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Ice surface temperature, albedo, and surface elevation change of glaciers and ice caps of the Queen Elizabeth Islands, Nunavut, Canada, 1995-2015.

  • Author / Creator
    Mortimer, Colleen A
  • Inter-annual variability in glacier and ice cap surface mass balance in the Queen Elizabeth Islands (QEI), Arctic Canada, is driven primarily by variability in summer melt. Mean summer (June-August) QEI glacier surface temperatures (LSTs) and shortwave broadband black-sky surface albedo (BSA) are determined from NASA’s Moderate Resolution Spectroradiometer (MODIS) for the period 2000(01)-2015 and provide the first near-complete picture of LST and BSA change for all glacier covered surfaces in the QEI. Between 2000 and 2015, mean summer LSTs increased at an average rate of 0.06 ± 0.04 °C yr-1, for a total increase of nearly 1°C. Most of this surface warming occurred between 2007 and 2012 when mean summer near-surface (2 m) and upper-air (700 hPa) temperatures were 1.0-1.2°C higher than the 1948-2015 mean. Over a similar period (2001-2015), the mean summer BSA for glaciated surfaces south of 80°N decreased by 0.057. Overall the 15-year record of mean summer BSA is negatively correlated (r = -0.71, p<0.2) with the 15 year record of mean summer LST, although local clusters of positive correlations were observed at high elevations in eastern Ellesmere Island. The observed positive ice-albedo feedback accelerates rates of melt and mass loss, and repeat airborne laser altimetry measurements show widespread thinning (surface lowering) across glaciated surfaces in the QEI since 1995. Rates of thinning, averaged for 50 m elevation bins, were more than three times larger from 2005/06 to 2012/14 than during the previous two pentads. Comparisons of dh/dt with MODIS-derived mean summer LST and BSA measurements and surface longitudinal strain rates, computed from RADARSAT- and LANDSAT -derived surface velocities for the period 2000-2012/14, indicate that QEI surface elevation changes were driven primarily by changes in climate except along most fast-flowing outlet glaciers where ice dynamics appear to have been a dominant forcing on observed dh/dt.

  • Subjects / Keywords
  • Graduation date
    2017-11:Fall 2017
  • Type of Item
    Thesis
  • Degree
    Doctor of Philosophy
  • DOI
    https://doi.org/10.7939/R39S1M02C
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
    English
  • Institution
    University of Alberta
  • Degree level
    Doctoral
  • Department
    • Department of Earth and Atmospheric Sciences
  • Supervisor / co-supervisor and their department(s)
    • Dr. Martin Sharp
  • Examining committee members and their departments
    • St. Louis, Vincent (Biology)
    • Kavanaugh, Jeffrey (EAS)
    • Rivard, Benoit (EAS)
    • Abdalati, Waleed (University of Colorado)
    • Sharp, Martin (EAS)