An ice sheet wide framework for radar-inference of englacial attenuation and basal reflection with application to Greenland
Radar inference of the bulk properties of glacier beds, most notably identifying basal melting, is, in general, derived from the basal reflection coefficient. On the scale of an ice sheet, unambiguous determination of basal reflection is primarily limited by uncertainty in the englacial attenuation...
Published in: | The Cryosphere |
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European Geosciences Union (EGU)
2016
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Online Access: | http://hdl.handle.net/10044/1/37416 https://doi.org/10.5194/tc-10-1547-2016 |
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ftimperialcol:oai:spiral.imperial.ac.uk:10044/1/37416 2023-05-15T16:03:05+02:00 An ice sheet wide framework for radar-inference of englacial attenuation and basal reflection with application to Greenland Jordan, T Bamber, J Williams, C Paden, J Siegert, MJ Huybrechts, P Gagliardini, O Gillet-Chaulet, F Natural Environment Research Council (NERC) Natural Environment Research Council (NERC) 2016-06-24 http://hdl.handle.net/10044/1/37416 https://doi.org/10.5194/tc-10-1547-2016 unknown European Geosciences Union (EGU) Cryosphere © Author(s) 2016. CC Attribution 3.0 License. CC-BY 1570 1547 Meteorology & Atmospheric Sciences 0405 Oceanography 0406 Physical Geography And Environmental Geoscience Journal Article 2016 ftimperialcol https://doi.org/10.5194/tc-10-1547-2016 2018-09-16T05:56:10Z Radar inference of the bulk properties of glacier beds, most notably identifying basal melting, is, in general, derived from the basal reflection coefficient. On the scale of an ice sheet, unambiguous determination of basal reflection is primarily limited by uncertainty in the englacial attenuation of the radio wave, which is an Arrhenius function of temperature. Existing bed-returned power algorithms for deriving attenuation assume that the attenuation rate is regionally constant, which is not feasible at an ice-sheet-wide scale. Here we introduce a new semi-empirical framework for deriving englacial attenuation, and, to demonstrate its efficacy, we apply it to the Greenland Ice Sheet. A central feature is the use of a prior Arrhenius temperature model to estimate the spatial variation in englacial attenuation as a first guess input for the radar algorithm. We demonstrate regions of solution convergence for two input temperature fields and for independently analysed field campaigns. The coverage achieved is a trade-off with uncertainty and we propose that the algorithm can be “tuned” for discrimination of basal melt (attenuation loss uncertainty ∼ 5 dB). This is supported by our physically realistic (∼ 20 dB) range for the basal reflection coefficient. Finally, we show that the attenuation solution can be used to predict the temperature bias of thermomechanical ice sheet models and is in agreement with known model temperature biases at the Dye 3 ice core. Article in Journal/Newspaper Dye 3 Dye-3 glacier Greenland ice core Ice Sheet Imperial College London: Spiral Greenland The Cryosphere 10 4 1547 1570 |
institution |
Open Polar |
collection |
Imperial College London: Spiral |
op_collection_id |
ftimperialcol |
language |
unknown |
topic |
Meteorology & Atmospheric Sciences 0405 Oceanography 0406 Physical Geography And Environmental Geoscience |
spellingShingle |
Meteorology & Atmospheric Sciences 0405 Oceanography 0406 Physical Geography And Environmental Geoscience Jordan, T Bamber, J Williams, C Paden, J Siegert, MJ Huybrechts, P Gagliardini, O Gillet-Chaulet, F An ice sheet wide framework for radar-inference of englacial attenuation and basal reflection with application to Greenland |
topic_facet |
Meteorology & Atmospheric Sciences 0405 Oceanography 0406 Physical Geography And Environmental Geoscience |
description |
Radar inference of the bulk properties of glacier beds, most notably identifying basal melting, is, in general, derived from the basal reflection coefficient. On the scale of an ice sheet, unambiguous determination of basal reflection is primarily limited by uncertainty in the englacial attenuation of the radio wave, which is an Arrhenius function of temperature. Existing bed-returned power algorithms for deriving attenuation assume that the attenuation rate is regionally constant, which is not feasible at an ice-sheet-wide scale. Here we introduce a new semi-empirical framework for deriving englacial attenuation, and, to demonstrate its efficacy, we apply it to the Greenland Ice Sheet. A central feature is the use of a prior Arrhenius temperature model to estimate the spatial variation in englacial attenuation as a first guess input for the radar algorithm. We demonstrate regions of solution convergence for two input temperature fields and for independently analysed field campaigns. The coverage achieved is a trade-off with uncertainty and we propose that the algorithm can be “tuned” for discrimination of basal melt (attenuation loss uncertainty ∼ 5 dB). This is supported by our physically realistic (∼ 20 dB) range for the basal reflection coefficient. Finally, we show that the attenuation solution can be used to predict the temperature bias of thermomechanical ice sheet models and is in agreement with known model temperature biases at the Dye 3 ice core. |
author2 |
Natural Environment Research Council (NERC) Natural Environment Research Council (NERC) |
format |
Article in Journal/Newspaper |
author |
Jordan, T Bamber, J Williams, C Paden, J Siegert, MJ Huybrechts, P Gagliardini, O Gillet-Chaulet, F |
author_facet |
Jordan, T Bamber, J Williams, C Paden, J Siegert, MJ Huybrechts, P Gagliardini, O Gillet-Chaulet, F |
author_sort |
Jordan, T |
title |
An ice sheet wide framework for radar-inference of englacial attenuation and basal reflection with application to Greenland |
title_short |
An ice sheet wide framework for radar-inference of englacial attenuation and basal reflection with application to Greenland |
title_full |
An ice sheet wide framework for radar-inference of englacial attenuation and basal reflection with application to Greenland |
title_fullStr |
An ice sheet wide framework for radar-inference of englacial attenuation and basal reflection with application to Greenland |
title_full_unstemmed |
An ice sheet wide framework for radar-inference of englacial attenuation and basal reflection with application to Greenland |
title_sort |
ice sheet wide framework for radar-inference of englacial attenuation and basal reflection with application to greenland |
publisher |
European Geosciences Union (EGU) |
publishDate |
2016 |
url |
http://hdl.handle.net/10044/1/37416 https://doi.org/10.5194/tc-10-1547-2016 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Dye 3 Dye-3 glacier Greenland ice core Ice Sheet |
genre_facet |
Dye 3 Dye-3 glacier Greenland ice core Ice Sheet |
op_source |
1570 1547 |
op_relation |
Cryosphere |
op_rights |
© Author(s) 2016. CC Attribution 3.0 License. |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/tc-10-1547-2016 |
container_title |
The Cryosphere |
container_volume |
10 |
container_issue |
4 |
container_start_page |
1547 |
op_container_end_page |
1570 |
_version_ |
1766398724799463424 |