Inverting ice surface elevation and velocity for bed topography and slipperiness beneath Thwaites Glacier
<p>There is significant uncertainty over how ice sheets and glaciers will respond to rising global temperatures. Limited knowledge of the topography and rheology of the ice–bed interface is a key cause of this uncertainty as models show that small changes in the bed can have a large influence...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2022-09-01
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| Series: | The Cryosphere |
| Online Access: | https://tc.copernicus.org/articles/16/3867/2022/tc-16-3867-2022.pdf |
| _version_ | 1811208369691688960 |
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| author | H. Ockenden R. G. Bingham A. Curtis D. Goldberg |
| author_facet | H. Ockenden R. G. Bingham A. Curtis D. Goldberg |
| author_sort | H. Ockenden |
| collection | DOAJ |
| description | <p>There is significant uncertainty over how ice sheets and glaciers will respond to rising global temperatures. Limited knowledge of the topography
and rheology of the ice–bed interface is a key cause of this uncertainty as models show that small changes in the bed can have a large influence on
predicted rates of ice loss. Most of our detailed knowledge of bed topography comes from airborne and ground-penetrating radar
observations. However, these direct observations are not spaced closely enough to meet the requirements of ice-sheet models, so interpolation and
inversion methods are used to fill in the gaps. Here we present the results of a new inversion of surface elevation and velocity data over Thwaites
Glacier, West Antarctica, for bed topography and slipperiness (i.e. the degree of basal slip for a given level of drag). The inversion is based on a
steady-state linear perturbation analysis of the shallow-ice-stream equations. The method works by identifying disturbances to surface flow which
are caused by obstacles or sticky patches in the bed and can therefore be applied wherever the shallow-ice-stream equations hold and where surface
data are available, even where the ice thickness is not well known. We assess the performance of the inversion for topography with the available
radar data. Although the topographic output from the inversion is less successful where the bed slopes steeply, it compares well with radar data
from the central trunk of the glacier for medium-wavelength features (5–50 <span class="inline-formula">km</span>). This method could therefore be useful as an
independent test of other interpolation methods such as mass conservation and kriging. We do not have data to allow us to assess the success of the
slipperiness results from our inversions, but we provide maps that may guide future seismic data collection across Thwaites Glacier. The methods
presented here show significant promise for using high-resolution satellite datasets, calibrated by sparser field datasets, to generate high-resolution bed topography products across the ice sheets and therefore contribute to reduced uncertainty in predictions of future sea-level rise.</p> |
| first_indexed | 2024-04-12T04:20:00Z |
| format | Article |
| id | doaj.art-6c4a8daecebf421e9989be709f1e133d |
| institution | Directory Open Access Journal |
| issn | 1994-0416 1994-0424 |
| language | English |
| last_indexed | 2024-04-12T04:20:00Z |
| publishDate | 2022-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The Cryosphere |
| spelling | doaj.art-6c4a8daecebf421e9989be709f1e133d2022-12-22T03:48:16ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242022-09-01163867388710.5194/tc-16-3867-2022Inverting ice surface elevation and velocity for bed topography and slipperiness beneath Thwaites GlacierH. OckendenR. G. BinghamA. CurtisD. Goldberg<p>There is significant uncertainty over how ice sheets and glaciers will respond to rising global temperatures. Limited knowledge of the topography and rheology of the ice–bed interface is a key cause of this uncertainty as models show that small changes in the bed can have a large influence on predicted rates of ice loss. Most of our detailed knowledge of bed topography comes from airborne and ground-penetrating radar observations. However, these direct observations are not spaced closely enough to meet the requirements of ice-sheet models, so interpolation and inversion methods are used to fill in the gaps. Here we present the results of a new inversion of surface elevation and velocity data over Thwaites Glacier, West Antarctica, for bed topography and slipperiness (i.e. the degree of basal slip for a given level of drag). The inversion is based on a steady-state linear perturbation analysis of the shallow-ice-stream equations. The method works by identifying disturbances to surface flow which are caused by obstacles or sticky patches in the bed and can therefore be applied wherever the shallow-ice-stream equations hold and where surface data are available, even where the ice thickness is not well known. We assess the performance of the inversion for topography with the available radar data. Although the topographic output from the inversion is less successful where the bed slopes steeply, it compares well with radar data from the central trunk of the glacier for medium-wavelength features (5–50 <span class="inline-formula">km</span>). This method could therefore be useful as an independent test of other interpolation methods such as mass conservation and kriging. We do not have data to allow us to assess the success of the slipperiness results from our inversions, but we provide maps that may guide future seismic data collection across Thwaites Glacier. The methods presented here show significant promise for using high-resolution satellite datasets, calibrated by sparser field datasets, to generate high-resolution bed topography products across the ice sheets and therefore contribute to reduced uncertainty in predictions of future sea-level rise.</p>https://tc.copernicus.org/articles/16/3867/2022/tc-16-3867-2022.pdf |
| spellingShingle | H. Ockenden R. G. Bingham A. Curtis D. Goldberg Inverting ice surface elevation and velocity for bed topography and slipperiness beneath Thwaites Glacier The Cryosphere |
| title | Inverting ice surface elevation and velocity for bed topography and slipperiness beneath Thwaites Glacier |
| title_full | Inverting ice surface elevation and velocity for bed topography and slipperiness beneath Thwaites Glacier |
| title_fullStr | Inverting ice surface elevation and velocity for bed topography and slipperiness beneath Thwaites Glacier |
| title_full_unstemmed | Inverting ice surface elevation and velocity for bed topography and slipperiness beneath Thwaites Glacier |
| title_short | Inverting ice surface elevation and velocity for bed topography and slipperiness beneath Thwaites Glacier |
| title_sort | inverting ice surface elevation and velocity for bed topography and slipperiness beneath thwaites glacier |
| url | https://tc.copernicus.org/articles/16/3867/2022/tc-16-3867-2022.pdf |
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