Surface features of the cold/temperate transition zone at White Glacier terminus, Axel Heiberg Island, Nunavut.
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Authors
Lee, Jeremiah
Date
Type
thesis
Language
eng
Keyword
Glaciology , Photogrammetry , Arctic Glaciers , Structural Glaciology , Remote Sensing , Polythermal Glaciers
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Abstract
The historical records of White Glacier (WG), a polythermal valley glacier found in northern Nunavut, Canada, are used alongside modern structural models and orthomosaics produced from Structure from Motion photogrammetry to assess change in the terminus region. Recognizing the surface expression of terminus change contributes to the understanding of ice dynamics and improves the potential for regional glacier assessment by providing target features to be interpreted through remote sensing methods.
Elevation models from 1960, 2011, 2018 and 2019 of various origins were homogenized. The geodetic mass balance of the terminus region was measured from co-registered digital elevation models (DEMs) and found to have contributed 21 \% of the total volume loss of WG between 1960 – 2014, while only consisting of 7 \% of the total glacier surface area, consistent with past findings. Surface structures at WG terminus were assessed using nadir imagery captured between 1960 – 2019. Signs of decreasing ice dynamics were observed, indicative of a stagnating terminus experiencing retreat conditions. Compressive strain is thought to reactivate crevasse traces as they transit the terminus icefall, leading to the formation of novel arcuate band features through recrystallization.
Surveys of reflective prisms and optical feature tracking results between 2018 – 2019 were used to measure modern ice velocity and strain rate components, while DEMs and interpolated mass balance measurements were used to calculate ice emergence velocity between 1960 – 2018. Early emergence indicates that ice uplift occurred in the terminus lobe from compressive strain increasing with distance down-glacier. Annual strain indicates that modern ice flow is less obstructed above the terminus icefall, and enters a zone of moderate compressional deformation in the terminus lobe below, while the magnitude of emergence has decreased. This difference, paired with a reduced temperate ice extent measured in comparison to the 1970s, is possibly due to limited basal motion permitted through efficient sub-glacial hydrologic channels. The persistence of the temperate ice region is thought to have become increasingly dependent on the influx meltwater to the glacier bed.
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution 3.0 United States