Inverting for Antarctic subglacial topography using variability in satellite remote-sensing observations of the ice surface
As global temperatures rise, melting of the Antarctic Ice Sheet will lead to increasing global sea levels, but we do not currently have good constraints on the speed of future sea-level rise. A lack of knowledge about the subglacial topography of the ice sheets is a key cause of this uncertainty, as...
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The University of Edinburgh
2024
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Online Access: | https://hdl.handle.net/1842/41877 https://doi.org/10.7488/era/4600 |
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ftunivedinburgh:oai:era.ed.ac.uk:1842/41877 2024-09-09T19:10:19+00:00 Inverting for Antarctic subglacial topography using variability in satellite remote-sensing observations of the ice surface Ockenden, Helen Bingham, Robert Curtis, Andrew Goldberg, Daniel Giannopoulos, Antonios Bollasina, Massimo Natural Environment Research Council (NERC) 2024-06-12 application/pdf https://hdl.handle.net/1842/41877 https://doi.org/10.7488/era/4600 en eng The University of Edinburgh Ockenden, H., Bingham, R. G., Curtis, A., and Goldberg, D. (2022). Inverting ice-surface elevation and velocity for bed topography and slipperiness beneath Thwaites Glacier. The Cryosphere, 16(9):3867–3887. Ockenden, H., Bingham, R. G., Curtis, A., and Goldberg, D. (2023). Ice-Flow Perturbation Analysis: a method to estimate ice-sheet bed topography and conditions from surface datasets. Journal of Glaciology, pages 1–10 https://hdl.handle.net/1842/41877 http://dx.doi.org/10.7488/era/4600 2025-06-12 subglacial topography Antarctic ice sheets ice-bed interface Ice Flow Perturbation Analysis Thwaites Glacier ice-penetrating radar survey Pine Island Glacier mapping Thesis or Dissertation Doctoral PhD Doctor of Philosophy 2024 ftunivedinburgh https://doi.org/10.7488/era/4600 2024-06-19T00:04:01Z As global temperatures rise, melting of the Antarctic Ice Sheet will lead to increasing global sea levels, but we do not currently have good constraints on the speed of future sea-level rise. A lack of knowledge about the subglacial topography of the ice sheets is a key cause of this uncertainty, as small variations in subglacial topography can have a significant influence on the rates of ice loss in numerical ice-sheet models. Our current understanding of subglacial topography comes from airborne and ground-based geophysical observations, which are expensive and time consuming to collect, and there are very few regions where the 1-2 km resolution required by ice-sheet models is achieved. When interpolation methods such as kriging, mass conservation and flow-line diffusion are applied to fill the gaps, they can miss influential mesoscale (2-30 km) subglacial features. In this thesis, I use a mathematical description of the relationship between surface and subglacial topography in flowing ice, alongside high-resolution observations of ice surface topography and velocities to invert for Antarctic subglacial topography and slipperiness. I develop a method for doing this which I term Ice Flow Perturbation Analysis (IFPA). Initially, I use synthetic models of subglacial topography to explore the range of landforms which can be resolved with this approach. I apply the IFPA method to Thwaites Glacier in West Antarctica in order to compare the results with high-resolution ice-penetrating radar measurements, and to select appropriate parameter values. I also apply the IFPA method to Pine Island Glacier in West Antarctica, and show that IFPA can resolve landforms which are not present in topographic maps which have interpolated between geophysical survey lines using flow-line diffusion. Finally, I use an updated version of the IFPA methodology to look at subglacial topography across the entire Antarctic continent. The new topography map reveals new features at the bed, and fills in the details for partially-surveyed ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Antarctica Ice Sheet Journal of Glaciology Pine Island Pine Island Glacier The Cryosphere Thwaites Glacier West Antarctica Edinburgh Research Archive (ERA - University of Edinburgh) Antarctic The Antarctic West Antarctica Pine Island Glacier ENVELOPE(-101.000,-101.000,-75.000,-75.000) Thwaites Glacier ENVELOPE(-106.750,-106.750,-75.500,-75.500) |
institution |
Open Polar |
collection |
Edinburgh Research Archive (ERA - University of Edinburgh) |
op_collection_id |
ftunivedinburgh |
language |
English |
topic |
subglacial topography Antarctic ice sheets ice-bed interface Ice Flow Perturbation Analysis Thwaites Glacier ice-penetrating radar survey Pine Island Glacier mapping |
spellingShingle |
subglacial topography Antarctic ice sheets ice-bed interface Ice Flow Perturbation Analysis Thwaites Glacier ice-penetrating radar survey Pine Island Glacier mapping Ockenden, Helen Inverting for Antarctic subglacial topography using variability in satellite remote-sensing observations of the ice surface |
topic_facet |
subglacial topography Antarctic ice sheets ice-bed interface Ice Flow Perturbation Analysis Thwaites Glacier ice-penetrating radar survey Pine Island Glacier mapping |
description |
As global temperatures rise, melting of the Antarctic Ice Sheet will lead to increasing global sea levels, but we do not currently have good constraints on the speed of future sea-level rise. A lack of knowledge about the subglacial topography of the ice sheets is a key cause of this uncertainty, as small variations in subglacial topography can have a significant influence on the rates of ice loss in numerical ice-sheet models. Our current understanding of subglacial topography comes from airborne and ground-based geophysical observations, which are expensive and time consuming to collect, and there are very few regions where the 1-2 km resolution required by ice-sheet models is achieved. When interpolation methods such as kriging, mass conservation and flow-line diffusion are applied to fill the gaps, they can miss influential mesoscale (2-30 km) subglacial features. In this thesis, I use a mathematical description of the relationship between surface and subglacial topography in flowing ice, alongside high-resolution observations of ice surface topography and velocities to invert for Antarctic subglacial topography and slipperiness. I develop a method for doing this which I term Ice Flow Perturbation Analysis (IFPA). Initially, I use synthetic models of subglacial topography to explore the range of landforms which can be resolved with this approach. I apply the IFPA method to Thwaites Glacier in West Antarctica in order to compare the results with high-resolution ice-penetrating radar measurements, and to select appropriate parameter values. I also apply the IFPA method to Pine Island Glacier in West Antarctica, and show that IFPA can resolve landforms which are not present in topographic maps which have interpolated between geophysical survey lines using flow-line diffusion. Finally, I use an updated version of the IFPA methodology to look at subglacial topography across the entire Antarctic continent. The new topography map reveals new features at the bed, and fills in the details for partially-surveyed ... |
author2 |
Bingham, Robert Curtis, Andrew Goldberg, Daniel Giannopoulos, Antonios Bollasina, Massimo Natural Environment Research Council (NERC) |
format |
Doctoral or Postdoctoral Thesis |
author |
Ockenden, Helen |
author_facet |
Ockenden, Helen |
author_sort |
Ockenden, Helen |
title |
Inverting for Antarctic subglacial topography using variability in satellite remote-sensing observations of the ice surface |
title_short |
Inverting for Antarctic subglacial topography using variability in satellite remote-sensing observations of the ice surface |
title_full |
Inverting for Antarctic subglacial topography using variability in satellite remote-sensing observations of the ice surface |
title_fullStr |
Inverting for Antarctic subglacial topography using variability in satellite remote-sensing observations of the ice surface |
title_full_unstemmed |
Inverting for Antarctic subglacial topography using variability in satellite remote-sensing observations of the ice surface |
title_sort |
inverting for antarctic subglacial topography using variability in satellite remote-sensing observations of the ice surface |
publisher |
The University of Edinburgh |
publishDate |
2024 |
url |
https://hdl.handle.net/1842/41877 https://doi.org/10.7488/era/4600 |
long_lat |
ENVELOPE(-101.000,-101.000,-75.000,-75.000) ENVELOPE(-106.750,-106.750,-75.500,-75.500) |
geographic |
Antarctic The Antarctic West Antarctica Pine Island Glacier Thwaites Glacier |
geographic_facet |
Antarctic The Antarctic West Antarctica Pine Island Glacier Thwaites Glacier |
genre |
Antarc* Antarctic Antarctica Ice Sheet Journal of Glaciology Pine Island Pine Island Glacier The Cryosphere Thwaites Glacier West Antarctica |
genre_facet |
Antarc* Antarctic Antarctica Ice Sheet Journal of Glaciology Pine Island Pine Island Glacier The Cryosphere Thwaites Glacier West Antarctica |
op_relation |
Ockenden, H., Bingham, R. G., Curtis, A., and Goldberg, D. (2022). Inverting ice-surface elevation and velocity for bed topography and slipperiness beneath Thwaites Glacier. The Cryosphere, 16(9):3867–3887. Ockenden, H., Bingham, R. G., Curtis, A., and Goldberg, D. (2023). Ice-Flow Perturbation Analysis: a method to estimate ice-sheet bed topography and conditions from surface datasets. Journal of Glaciology, pages 1–10 https://hdl.handle.net/1842/41877 http://dx.doi.org/10.7488/era/4600 |
op_rights |
2025-06-12 |
op_doi |
https://doi.org/10.7488/era/4600 |
_version_ |
1809825137248174080 |