The role of near-terminus conditions in the ice-flow speed of Upernavik Isstrøm in northwest Greenland

Kelsey M. Voss; Karen E. Alley; David A. Lilien; Dorthe Dahl-Jensen

doi:10.1017/aog.2023.76

Annals of Glaciology ()

The role of near-terminus conditions in the ice-flow speed of Upernavik Isstrøm in northwest Greenland

Kelsey M. Voss,
Karen E. Alley,
David A. Lilien,
Dorthe Dahl-Jensen

Affiliations

Kelsey M. Voss: ORCiD; The Centre for Earth Observation Science, University of Manitoba Clayton H. Riddell Faculty of Environment, Earth, and Resources, Winnipeg, MB, Canada Department of Environment and Geography, University of Manitoba Clayton H. Riddell Faculty of Environment, Earth, and Resources, Winnipeg, MB, Canada Department of Environment and Geography, The University of Manitoba, Winnipeg, MB, Canada
Karen E. Alley: ORCiD; The Centre for Earth Observation Science, University of Manitoba Clayton H. Riddell Faculty of Environment, Earth, and Resources, Winnipeg, MB, Canada Department of Environment and Geography, University of Manitoba Clayton H. Riddell Faculty of Environment, Earth, and Resources, Winnipeg, MB, Canada Department of Environment and Geography, The University of Manitoba, Winnipeg, MB, Canada
David A. Lilien: ORCiD; The Centre for Earth Observation Science, University of Manitoba Clayton H. Riddell Faculty of Environment, Earth, and Resources, Winnipeg, MB, Canada Department of Environment and Geography, University of Manitoba Clayton H. Riddell Faculty of Environment, Earth, and Resources, Winnipeg, MB, Canada Department of Environment and Geography, The University of Manitoba, Winnipeg, MB, Canada
Dorthe Dahl-Jensen: ORCiD; The Centre for Earth Observation Science, University of Manitoba Clayton H. Riddell Faculty of Environment, Earth, and Resources, Winnipeg, MB, Canada Department of Environment and Geography, University of Manitoba Clayton H. Riddell Faculty of Environment, Earth, and Resources, Winnipeg, MB, Canada Department of Environment and Geography, The University of Manitoba, Winnipeg, MB, Canada Niels Bohr Institute, University of Copenhagen, Kobenhavn, Denmark

DOI: https://doi.org/10.1017/aog.2023.76

Abstract

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Upernavik Isstrøm, the largest contributor to sea-level rise in northwest Greenland, has experienced complex and contrasting ice-flow-speed changes across its five outlets over the last two decades. In this study, we present a detailed remote-sensing analysis of the ice dynamics at Upernavik's outlets from 2000 to 2021 to evaluate the details of these changes. Previous research suggested that the presence or absence of floating ice tongues strongly influences Upernavik's ice dynamics. We use several lines of evidence to document the presence of floating ice tongues, and find that, while several outlets experienced ice-tongue formation and/or loss during the study period, these changes do not explain observed fluctuations in ice-flow velocity. Further exploration of ice-dynamic forcings using a flowline model suggests that changes in basal slipperiness near the terminus have a strong impact on upstream ice dynamics and can explain the velocity variations. Our results suggest that speed fluctuations at Upernavik's outlets may be seasonally and interannually controlled by bed conditions near the terminus, and highlight the need for further research on the influence of basal conditions on complex tidewater glacier dynamics.

Published in Annals of Glaciology

ISSN: 0260-3055 (Print); 1727-5644 (Online)
Publisher: Cambridge University Press
Country of publisher: United Kingdom
LCC subjects: Science: Physics: Meteorology. Climatology
Website: https://www.cambridge.org/core/journals/annals-of-glaciology

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