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Velocity Variations of the Kaskawulsh Glacier, Yukon Territory, 2009-2011

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Velocity Variations of the Kaskawulsh Glacier, Yukon Territory, 2009-2011 Velocity Variations of the Kaskawulsh Glacier, Yukon Territory, 2009-2011 Samantha Darling Thesis submitted to the Faculty of Graduate and Postdoctoral Studies in partial fulfillment of the requirements for the MSc Degree in Physical Geography Department of Geography Faculty of Arts University of Ottawa Supervisor: Dr. Luke Copland (University of Ottawa) Thesis Committee: Dr. Laurence Gray (Canada Centre for Remote Sensing) Dr. André Viau (University of Ottawa) ©Samantha Darling, Ottawa, Canada, 2012 Abstract Laser altimetry and satellite gravity surveys indicate that the St Elias Icefields are currently losing mass and are among the largest non-polar sea level contributors in the world. However, a poor understanding of glacier dynamics in the region is a major hurdle in evaluating regional variations in ice motion and the relationship between changing surface conditions and ice flux. This study combines in-situ dGPS measurements and advanced Radarsat-2 (RS-2) processing techniques to determine daily and seasonal ice velocities for the Kaskawulsh Glacier from summer 2009 to summer 2011. Three permanent dGPS stations were installed along the centreline of the glacier in 2009, with an additional permanent station on the South Arm in 2010. The Precise Point Positioning (PPP) method is used to process the dGPS data using high accuracy orbital reconstruction. RS-2 imagery was acquired on a 24-day cycle from January to March 2010, and from October to March 2010- 2011 in a combination of ultra-fine and fine beam modes. Seasonal velocity regimes are readily identifiable in the dGPS results, with distinct variations in both horizontal velocity and vertical motion. The Spring Regime consists of an annual peak in horizontal velocity that corresponds closely with the onset of the melt season and progresses up-glacier, following the onset of melt at each station. The Summer Regime sees variable horizontal velocity and vertical uplift, superimposed on a long-term decline in motion. The Fall Regime sees a gradual slowing at all stations with little variation in horizontal velocity or vertical position. Rapid but short accelerations lasting up to 10 days were seen in the Winter regimes in both 2010 and 2011, occurring at various times throughout each regime. These events initiated at the Upper Station and progress down- glacier at propagation speeds up to 16,380 m day-1 and were accompanied by vertical uplift lasting for similar periods. Three velocity maps, one from the winter of 2010 and two from the fall/winter of 2011, produced from speckle tracking were validated by comparison with dGPS velocity, surface flow direction, and bedrock areas of zero motion, with an average velocity error of 2.0% and average difference in orientation of 4.3º. ii Acknowledgments Funding and resources for this project were provided by: Natural Sciences and Engineering Research Council Canadian Graduate Scholarship Association of Canadian Universities for Northern Studies Garfield Weston Award The Yukon Territorial Government’s Yukon Grant Natural Sciences and Engineering Research Council Northern Research Internship Program The Canadian Space Agency’s SOAR-E program (project #5015) Parks Canada (especially C.Wong and the wardens of the Kluane National Park and Reserve and J. Poitevin for providing Radarsat-2 images) CryoEx Northern Scientific Training Program Polar Continental Shelf Program Canada Foundation for Innovation Natural Sciences and Engineering Research Council Discovery Grant Ontario Research Fund Kluane First Nation Kluane Lake Research Station I would also like to thank all of those folks who helped me in the field, who are too numerous to count, as well as the staff of Kluane Helicopters and Trans North Helicopters. I would like to thank B. Danielson for providing the construction plans for the dGPS stations and C. Zdanowicz of the Geological Survey of Canada for providing additional weather data. I would like to thank my friends J. Cao, S. Chow and K. Fong for reminding me to take care of myself, and doing so for me when I forgot, along with J. Tondu and J.Neilson, for being my intercollegiate support system and being there during the hard times. Thanks must also go to S. Thériault at the Department of Geography for all of her support and enthusiasm. I would like to thank Dr. A. Viau for taking the time to provide insightful criticism and Dr. L. Gray for his patience and brilliance for the duration of the project. I would like to greatly acknowledge and thank W.VanWychen for his mentorship and guidance from the very beginning, and A.White for her patience and kindness through to the end, as well as the other members of the Laboratory for Cryospheric Research for their support throughout. I would especially like to thank my supervisor Dr. L.Copland for his patience and support, as well as the numerous opportunities he has provided and his willingness to let me return to the Yukon as much as possible. This project would not have been completed without the constant encouragement, love, and support of my entire family. Finally, I would like to thank the people of the Klehini Valley, for teaching me to believe in myself, humanity and the future. iii Table of Contents ABSTRACT ............................................................................................................................ II ACKNOWLEDGMENTS .................................................................................................... III TABLE OF CONTENTS ..................................................................................................... IV LIST OF FIGURES .............................................................................................................. VI LIST OF TABLES ................................................................................................................ IX CHAPTER 1 INTRODUCTION ........................................................................................... 1 1.1 GLACIER CHANGES IN ALASKA-YUKON ........................................................................... 3 1.2 STUDY OBJECTIVES .......................................................................................................... 5 1.3 THESIS STRUCTURE .......................................................................................................... 6 CHAPTER 2 BACKGROUND ............................................................................................ 11 2.1 GLACIER MOTION AND GLACIER THERMAL REGIMES ...................................................... 11 2.2 GLACIER HYDROLOGY .................................................................................................... 13 2.2.1 Surface meltwater migration .................................................................................. 13 2.2.2 Subglacial hydrology ............................................................................................. 14 2.3 BASAL GLACIER MOTION ................................................................................................ 15 2.4 STUDY AREA .................................................................................................................. 23 2.4.1 Regional weather patterns ..................................................................................... 23 2.4.2 The Kaskawulsh Glacier ........................................................................................ 24 2.4.3 The Kaskawulsh Glacier in the Holocene .............................................................. 25 2.4.4 The Slims River and the Kaskawulsh River ........................................................... 25 CHAPTER 3 METHODS..................................................................................................... 36 3.1 DIFFERENTIAL GPS ........................................................................................................ 36 3.2 THE PRECISE POINT POSITIONING METHOD .................................................................... 37 3.3 SECONDARY GROUND MEASUREMENTS .......................................................................... 40 3.4 REMOTE SENSING ........................................................................................................... 40 3.4.1 Speckle tracking theory .......................................................................................... 42 3.4.2 Potential sources of error ...................................................................................... 42 CHAPTER 4 RESULTS ....................................................................................................... 53 4.1 DGPS MEASUREMENTS .................................................................................................. 53 4.1.1 dGPS validation ..................................................................................................... 53 4.1.2 Seasonal Summary ................................................................................................. 54 4.1.3 2009-2010 (Year 1) ................................................................................................ 55 4.1.4 2010-2011 (Year 2) ................................................................................................ 56 4.2 SPECKLE TRACKING ....................................................................................................... 57 4.2.1 Validation of Remote Sensing Results .................................................................... 58 4.2.2 Velocity Results from Ultra-Fine Beam Imagery ..................................................
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