The cooling signature of basal crevasses in a hard-bedded region of the Greenland Ice Sheet
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Published:2021-02-19
Issue:2
Volume:15
Page:897-907
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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:
McDowell Ian E.ORCID, Humphrey Neil F., Harper Joel T., Meierbachtol Toby W.ORCID
Abstract
Abstract. Temperature sensors installed in a grid of nine full-depth boreholes
drilled in the southwestern ablation zone of the Greenland Ice Sheet
recorded cooling in discrete sections of ice over time within the lowest
third of the ice column in most boreholes. Rates of temperature change
outpace cooling expected from vertical conduction alone. Additionally,
observed temperature profiles deviate significantly from the site-average
thermal profile that is shaped by all thermomechanical processes upstream.
These deviations imply recent, localized changes to the basal thermal state
in the boreholes. Although numerous heat sources exist to add energy and
warm ice as it moves from the central divide towards the margin such as
strain heat from internal deformation, latent heat from refreezing
meltwater, and the conduction of geothermal heat across the ice–bedrock
interface, identifying heat sinks proves more difficult. After eliminating
possible mechanisms that could cause cooling, we find that the observed
cooling is a manifestation of previous warming in near-basal ice. Thermal
decay after latent heat is released from freezing water in basal crevasses
is the most likely mechanism resulting in the transient evolution of
temperature and the vertical thermal structure observed at our site. We
argue basal crevasses are a viable englacial heat source in the basal ice of
Greenland's ablation zone and may have a controlling influence on the
temperature structure of the near-basal ice.
Funder
Office of Polar Programs
Publisher
Copernicus GmbH
Subject
Earth-Surface Processes,Water Science and Technology
Reference44 articles.
1. Andrews, L. C., Catania, G. A., Hoffman, M. J., Gulley, J. D., Lüthi, M.
P., Ryser, C., Hawley, R. L., and Neumann, T. A.: Direct observations of
evolving subglacial drainage beneath the Greenland Ice Sheet, Nature,
514, 80–83, https://doi.org/10.1038/nature13796, 2014. 2. Brown, J., Harper, J., and Humphrey, N.: Liquid water content in ice estimated through a full-depth ground radar profile and borehole measurements in western Greenland, The Cryosphere, 11, 669–679, https://doi.org/10.5194/tc-11-669-2017, 2017. 3. Carslaw, H. S. and Jaeger, J. C.: Conduction of Heat in Solids, 2nd edition,
Clarendon Press, Oxford, England, 1959. 4. Catania, G. A. and Neumann, T. A.: Persistent englacial drainage features in
the Greenland Ice Sheet, Geophys. Res. Lett., 37, L02501, https://doi.org/10.1029/2009GL041108, 2010. 5. Catania, G. A., Conway, H., Raymond, C. F., and Scambos, T. A.: Surface
morphology and internal layer stratigraphy in the downstream end of Kamb Ice
Stream, West Antarctica, J. Glaciol., 51, 423–431,
https://doi.org/10.3189/172756505781829142, 2005.
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