Velocity structure, flow instability and mass flux on a large Arctic ice cap from satellite radar interferometry
Satellite radar interferometry allows calculation of the ice-surface velocity distribution throughout the largest ice cap in the Eurasian Arctic: Austfonna in eastern Svalbard. Data on ice-cap velocity structure show strong spatial variations observed in unprecedented detail. Ice-cap drainage basins...
Main Authors: | , , , |
---|---|
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
ELSEVIER SCIENCE BV
1999
|
Subjects: | |
Online Access: | http://discovery.ucl.ac.uk/113310/ |
id |
ftucl:oai:eprints.ucl.ac.uk.OAI2:113310 |
---|---|
record_format |
openpolar |
spelling |
ftucl:oai:eprints.ucl.ac.uk.OAI2:113310 2023-05-15T15:00:30+02:00 Velocity structure, flow instability and mass flux on a large Arctic ice cap from satellite radar interferometry Dowdeswell, JA Unwin, B Nuttall, AM Wingham, DJ 1999-04-15 http://discovery.ucl.ac.uk/113310/ unknown ELSEVIER SCIENCE BV EARTH PLANET SC LETT , 167 (3-4) 131 - 140. (1999) satellite measurements interferometry Svalbard ice caps ice movement unsteady flow mass movements velocity structure SURGE-TYPE GLACIER SHEET MOTION VARIEGATED GLACIER DRAINAGE-BASIN GREENLAND DYNAMICS PHASE NORDAUSTLANDET ALASKA Article 1999 ftucl 2016-01-15T02:50:03Z Satellite radar interferometry allows calculation of the ice-surface velocity distribution throughout the largest ice cap in the Eurasian Arctic: Austfonna in eastern Svalbard. Data on ice-cap velocity structure show strong spatial variations observed in unprecedented detail. Ice-cap drainage basins have clearly defined fast-flowing units with marked shear margins at the surface, associated with troughs in the subglacial bedrock identified from 60 MHz ice-penetrating radar. Interferometric measurements show that the velocity structure in most ice-cap drainage basins remained stable over a 2-year period. Unexpectedly, however; in the basin where surface velocities were the highest on the ice cap, at 140 m yr(-1) in winter 1992, the flow rate had halved by winter 1994. A time series of visible-band Landsat imagery shows that this basin was relatively inactive between 1973 and 1991, but had a distinctly disturbed surface in 1993. This flow instability was initiated after summer 1991 and is likely to be a glacier surge or mini-surge, demonstrating the increasing diversity of motion events revealed by radar interferometry. Mass flux through this basin, calculated using ice velocity and thickness data, was 0.1 km(3) yr(-1) in 1992, an increase of up to two orders of magnitude over that prior to flow instability. Calculated balance velocity is an order of magnitude less than the interferometrically derived velocity, implying that the flow rates observed for the fast-flowing unit cannot be sustained under the present climate. (C) 1999 Elsevier Science B.V. All rights reserved. Article in Journal/Newspaper Arctic Austfonna glacier glacier glacier Greenland Ice cap Nordaustlandet Svalbard Alaska University College London: UCL Discovery Arctic Austfonna ENVELOPE(24.559,24.559,79.835,79.835) Greenland Nordaustlandet ENVELOPE(22.400,22.400,79.800,79.800) Svalbard |
institution |
Open Polar |
collection |
University College London: UCL Discovery |
op_collection_id |
ftucl |
language |
unknown |
topic |
satellite measurements interferometry Svalbard ice caps ice movement unsteady flow mass movements velocity structure SURGE-TYPE GLACIER SHEET MOTION VARIEGATED GLACIER DRAINAGE-BASIN GREENLAND DYNAMICS PHASE NORDAUSTLANDET ALASKA |
spellingShingle |
satellite measurements interferometry Svalbard ice caps ice movement unsteady flow mass movements velocity structure SURGE-TYPE GLACIER SHEET MOTION VARIEGATED GLACIER DRAINAGE-BASIN GREENLAND DYNAMICS PHASE NORDAUSTLANDET ALASKA Dowdeswell, JA Unwin, B Nuttall, AM Wingham, DJ Velocity structure, flow instability and mass flux on a large Arctic ice cap from satellite radar interferometry |
topic_facet |
satellite measurements interferometry Svalbard ice caps ice movement unsteady flow mass movements velocity structure SURGE-TYPE GLACIER SHEET MOTION VARIEGATED GLACIER DRAINAGE-BASIN GREENLAND DYNAMICS PHASE NORDAUSTLANDET ALASKA |
description |
Satellite radar interferometry allows calculation of the ice-surface velocity distribution throughout the largest ice cap in the Eurasian Arctic: Austfonna in eastern Svalbard. Data on ice-cap velocity structure show strong spatial variations observed in unprecedented detail. Ice-cap drainage basins have clearly defined fast-flowing units with marked shear margins at the surface, associated with troughs in the subglacial bedrock identified from 60 MHz ice-penetrating radar. Interferometric measurements show that the velocity structure in most ice-cap drainage basins remained stable over a 2-year period. Unexpectedly, however; in the basin where surface velocities were the highest on the ice cap, at 140 m yr(-1) in winter 1992, the flow rate had halved by winter 1994. A time series of visible-band Landsat imagery shows that this basin was relatively inactive between 1973 and 1991, but had a distinctly disturbed surface in 1993. This flow instability was initiated after summer 1991 and is likely to be a glacier surge or mini-surge, demonstrating the increasing diversity of motion events revealed by radar interferometry. Mass flux through this basin, calculated using ice velocity and thickness data, was 0.1 km(3) yr(-1) in 1992, an increase of up to two orders of magnitude over that prior to flow instability. Calculated balance velocity is an order of magnitude less than the interferometrically derived velocity, implying that the flow rates observed for the fast-flowing unit cannot be sustained under the present climate. (C) 1999 Elsevier Science B.V. All rights reserved. |
format |
Article in Journal/Newspaper |
author |
Dowdeswell, JA Unwin, B Nuttall, AM Wingham, DJ |
author_facet |
Dowdeswell, JA Unwin, B Nuttall, AM Wingham, DJ |
author_sort |
Dowdeswell, JA |
title |
Velocity structure, flow instability and mass flux on a large Arctic ice cap from satellite radar interferometry |
title_short |
Velocity structure, flow instability and mass flux on a large Arctic ice cap from satellite radar interferometry |
title_full |
Velocity structure, flow instability and mass flux on a large Arctic ice cap from satellite radar interferometry |
title_fullStr |
Velocity structure, flow instability and mass flux on a large Arctic ice cap from satellite radar interferometry |
title_full_unstemmed |
Velocity structure, flow instability and mass flux on a large Arctic ice cap from satellite radar interferometry |
title_sort |
velocity structure, flow instability and mass flux on a large arctic ice cap from satellite radar interferometry |
publisher |
ELSEVIER SCIENCE BV |
publishDate |
1999 |
url |
http://discovery.ucl.ac.uk/113310/ |
long_lat |
ENVELOPE(24.559,24.559,79.835,79.835) ENVELOPE(22.400,22.400,79.800,79.800) |
geographic |
Arctic Austfonna Greenland Nordaustlandet Svalbard |
geographic_facet |
Arctic Austfonna Greenland Nordaustlandet Svalbard |
genre |
Arctic Austfonna glacier glacier glacier Greenland Ice cap Nordaustlandet Svalbard Alaska |
genre_facet |
Arctic Austfonna glacier glacier glacier Greenland Ice cap Nordaustlandet Svalbard Alaska |
op_source |
EARTH PLANET SC LETT , 167 (3-4) 131 - 140. (1999) |
_version_ |
1766332595228901376 |