Speckle tracking of synthetic aperture RADAR imagery (Radarsat-1/2, ALOS PALSAR) and feature tracking of optical (Landsat-7 ETM+) imagery is used to determine the entire surface velocity structure of the major ice masses of the Canadian High Arctic in 2000, 2010-2015 and for select tidewater terminating glaciers from 1999-2010. At the termini of tidewater glaciers, surface ice velocities are combined with measured/modelled ice thicknesses to derive an estimate of mass loss via dynamic (iceberg) discharge. The total dynamic discharge for the ice masses of the southern Canadian Arctic Archipelago (SCAA: Baffin and Bylot Islands) is between ~17 and 180 Mt a-1 (0.017 to 0.180 Gt a-1) for the period 2007-2011, compared to a dynamic discharge of ~2.47 ± 0.88 Gt a-1 for the northern Canadian Arctic Archipelago (NCAA: Devon, Ellesmere, Axel Heiberg Islands) for the period 2011-2015. A comparison of these values with rates of mass loss via climatic mass balance (surface melt and runoff) indicates that dynamic discharge accounted for ~3.1% of total ablation for the NCAA in 2012 and ~0.11% of total ablation in the SCAA between 2007 and 2010. This reveals that total ablation in the Canadian Arctic is currently dominated by surface melt and runoff.
The glacier velocity dataset provides the most comprehensive record of ice motion and dynamic discharge in the Canadian Arctic to date and reveals a large degree of variability in glacier motion within the region over the last ~15 years. Most of the major glaciers in the NCAA have decelerated and their resultant dynamic discharge has decreased over the observation period, which is largely attributed to cyclical phases attributed to surging and pulsing. On pulse-type glaciers, variation in ice motion is largely confined to regions where the bed is located below sea level. A notable departure from the overall trend of regional velocity slowdown is the widespread acceleration of the Trinity and Wykeham Glaciers of the Prince of Wales Icefield (the largest glacier complex in the Canadian Arctic), which cannot be explained by surge or pulse mechanisms. The increased discharge from these two glaciers nearly compensates (within error) for the decrease in iceberg discharge from other glaciers across the study region and indicates that total dynamic discharge from the Canadian Arctic can be sensitive to the variations of ice flow of just a few glaciers.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/33180 |
| Date | January 2015 |
| Creators | Van Wychen, Wesley |
| Contributors | Copland, Luke, Burgess, David |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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