I’Association Internationale d’Hydrologie Scientifique, Cambridge, 7-13 September 1969.
  3. Heid, T., and A. Kaab (2012), Repeat optical satellite images reveal widespread and long term decrease in land-terminating glacier speeds, The Cryosphere, 6, 12.
  4. Blatter, H. (1987), On the thermal regime of an Arctic valley glacier: a study of White Glacier, Axel Heiberg Island, N.W.T., Canada, Journal of Glaciology, 33(114), 3.

Axel Heiberg Island, NU