Seasonal and interannual variabilities in terminus position, glacier velocity, and surface elevation at Helheim and Kangerlussuaq Glaciers from 2008 to 2016

Seasonal and interannual variabilities in terminus position, glacier velocity, and surface elevation at Helheim and Kangerlussuaq Glaciers from 2008 to 2016

The dynamic response of Greenland tidewater glaciers to oceanic and atmospheric change has varied both spatially and temporally. While some of this variability is likely related to regional climate signals, glacier geometry also appears to be important. In this study, we investigated the environment...

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Bibliographic Details
Published in:Journal of geophysical research. Earth surface Vol. 122; no. 9; pp. 1635 - 1652
Main Authors: Kehrl, L. M., Joughin, I., Shean, D. E., Floricioiu, D., Krieger, L.
Format: Journal Article
Language:English
Published: Washington Blackwell Publishing Ltd 01-09-2017
Subjects:
Dynamic response
Elevation
Evolution
Floating ice
Glacier tongues
Glacier velocities
Glaciers
Greenland
Ice
Ice calving
ice dynamics
Ice shelves
iceberg calving
Lubrication
outlet glaciers
Position measurement
Regional climates
remote sensing
Satellites
Seasonal variability
Seasonal variation
Seasonal variations
Studies
Summer
Surface velocity
Thinning
Tidewater
Velocity
Greenland
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Summary:The dynamic response of Greenland tidewater glaciers to oceanic and atmospheric change has varied both spatially and temporally. While some of this variability is likely related to regional climate signals, glacier geometry also appears to be important. In this study, we investigated the environmental and geometric controls on the seasonal and interannual evolution of Helheim and Kangerlussuaq Glaciers, Southeast Greenland, from 2008 to 2016, by combining year‐round, satellite measurements of terminus position, glacier velocity, and surface elevation. While Helheim remained relatively stable with a lightly grounded terminus over this time period, Kangerlussuaq continued to lose mass as its grounding line retreated into deeper water. By summer 2011, Kangerlussuaq's grounding line had retreated into shallower water, and the glacier had an ~5 km long floating ice tongue. We also observed seasonal variations in surface velocity and elevation at both glaciers. At Helheim, seasonal speedups and dynamic thinning occurred in the late summer when the terminus was most retreated. At Kangerlussuaq, we observed summer speedups due to surface‐melt‐induced basal lubrication and winter speedups due to ice‐shelf retreat. We suggest that Helheim and Kangerlussuaq behaved differently on a seasonal timescale due to differences in the spatial extent of floating ice near their termini, which affected iceberg‐calving behavior. Given that seasonal speedups and dynamic thinning can alter this spatial extent, these variations may be important for understanding the long‐term evolution of these and other Greenland tidewater glaciers. Key Points We produced a year‐round record of glacier velocity and surface elevation to investigate dynamic changes at Helheim and Kangerlussuaq Seasonal speedups and dynamic thinning occurred at both glaciers but through different processes Seasonal dynamic thinning altered the spatial extent of floating ice near the terminus, which affected iceberg‐calving behavior
ISSN:2169-9003
2169-9011
DOI:10.1002/2016JF004133