 |
| Titel |
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 |
| VerfasserIn |
R. Bindschadler, H. Choi, A. Wichlacz, R. Bingham, J. Bohlander, K. Brunt, H. Corr, R. Drews, H. Fricker, M. Hall, R. Hindmarsh, J. Köhler, L. Padman, W. Rack, G. Rotschky, S. Urbini, P. Vornberger, N. Young |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1994-0416
|
| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 5, no. 3 ; Nr. 5, no. 3 (2011-07-18), S.569-588 |
| Datensatznummer |
250002590
|
| Publikation (Nr.) |
 copernicus.org/tc-5-569-2011.pdf |
|
|
|
|
|
| Zusammenfassung |
| 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 ±52 m for the land and open-ocean
terminating segments to ±502 m 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 ±100 m 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 ± 71.3 m 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. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|