Differential impact of isolated topographic bumps on ice sheet flow and subglacial processes

Marion A. McKenzie, Lauren E. Miller, Jacob S. Slawson, Emma J. Mackie, Shujie Wang

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)2477-2486
Number of pages10
JournalCryosphere
Volume17
Issue number6
DOIs
StatePublished - Jun 22 2023

All Science Journal Classification (ASJC) codes

  • Water Science and Technology
  • Earth-Surface Processes

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