Differential impact of isolated topographic bumps on ice sheet flow and subglacial processes
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Published:2023-06-22
Issue:6
Volume:17
Page:2477-2486
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ISSN:1994-0424
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Container-title:The Cryosphere
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language:en
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Short-container-title:The Cryosphere
Author:
McKenzie Marion A.ORCID, Miller Lauren E.ORCID, Slawson Jacob S., MacKie Emma J., Wang ShujieORCID
Abstract
Abstract. Topographic highs (“bumps”) across glaciated landscapes have the
potential to temporarily slow ice sheet flow or, conversely, accelerate ice
flow through subglacial strain heating and meltwater production. Isolated
bumps of variable size across the deglaciated landscape of the Cordilleran
Ice Sheet (CIS) of Washington State present an opportunity to study the
influence of topographic highs on ice–bed interactions and ice flow
organization. This work utilizes semi-automatic mapping techniques of
subglacial bedforms to characterize the morphology of streamlined subglacial
bedforms including elongation, surface relief, and orientation, all of which
provide insight into subglacial processes during post-Last Glacial Maximum
deglaciation. We identify a bump-size threshold of several cubic kilometers
– around 4.5 km3 – in which bumps larger than this size will
consistently and significantly disrupt both ice flow organization and
subglacial sedimentary processes, which are fundamental to the genesis of
streamlined subglacial bedforms. Additionally, sedimentary processes are
persistent and well developed downstream of bumps, as reflected by enhanced
bedform elongation and reduced surface relief, likely due to increased
availability and production of subglacial sediment and meltwater. While
isolated topography plays a role in disrupting ice flow, larger bumps have a
greater disruption to ice flow organization, while bumps below the
identified threshold seem to have little effect on ice and subglacial
processes. The variable influence of isolated topographic bumps on ice flow
of the CIS has significant implications for outlet glaciers of the Greenland
Ice Sheet (GrIS) due to similarities in regional topography, where local
bumps are largely unresolved.
Publisher
Copernicus GmbH
Subject
Earth-Surface Processes,Water Science and Technology
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