Determination of the Surface and Bed Topography in Central Greenland
Abstract The surface and bottom topography of the central Greenland ice sheet was determined from airborne ice-radar soundings over a 180 km by 180 km grid centered on the 1974 “Summit” site (lat. 72°18′N., long. 37°55′W.), using the Technical University of Denmark 60 MHz ice radar. Over 6100 km of...
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Cambridge University Press (CUP)
1990
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crcambridgeupr:10.1017/s0022143000005505 2024-09-15T18:09:28+00:00 Determination of the Surface and Bed Topography in Central Greenland Hodge, Steven M. Wright, David L. Bradley, Jerry A. Jacobel, Robert W. Skou, Neils Vaughn, Bruce 1990 http://dx.doi.org/10.1017/s0022143000005505 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000005505 en eng Cambridge University Press (CUP) Journal of Glaciology volume 36, issue 122, page 17-30 ISSN 0022-1430 1727-5652 journal-article 1990 crcambridgeupr https://doi.org/10.1017/s0022143000005505 2024-06-26T04:04:31Z Abstract The surface and bottom topography of the central Greenland ice sheet was determined from airborne ice-radar soundings over a 180 km by 180 km grid centered on the 1974 “Summit” site (lat. 72°18′N., long. 37°55′W.), using the Technical University of Denmark 60 MHz ice radar. Over 6100 km of high-quality radar data were obtained, covering over 99'% of the grid, along lines spaced 12.5 km apart in both north-south and east-west directions. Aircraft location was done with an inertial navigation system (INS) and a pressure altimeter, with control provided by periodically flying over a known point at the center of the grid. The ice radar was used to determine ice thickness; the surface topography was determined independently using height-above-terrain measurements from the aircraft’s radar altimeter. The calculated surface topography is accurate to about ±6 m, with this error arising mostly from radar-altimeter errors. The ice thickness and bottom topography are accurate to about ±50 m, with this error dominated by the horizontal navigation uncertainties due to INS drift; this error increases to about ±125 m in areas of rough bottom relief (about 12% of the grid). The highest point on Greenland is at lat. 72°34′ N., long. 37°38′W., at an altitude of 3233 ± 6 m a.s.l. The ice surface at this point divides into three sectors, one facing north, one east-south-east, and one west-south-west, with each having a roughly uniform slope. The ice divide between the last two sectors is a well-defined ridge running almost due south. The ice is about 3025 m thick at the summit. Excluding the mountainous north-east corner of the grid, where the ice locally reaches a thickness of about 3470 m and the bed dips to about 370 m below sea-level, the maximum ice thickness, approximately 3375 m, occurs about 97 km south-south-west of the summit. The average bed altitude over the entire grid is 180 m and the average ice thickness is 2975 ± 235 m. The ice in most of the south-west quadrant of the grid is over 3200 m thick, and ... Article in Journal/Newspaper Greenland Ice Sheet Journal of Glaciology Cambridge University Press Journal of Glaciology 36 122 17 30 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
description |
Abstract The surface and bottom topography of the central Greenland ice sheet was determined from airborne ice-radar soundings over a 180 km by 180 km grid centered on the 1974 “Summit” site (lat. 72°18′N., long. 37°55′W.), using the Technical University of Denmark 60 MHz ice radar. Over 6100 km of high-quality radar data were obtained, covering over 99'% of the grid, along lines spaced 12.5 km apart in both north-south and east-west directions. Aircraft location was done with an inertial navigation system (INS) and a pressure altimeter, with control provided by periodically flying over a known point at the center of the grid. The ice radar was used to determine ice thickness; the surface topography was determined independently using height-above-terrain measurements from the aircraft’s radar altimeter. The calculated surface topography is accurate to about ±6 m, with this error arising mostly from radar-altimeter errors. The ice thickness and bottom topography are accurate to about ±50 m, with this error dominated by the horizontal navigation uncertainties due to INS drift; this error increases to about ±125 m in areas of rough bottom relief (about 12% of the grid). The highest point on Greenland is at lat. 72°34′ N., long. 37°38′W., at an altitude of 3233 ± 6 m a.s.l. The ice surface at this point divides into three sectors, one facing north, one east-south-east, and one west-south-west, with each having a roughly uniform slope. The ice divide between the last two sectors is a well-defined ridge running almost due south. The ice is about 3025 m thick at the summit. Excluding the mountainous north-east corner of the grid, where the ice locally reaches a thickness of about 3470 m and the bed dips to about 370 m below sea-level, the maximum ice thickness, approximately 3375 m, occurs about 97 km south-south-west of the summit. The average bed altitude over the entire grid is 180 m and the average ice thickness is 2975 ± 235 m. The ice in most of the south-west quadrant of the grid is over 3200 m thick, and ... |
format |
Article in Journal/Newspaper |
author |
Hodge, Steven M. Wright, David L. Bradley, Jerry A. Jacobel, Robert W. Skou, Neils Vaughn, Bruce |
spellingShingle |
Hodge, Steven M. Wright, David L. Bradley, Jerry A. Jacobel, Robert W. Skou, Neils Vaughn, Bruce Determination of the Surface and Bed Topography in Central Greenland |
author_facet |
Hodge, Steven M. Wright, David L. Bradley, Jerry A. Jacobel, Robert W. Skou, Neils Vaughn, Bruce |
author_sort |
Hodge, Steven M. |
title |
Determination of the Surface and Bed Topography in Central Greenland |
title_short |
Determination of the Surface and Bed Topography in Central Greenland |
title_full |
Determination of the Surface and Bed Topography in Central Greenland |
title_fullStr |
Determination of the Surface and Bed Topography in Central Greenland |
title_full_unstemmed |
Determination of the Surface and Bed Topography in Central Greenland |
title_sort |
determination of the surface and bed topography in central greenland |
publisher |
Cambridge University Press (CUP) |
publishDate |
1990 |
url |
http://dx.doi.org/10.1017/s0022143000005505 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000005505 |
genre |
Greenland Ice Sheet Journal of Glaciology |
genre_facet |
Greenland Ice Sheet Journal of Glaciology |
op_source |
Journal of Glaciology volume 36, issue 122, page 17-30 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000005505 |
container_title |
Journal of Glaciology |
container_volume |
36 |
container_issue |
122 |
container_start_page |
17 |
op_container_end_page |
30 |
_version_ |
1810447017780969472 |