Physical conditions of fast glacier flow: 1. measurements from boreholes drilled to the bed of Store Glacier, West Greenland
Marine-terminating outlet glaciers of the Greenland ice sheet make significant contributions to global sea level rise, yet the conditions that facilitate their fast flow remain poorly constrained owing to a paucity of data. We drilled and instrumented seven boreholes on Store Glacier, Greenland, to...
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ftunivcam:oai:www.repository.cam.ac.uk:1810/270570 2024-01-14T10:01:37+01:00 Physical conditions of fast glacier flow: 1. measurements from boreholes drilled to the bed of Store Glacier, West Greenland Doyle, SH Hubbard, B Christoffersen, Poul Young, TJ Hofstede, C Bougamont, MH Box, JE Hubbard, A 2018 application/pdf https://www.repository.cam.ac.uk/handle/1810/270570 https://doi.org/10.17863/CAM.17485 eng eng Wiley-Blackwell https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017JF004529 Journal of Geophysical Research https://doi.org/10.6084/m9.figshare.5745294 https://www.repository.cam.ac.uk/handle/1810/270570 doi:10.17863/CAM.17485 Attribution 4.0 International http://creativecommons.org/licenses/by/4.0/ Greenland ice sheet hydrology dynamics borehole sediment Article 2018 ftunivcam https://doi.org/10.17863/CAM.1748510.6084/m9.figshare.5745294 2023-12-21T23:27:26Z Marine-terminating outlet glaciers of the Greenland ice sheet make significant contributions to global sea level rise, yet the conditions that facilitate their fast flow remain poorly constrained owing to a paucity of data. We drilled and instrumented seven boreholes on Store Glacier, Greenland, to monitor subglacial water pressure, temperature, electrical conductivity and turbidity along with englacial ice temperature and deformation. These observations were supplemented by surface velocity and meteorological measurements to gain insight into the conditions and mechanisms of fast glacier flow. Located 30 km from the calving front, each borehole drained rapidly on attaining 600m depth indicating a direct connection with an active subglacial hydrological system. Persistently high subglacial water pressures indicate low effective pressure (180 - 280 kPa), with small amplitude variations correlated with notable peaks in surface velocity driven by the diurnal melt cycle and longer periods of melt and rainfall. The englacial deformation profile determined from borehole tilt measurements indicates that 63-71% of total ice motion occurred at the bed, with the remaining 29-37% predominantly attributed to enhanced deformation in the lowermost 50-100 m of the ice column. We interpret this lowermost 100m to be formed of warmer, pre-Holocene ice overlying a thin (0-8m) layer of temperate basal ice. Our observations are consistent with a spatially-extensive and persistently-inefficient subglacial drainage system that we hypothesize comprises drainage both at the ice-sediment interface and through subglacial sediments. This configuration has similarities to that interpreted beneath dynamically-analogous Antarctic ice streams, Alaskan tidewater glaciers, and glaciers in surge. This research was funded by UK National Environment Research Council grants NE/K006126 and NE/K005871/1 and an Aberystwyth University Capital Equipment grant to B. H. A. H. gratefully acknowledges support from the BBC's Operation Iceberg program for ... Article in Journal/Newspaper Antarc* Antarctic glacier Greenland Ice Sheet Iceberg* Tidewater Apollo - University of Cambridge Repository Antarctic Greenland |
institution |
Open Polar |
collection |
Apollo - University of Cambridge Repository |
op_collection_id |
ftunivcam |
language |
English |
topic |
Greenland ice sheet hydrology dynamics borehole sediment |
spellingShingle |
Greenland ice sheet hydrology dynamics borehole sediment Doyle, SH Hubbard, B Christoffersen, Poul Young, TJ Hofstede, C Bougamont, MH Box, JE Hubbard, A Physical conditions of fast glacier flow: 1. measurements from boreholes drilled to the bed of Store Glacier, West Greenland |
topic_facet |
Greenland ice sheet hydrology dynamics borehole sediment |
description |
Marine-terminating outlet glaciers of the Greenland ice sheet make significant contributions to global sea level rise, yet the conditions that facilitate their fast flow remain poorly constrained owing to a paucity of data. We drilled and instrumented seven boreholes on Store Glacier, Greenland, to monitor subglacial water pressure, temperature, electrical conductivity and turbidity along with englacial ice temperature and deformation. These observations were supplemented by surface velocity and meteorological measurements to gain insight into the conditions and mechanisms of fast glacier flow. Located 30 km from the calving front, each borehole drained rapidly on attaining 600m depth indicating a direct connection with an active subglacial hydrological system. Persistently high subglacial water pressures indicate low effective pressure (180 - 280 kPa), with small amplitude variations correlated with notable peaks in surface velocity driven by the diurnal melt cycle and longer periods of melt and rainfall. The englacial deformation profile determined from borehole tilt measurements indicates that 63-71% of total ice motion occurred at the bed, with the remaining 29-37% predominantly attributed to enhanced deformation in the lowermost 50-100 m of the ice column. We interpret this lowermost 100m to be formed of warmer, pre-Holocene ice overlying a thin (0-8m) layer of temperate basal ice. Our observations are consistent with a spatially-extensive and persistently-inefficient subglacial drainage system that we hypothesize comprises drainage both at the ice-sediment interface and through subglacial sediments. This configuration has similarities to that interpreted beneath dynamically-analogous Antarctic ice streams, Alaskan tidewater glaciers, and glaciers in surge. This research was funded by UK National Environment Research Council grants NE/K006126 and NE/K005871/1 and an Aberystwyth University Capital Equipment grant to B. H. A. H. gratefully acknowledges support from the BBC's Operation Iceberg program for ... |
format |
Article in Journal/Newspaper |
author |
Doyle, SH Hubbard, B Christoffersen, Poul Young, TJ Hofstede, C Bougamont, MH Box, JE Hubbard, A |
author_facet |
Doyle, SH Hubbard, B Christoffersen, Poul Young, TJ Hofstede, C Bougamont, MH Box, JE Hubbard, A |
author_sort |
Doyle, SH |
title |
Physical conditions of fast glacier flow: 1. measurements from boreholes drilled to the bed of Store Glacier, West Greenland |
title_short |
Physical conditions of fast glacier flow: 1. measurements from boreholes drilled to the bed of Store Glacier, West Greenland |
title_full |
Physical conditions of fast glacier flow: 1. measurements from boreholes drilled to the bed of Store Glacier, West Greenland |
title_fullStr |
Physical conditions of fast glacier flow: 1. measurements from boreholes drilled to the bed of Store Glacier, West Greenland |
title_full_unstemmed |
Physical conditions of fast glacier flow: 1. measurements from boreholes drilled to the bed of Store Glacier, West Greenland |
title_sort |
physical conditions of fast glacier flow: 1. measurements from boreholes drilled to the bed of store glacier, west greenland |
publisher |
Wiley-Blackwell |
publishDate |
2018 |
url |
https://www.repository.cam.ac.uk/handle/1810/270570 https://doi.org/10.17863/CAM.17485 |
geographic |
Antarctic Greenland |
geographic_facet |
Antarctic Greenland |
genre |
Antarc* Antarctic glacier Greenland Ice Sheet Iceberg* Tidewater |
genre_facet |
Antarc* Antarctic glacier Greenland Ice Sheet Iceberg* Tidewater |
op_relation |
https://doi.org/10.6084/m9.figshare.5745294 https://www.repository.cam.ac.uk/handle/1810/270570 doi:10.17863/CAM.17485 |
op_rights |
Attribution 4.0 International http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.17863/CAM.1748510.6084/m9.figshare.5745294 |
_version_ |
1788067377654530048 |