Getting around Antarctica: New High-Resolution Mappings of the Grounded and Freely-Floating Boundaries of the Antarctic Ice Sheet Created for the International Polar Year
Two ice-dynamic transitions of the Antarctic ice sheet - the boundary of grounded ice features and the freely-floating boundary - are mapped at 15-m resolution by participants of the International Polar Year project ASAID using customized software combining Landsat-7 imagery and ICESat/GLAS laser al...
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ftnasantrs:oai:casi.ntrs.nasa.gov:20120010397 2023-05-15T13:33:56+02:00 Getting around Antarctica: New High-Resolution Mappings of the Grounded and Freely-Floating Boundaries of the Antarctic Ice Sheet Created for the International Polar Year Rack, W. Urbini, S. Drews, R. Vornberger, P. Bohlander, J. Padman, L. Brunt, K. Young, N. Choi, H. Hall, M. Bindschadler, R. Corr, H. Fricker, H. Rotschkly, G. Bingham, R. Hindmarsh, R. Kohler, J. Wichlacz, A. Unclassified, Unlimited, Publicly available July 18, 2011 application/pdf http://hdl.handle.net/2060/20120010397 unknown Document ID: 20120010397 http://hdl.handle.net/2060/20120010397 Copyright, Distribution as joint owner in the copyright CASI Geosciences (General) GSFC.JA.00325.2012 The Cryosphere; 5; 569-588 2011 ftnasantrs 2019-07-21T00:49:55Z Two ice-dynamic transitions of the Antarctic ice sheet - the boundary of grounded ice features and the freely-floating boundary - are mapped at 15-m resolution by participants of the International Polar Year project ASAID using customized software combining Landsat-7 imagery and ICESat/GLAS laser altimetry. The grounded ice boundary is 53 610 km long; 74% abuts to floating ice shelves or outlet glaciers, 19% is adjacent to open or sea-ice covered ocean, and 7% of the boundary ice terminates on land. The freely-floating boundary, called here the hydrostatic line, is the most landward position on ice shelves that expresses the full amplitude of oscillating ocean tides. It extends 27 521 km and is discontinuous. Positional (one-sigma) accuracies of the grounded ice boundary vary an order of magnitude ranging from +/- 52m for the land and open-ocean terminating segments to +/- 502m for the outlet glaciers. The hydrostatic line is less well positioned with errors over 2 km. Elevations along each line are selected from 6 candidate digital elevation models based on their agreement with ICESat elevation values and surface shape inferred from the Landsat imagery. Elevations along the hydrostatic line are converted to ice thicknesses by applying a firn-correction factor and a flotation criterion. BEDMAP-compiled data and other airborne data are compared to the ASAID elevations and ice thicknesses to arrive at quantitative (one-sigma) uncertainties of surface elevations of +/-3.6, +/-9.6, +/-11.4, +/-30 and +/-100m for five ASAID-assigned confidence levels. Over one-half of the surface elevations along the grounded ice boundary and over one-third of the hydrostatic line elevations are ranked in the highest two confidence categories. A comparison between ASAID-calculated ice shelf thicknesses and BEDMAP-compiled data indicate a thin-ice bias of 41.2+/-71.3m for the ASAID ice thicknesses. The relationship between the seaward offset of the hydrostatic line from the grounded ice boundary only weakly matches a prediction based on beam theory. The mapped products along with the customized software to generate them and a variety of intermediate products are available from the National Snow and Ice Data Center. Other/Unknown Material Antarc* Antarctic Antarctica Ice Sheet Ice Shelf Ice Shelves International Polar Year National Snow and Ice Data Center Sea ice NASA Technical Reports Server (NTRS) Antarctic The Antarctic |
institution |
Open Polar |
collection |
NASA Technical Reports Server (NTRS) |
op_collection_id |
ftnasantrs |
language |
unknown |
topic |
Geosciences (General) |
spellingShingle |
Geosciences (General) Rack, W. Urbini, S. Drews, R. Vornberger, P. Bohlander, J. Padman, L. Brunt, K. Young, N. Choi, H. Hall, M. Bindschadler, R. Corr, H. Fricker, H. Rotschkly, G. Bingham, R. Hindmarsh, R. Kohler, J. Wichlacz, A. Getting around Antarctica: New High-Resolution Mappings of the Grounded and Freely-Floating Boundaries of the Antarctic Ice Sheet Created for the International Polar Year |
topic_facet |
Geosciences (General) |
description |
Two ice-dynamic transitions of the Antarctic ice sheet - the boundary of grounded ice features and the freely-floating boundary - are mapped at 15-m resolution by participants of the International Polar Year project ASAID using customized software combining Landsat-7 imagery and ICESat/GLAS laser altimetry. The grounded ice boundary is 53 610 km long; 74% abuts to floating ice shelves or outlet glaciers, 19% is adjacent to open or sea-ice covered ocean, and 7% of the boundary ice terminates on land. The freely-floating boundary, called here the hydrostatic line, is the most landward position on ice shelves that expresses the full amplitude of oscillating ocean tides. It extends 27 521 km and is discontinuous. Positional (one-sigma) accuracies of the grounded ice boundary vary an order of magnitude ranging from +/- 52m for the land and open-ocean terminating segments to +/- 502m for the outlet glaciers. The hydrostatic line is less well positioned with errors over 2 km. Elevations along each line are selected from 6 candidate digital elevation models based on their agreement with ICESat elevation values and surface shape inferred from the Landsat imagery. Elevations along the hydrostatic line are converted to ice thicknesses by applying a firn-correction factor and a flotation criterion. BEDMAP-compiled data and other airborne data are compared to the ASAID elevations and ice thicknesses to arrive at quantitative (one-sigma) uncertainties of surface elevations of +/-3.6, +/-9.6, +/-11.4, +/-30 and +/-100m for five ASAID-assigned confidence levels. Over one-half of the surface elevations along the grounded ice boundary and over one-third of the hydrostatic line elevations are ranked in the highest two confidence categories. A comparison between ASAID-calculated ice shelf thicknesses and BEDMAP-compiled data indicate a thin-ice bias of 41.2+/-71.3m for the ASAID ice thicknesses. The relationship between the seaward offset of the hydrostatic line from the grounded ice boundary only weakly matches a prediction based on beam theory. The mapped products along with the customized software to generate them and a variety of intermediate products are available from the National Snow and Ice Data Center. |
format |
Other/Unknown Material |
author |
Rack, W. Urbini, S. Drews, R. Vornberger, P. Bohlander, J. Padman, L. Brunt, K. Young, N. Choi, H. Hall, M. Bindschadler, R. Corr, H. Fricker, H. Rotschkly, G. Bingham, R. Hindmarsh, R. Kohler, J. Wichlacz, A. |
author_facet |
Rack, W. Urbini, S. Drews, R. Vornberger, P. Bohlander, J. Padman, L. Brunt, K. Young, N. Choi, H. Hall, M. Bindschadler, R. Corr, H. Fricker, H. Rotschkly, G. Bingham, R. Hindmarsh, R. Kohler, J. Wichlacz, A. |
author_sort |
Rack, W. |
title |
Getting around Antarctica: New High-Resolution Mappings of the Grounded and Freely-Floating Boundaries of the Antarctic Ice Sheet Created for the International Polar Year |
title_short |
Getting around Antarctica: New High-Resolution Mappings of the Grounded and Freely-Floating Boundaries of the Antarctic Ice Sheet Created for the International Polar Year |
title_full |
Getting around Antarctica: New High-Resolution Mappings of the Grounded and Freely-Floating Boundaries of the Antarctic Ice Sheet Created for the International Polar Year |
title_fullStr |
Getting around Antarctica: New High-Resolution Mappings of the Grounded and Freely-Floating Boundaries of the Antarctic Ice Sheet Created for the International Polar Year |
title_full_unstemmed |
Getting around Antarctica: New High-Resolution Mappings of the Grounded and Freely-Floating Boundaries of the Antarctic Ice Sheet Created for the International Polar Year |
title_sort |
getting around antarctica: new high-resolution mappings of the grounded and freely-floating boundaries of the antarctic ice sheet created for the international polar year |
publishDate |
2011 |
url |
http://hdl.handle.net/2060/20120010397 |
op_coverage |
Unclassified, Unlimited, Publicly available |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic Antarctica Ice Sheet Ice Shelf Ice Shelves International Polar Year National Snow and Ice Data Center Sea ice |
genre_facet |
Antarc* Antarctic Antarctica Ice Sheet Ice Shelf Ice Shelves International Polar Year National Snow and Ice Data Center Sea ice |
op_source |
CASI |
op_relation |
Document ID: 20120010397 http://hdl.handle.net/2060/20120010397 |
op_rights |
Copyright, Distribution as joint owner in the copyright |
_version_ |
1766047312723836928 |