Self-affine subglacial roughness: consequences for radar scattering and basal water discrimination in northern Greenland
Subglacial roughness can be determined at a variety of length scales from radio-echo sounding (RES) data either via statistical analysis of topography or inferred from basal radar scattering. Past studies have demonstrated that subglacial terrain exhibits self-affine (power law) roughness scaling be...
Published in: | The Cryosphere |
---|---|
Main Authors: | , , , , , , |
Format: | Text |
Language: | English |
Published: |
2018
|
Subjects: | |
Online Access: | https://doi.org/10.5194/tc-11-1247-2017 https://tc.copernicus.org/articles/11/1247/2017/ |
id |
ftcopernicus:oai:publications.copernicus.org:tc56302 |
---|---|
record_format |
openpolar |
spelling |
ftcopernicus:oai:publications.copernicus.org:tc56302 2023-05-15T16:27:59+02:00 Self-affine subglacial roughness: consequences for radar scattering and basal water discrimination in northern Greenland Jordan, Thomas M. Cooper, Michael A. Schroeder, Dustin M. Williams, Christopher N. Paden, John D. Siegert, Martin J. Bamber, Jonathan L. 2018-09-27 application/pdf https://doi.org/10.5194/tc-11-1247-2017 https://tc.copernicus.org/articles/11/1247/2017/ eng eng doi:10.5194/tc-11-1247-2017 https://tc.copernicus.org/articles/11/1247/2017/ eISSN: 1994-0424 Text 2018 ftcopernicus https://doi.org/10.5194/tc-11-1247-2017 2020-07-20T16:23:44Z Subglacial roughness can be determined at a variety of length scales from radio-echo sounding (RES) data either via statistical analysis of topography or inferred from basal radar scattering. Past studies have demonstrated that subglacial terrain exhibits self-affine (power law) roughness scaling behaviour, but existing radar scattering models do not take this into account. Here, using RES data from northern Greenland, we introduce a self-affine statistical framework that enables a consistent integration of topographic-scale roughness with the electromagnetic theory of radar scattering. We demonstrate that the degree of radar scattering, quantified using the waveform abruptness (pulse peakiness), is topographically controlled by the Hurst (roughness power law) exponent. Notably, specular bed reflections are associated with a lower Hurst exponent, with diffuse scattering associated with a higher Hurst exponent. Abrupt waveforms (specular reflections) have previously been used as a RES diagnostic for basal water, and to test this assumption we compare our radar scattering map with a recent prediction for the basal thermal state. We demonstrate that the majority of thawed regions (above pressure melting point) exhibit a diffuse scattering signature, which is in contradiction to the prior approach. Self-affine statistics provide a generalised model for subglacial terrain and can improve our understanding of the relationship between basal properties and ice-sheet dynamics. Text Greenland Ice Sheet Copernicus Publications: E-Journals Greenland The Cryosphere 11 3 1247 1264 |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
Subglacial roughness can be determined at a variety of length scales from radio-echo sounding (RES) data either via statistical analysis of topography or inferred from basal radar scattering. Past studies have demonstrated that subglacial terrain exhibits self-affine (power law) roughness scaling behaviour, but existing radar scattering models do not take this into account. Here, using RES data from northern Greenland, we introduce a self-affine statistical framework that enables a consistent integration of topographic-scale roughness with the electromagnetic theory of radar scattering. We demonstrate that the degree of radar scattering, quantified using the waveform abruptness (pulse peakiness), is topographically controlled by the Hurst (roughness power law) exponent. Notably, specular bed reflections are associated with a lower Hurst exponent, with diffuse scattering associated with a higher Hurst exponent. Abrupt waveforms (specular reflections) have previously been used as a RES diagnostic for basal water, and to test this assumption we compare our radar scattering map with a recent prediction for the basal thermal state. We demonstrate that the majority of thawed regions (above pressure melting point) exhibit a diffuse scattering signature, which is in contradiction to the prior approach. Self-affine statistics provide a generalised model for subglacial terrain and can improve our understanding of the relationship between basal properties and ice-sheet dynamics. |
format |
Text |
author |
Jordan, Thomas M. Cooper, Michael A. Schroeder, Dustin M. Williams, Christopher N. Paden, John D. Siegert, Martin J. Bamber, Jonathan L. |
spellingShingle |
Jordan, Thomas M. Cooper, Michael A. Schroeder, Dustin M. Williams, Christopher N. Paden, John D. Siegert, Martin J. Bamber, Jonathan L. Self-affine subglacial roughness: consequences for radar scattering and basal water discrimination in northern Greenland |
author_facet |
Jordan, Thomas M. Cooper, Michael A. Schroeder, Dustin M. Williams, Christopher N. Paden, John D. Siegert, Martin J. Bamber, Jonathan L. |
author_sort |
Jordan, Thomas M. |
title |
Self-affine subglacial roughness: consequences for radar scattering and basal water discrimination in northern Greenland |
title_short |
Self-affine subglacial roughness: consequences for radar scattering and basal water discrimination in northern Greenland |
title_full |
Self-affine subglacial roughness: consequences for radar scattering and basal water discrimination in northern Greenland |
title_fullStr |
Self-affine subglacial roughness: consequences for radar scattering and basal water discrimination in northern Greenland |
title_full_unstemmed |
Self-affine subglacial roughness: consequences for radar scattering and basal water discrimination in northern Greenland |
title_sort |
self-affine subglacial roughness: consequences for radar scattering and basal water discrimination in northern greenland |
publishDate |
2018 |
url |
https://doi.org/10.5194/tc-11-1247-2017 https://tc.copernicus.org/articles/11/1247/2017/ |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Ice Sheet |
genre_facet |
Greenland Ice Sheet |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-11-1247-2017 https://tc.copernicus.org/articles/11/1247/2017/ |
op_doi |
https://doi.org/10.5194/tc-11-1247-2017 |
container_title |
The Cryosphere |
container_volume |
11 |
container_issue |
3 |
container_start_page |
1247 |
op_container_end_page |
1264 |
_version_ |
1766017601851359232 |