Flow speed within the Antarctic ice sheet and its controls inferred from satellite observations
Accurate dynamical models of the Antarctic ice sheet with carefully specified initial conditions and well-calibrated rheological parameters are needed to forecast global sea level. By adapting an inverse method previously used in electric impedance tomography, we infer present-day flow speeds within...
Published in: | Journal of Geophysical Research: Earth Surface |
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American Geophysical Union
2015
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ftnerc:oai:nora.nerc.ac.uk:505960 2023-05-15T13:48:08+02:00 Flow speed within the Antarctic ice sheet and its controls inferred from satellite observations Arthern, Robert J. Hindmarsh, Richard C.A. Williams, C. Rosie 2015-07 text http://nora.nerc.ac.uk/id/eprint/505960/ https://nora.nerc.ac.uk/id/eprint/505960/1/Arthern_et_al-2015-Journal_of_Geophysical_Research__Earth_Surface.pdf https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014JF003239 en eng American Geophysical Union https://nora.nerc.ac.uk/id/eprint/505960/1/Arthern_et_al-2015-Journal_of_Geophysical_Research__Earth_Surface.pdf Arthern, Robert J. orcid:0000-0002-3762-8219 Hindmarsh, Richard C.A. orcid:0000-0003-1633-2416 Williams, C. Rosie. 2015 Flow speed within the Antarctic ice sheet and its controls inferred from satellite observations. Journal of Geophysical Research: Earth Surface, 120 (7). 1171-1188. https://doi.org/10.1002/2014JF003239 <https://doi.org/10.1002/2014JF003239> Publication - Article PeerReviewed 2015 ftnerc https://doi.org/10.1002/2014JF003239 2023-02-04T19:39:06Z Accurate dynamical models of the Antarctic ice sheet with carefully specified initial conditions and well-calibrated rheological parameters are needed to forecast global sea level. By adapting an inverse method previously used in electric impedance tomography, we infer present-day flow speeds within the ice sheet. This inversion uses satellite observations of surface velocity, snow accumulation rate, and rate of change of surface elevation to estimate the basal drag coefficient and an ice stiffness parameter that influences viscosity. We represent interior ice motion using a vertically integrated approximation to incompressible Stokes flow. This model represents vertical shearing within the ice and membrane stresses caused by horizontal stretching and shearing. Combining observations and model, we recover marked geographical variations in the basal drag coefficient. Relative changes in basal shear stress are smaller. No simple sliding law adequately represents basal shear stress as a function of sliding speed. Low basal shear stress predominates in central East Antarctica, where thick insulating ice allows liquid water at the base to lubricate sliding. Higher shear stress occurs in coastal East Antarctica, where a frozen bed is more likely. Examining Thwaites glacier in more detail shows that the slowest sliding often coincides with elevated basal topography. Differences between our results and a similar adjoint-based inversion suggest that inversion or regularization methods can influence recovered parameters for slow sliding and finer scales; on broader scales we recover a similar pattern of low basal drag underneath major ice streams and extensive regions in East Antarctica that move by basal sliding. Article in Journal/Newspaper Antarc* Antarctic Antarctica East Antarctica Ice Sheet Thwaites Glacier Natural Environment Research Council: NERC Open Research Archive Antarctic The Antarctic East Antarctica Thwaites Glacier ENVELOPE(-106.750,-106.750,-75.500,-75.500) Journal of Geophysical Research: Earth Surface 120 7 1171 1188 |
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Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
English |
description |
Accurate dynamical models of the Antarctic ice sheet with carefully specified initial conditions and well-calibrated rheological parameters are needed to forecast global sea level. By adapting an inverse method previously used in electric impedance tomography, we infer present-day flow speeds within the ice sheet. This inversion uses satellite observations of surface velocity, snow accumulation rate, and rate of change of surface elevation to estimate the basal drag coefficient and an ice stiffness parameter that influences viscosity. We represent interior ice motion using a vertically integrated approximation to incompressible Stokes flow. This model represents vertical shearing within the ice and membrane stresses caused by horizontal stretching and shearing. Combining observations and model, we recover marked geographical variations in the basal drag coefficient. Relative changes in basal shear stress are smaller. No simple sliding law adequately represents basal shear stress as a function of sliding speed. Low basal shear stress predominates in central East Antarctica, where thick insulating ice allows liquid water at the base to lubricate sliding. Higher shear stress occurs in coastal East Antarctica, where a frozen bed is more likely. Examining Thwaites glacier in more detail shows that the slowest sliding often coincides with elevated basal topography. Differences between our results and a similar adjoint-based inversion suggest that inversion or regularization methods can influence recovered parameters for slow sliding and finer scales; on broader scales we recover a similar pattern of low basal drag underneath major ice streams and extensive regions in East Antarctica that move by basal sliding. |
format |
Article in Journal/Newspaper |
author |
Arthern, Robert J. Hindmarsh, Richard C.A. Williams, C. Rosie |
spellingShingle |
Arthern, Robert J. Hindmarsh, Richard C.A. Williams, C. Rosie Flow speed within the Antarctic ice sheet and its controls inferred from satellite observations |
author_facet |
Arthern, Robert J. Hindmarsh, Richard C.A. Williams, C. Rosie |
author_sort |
Arthern, Robert J. |
title |
Flow speed within the Antarctic ice sheet and its controls inferred from satellite observations |
title_short |
Flow speed within the Antarctic ice sheet and its controls inferred from satellite observations |
title_full |
Flow speed within the Antarctic ice sheet and its controls inferred from satellite observations |
title_fullStr |
Flow speed within the Antarctic ice sheet and its controls inferred from satellite observations |
title_full_unstemmed |
Flow speed within the Antarctic ice sheet and its controls inferred from satellite observations |
title_sort |
flow speed within the antarctic ice sheet and its controls inferred from satellite observations |
publisher |
American Geophysical Union |
publishDate |
2015 |
url |
http://nora.nerc.ac.uk/id/eprint/505960/ https://nora.nerc.ac.uk/id/eprint/505960/1/Arthern_et_al-2015-Journal_of_Geophysical_Research__Earth_Surface.pdf https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014JF003239 |
long_lat |
ENVELOPE(-106.750,-106.750,-75.500,-75.500) |
geographic |
Antarctic The Antarctic East Antarctica Thwaites Glacier |
geographic_facet |
Antarctic The Antarctic East Antarctica Thwaites Glacier |
genre |
Antarc* Antarctic Antarctica East Antarctica Ice Sheet Thwaites Glacier |
genre_facet |
Antarc* Antarctic Antarctica East Antarctica Ice Sheet Thwaites Glacier |
op_relation |
https://nora.nerc.ac.uk/id/eprint/505960/1/Arthern_et_al-2015-Journal_of_Geophysical_Research__Earth_Surface.pdf Arthern, Robert J. orcid:0000-0002-3762-8219 Hindmarsh, Richard C.A. orcid:0000-0003-1633-2416 Williams, C. Rosie. 2015 Flow speed within the Antarctic ice sheet and its controls inferred from satellite observations. Journal of Geophysical Research: Earth Surface, 120 (7). 1171-1188. https://doi.org/10.1002/2014JF003239 <https://doi.org/10.1002/2014JF003239> |
op_doi |
https://doi.org/10.1002/2014JF003239 |
container_title |
Journal of Geophysical Research: Earth Surface |
container_volume |
120 |
container_issue |
7 |
container_start_page |
1171 |
op_container_end_page |
1188 |
_version_ |
1766248749383811072 |