A revised calibration of the interferometric mode of the CryoSat-2 radar altimeter improves ice height and height change measurements in western Greenland
We compare geocoded heights derived from the interferometric mode (SARIn) of CryoSat to surface heights from calibration–validation sites on Devon Ice Cap and western Greenland. Comparisons are included for both the heights derived from the first return (the point-of-closest-approach or POCA) and he...
Published in: | The Cryosphere |
---|---|
Main Authors: | , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
National Snow and Ice Data Center
2017
|
Subjects: | |
Online Access: | http://hdl.handle.net/10852/62741 http://urn.nb.no/URN:NBN:no-65314 https://doi.org/10.5194/tc-11-1041-2017 |
id |
ftoslouniv:oai:www.duo.uio.no:10852/62741 |
---|---|
record_format |
openpolar |
spelling |
ftoslouniv:oai:www.duo.uio.no:10852/62741 2023-05-15T16:26:36+02:00 A revised calibration of the interferometric mode of the CryoSat-2 radar altimeter improves ice height and height change measurements in western Greenland Gray, Laurence Burgess, David Copland, Luke Dunse, Thorben Langley, Kirsty Moholdt, Geir 2017-08-02T10:50:10Z http://hdl.handle.net/10852/62741 http://urn.nb.no/URN:NBN:no-65314 https://doi.org/10.5194/tc-11-1041-2017 EN eng National Snow and Ice Data Center http://urn.nb.no/URN:NBN:no-65314 Gray, Laurence Burgess, David Copland, Luke Dunse, Thorben Langley, Kirsty Moholdt, Geir . A revised calibration of the interferometric mode of the CryoSat-2 radar altimeter improves ice height and height change measurements in western Greenland. The Cryosphere. 2017, 11, 1041-1058 http://hdl.handle.net/10852/62741 1483774 info:ofi/fmt:kev:mtx:ctx&ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=The Cryosphere&rft.volume=11&rft.spage=1041&rft.date=2017 The Cryosphere 11 1041 1058 http://dx.doi.org/10.5194/tc-11-1041-2017 URN:NBN:no-65314 Fulltext https://www.duo.uio.no/bitstream/handle/10852/62741/4/tc-11-1041-2017.pdf Attribution 3.0 Unported https://creativecommons.org/licenses/by/3.0/ CC-BY 1994-0416 Journal article Tidsskriftartikkel Peer reviewed PublishedVersion 2017 ftoslouniv https://doi.org/10.5194/tc-11-1041-2017 2020-06-21T08:51:46Z We compare geocoded heights derived from the interferometric mode (SARIn) of CryoSat to surface heights from calibration–validation sites on Devon Ice Cap and western Greenland. Comparisons are included for both the heights derived from the first return (the point-of-closest-approach or POCA) and heights derived from delayed waveform returns (swath processing). While swath-processed heights are normally less precise than edited POCA heights, e.g. standard deviations of ∼ 3 and ∼ 1.5 m respectively for the western Greenland site, the increased coverage possible with swath data complements the POCA data and provides useful information for both system calibration and improving digital elevation models (DEMs). We show that the pre-launch interferometric baseline coupled with an additional roll correction ( ∼ 0.0075° ± 0.0025°), or equivalent phase correction ( ∼ 0.0435 ± 0.0145 radians), provides an improved calibration of the interferometric SARIn mode. We extend the potential use of SARIn data by showing the influence of surface conditions, especially melt, on the return waveforms and that it is possible to detect and measure the height of summer supraglacial lakes in western Greenland. A supraglacial lake can provide a strong radar target in the waveform, stronger than the initial POCA return, if viewed at near-normal incidence. This provides an ideal situation for swath processing and we demonstrate a height precision of ∼ 0.5 m for two lake sites, one in the accumulation zone and one in the ablation zone, which were measured every year from 2010 or 2011 to 2016. Each year the lake in the ablation zone was viewed in June by ascending passes and then 5.5 days later by descending passes, which allows an approximate estimate of the filling rate. The results suggest that CryoSat waveform data and measurements of supraglacial lake height change could complement the use of optical satellite imagery and be helpful as proxy indicators for surface melt around Greenland. Article in Journal/Newspaper Greenland Ice cap The Cryosphere Universitet i Oslo: Digitale utgivelser ved UiO (DUO) Greenland Devon Ice Cap ENVELOPE(-82.499,-82.499,75.335,75.335) The Cryosphere 11 3 1041 1058 |
institution |
Open Polar |
collection |
Universitet i Oslo: Digitale utgivelser ved UiO (DUO) |
op_collection_id |
ftoslouniv |
language |
English |
description |
We compare geocoded heights derived from the interferometric mode (SARIn) of CryoSat to surface heights from calibration–validation sites on Devon Ice Cap and western Greenland. Comparisons are included for both the heights derived from the first return (the point-of-closest-approach or POCA) and heights derived from delayed waveform returns (swath processing). While swath-processed heights are normally less precise than edited POCA heights, e.g. standard deviations of ∼ 3 and ∼ 1.5 m respectively for the western Greenland site, the increased coverage possible with swath data complements the POCA data and provides useful information for both system calibration and improving digital elevation models (DEMs). We show that the pre-launch interferometric baseline coupled with an additional roll correction ( ∼ 0.0075° ± 0.0025°), or equivalent phase correction ( ∼ 0.0435 ± 0.0145 radians), provides an improved calibration of the interferometric SARIn mode. We extend the potential use of SARIn data by showing the influence of surface conditions, especially melt, on the return waveforms and that it is possible to detect and measure the height of summer supraglacial lakes in western Greenland. A supraglacial lake can provide a strong radar target in the waveform, stronger than the initial POCA return, if viewed at near-normal incidence. This provides an ideal situation for swath processing and we demonstrate a height precision of ∼ 0.5 m for two lake sites, one in the accumulation zone and one in the ablation zone, which were measured every year from 2010 or 2011 to 2016. Each year the lake in the ablation zone was viewed in June by ascending passes and then 5.5 days later by descending passes, which allows an approximate estimate of the filling rate. The results suggest that CryoSat waveform data and measurements of supraglacial lake height change could complement the use of optical satellite imagery and be helpful as proxy indicators for surface melt around Greenland. |
format |
Article in Journal/Newspaper |
author |
Gray, Laurence Burgess, David Copland, Luke Dunse, Thorben Langley, Kirsty Moholdt, Geir |
spellingShingle |
Gray, Laurence Burgess, David Copland, Luke Dunse, Thorben Langley, Kirsty Moholdt, Geir A revised calibration of the interferometric mode of the CryoSat-2 radar altimeter improves ice height and height change measurements in western Greenland |
author_facet |
Gray, Laurence Burgess, David Copland, Luke Dunse, Thorben Langley, Kirsty Moholdt, Geir |
author_sort |
Gray, Laurence |
title |
A revised calibration of the interferometric mode of the CryoSat-2 radar altimeter improves ice height and height change measurements in western Greenland |
title_short |
A revised calibration of the interferometric mode of the CryoSat-2 radar altimeter improves ice height and height change measurements in western Greenland |
title_full |
A revised calibration of the interferometric mode of the CryoSat-2 radar altimeter improves ice height and height change measurements in western Greenland |
title_fullStr |
A revised calibration of the interferometric mode of the CryoSat-2 radar altimeter improves ice height and height change measurements in western Greenland |
title_full_unstemmed |
A revised calibration of the interferometric mode of the CryoSat-2 radar altimeter improves ice height and height change measurements in western Greenland |
title_sort |
revised calibration of the interferometric mode of the cryosat-2 radar altimeter improves ice height and height change measurements in western greenland |
publisher |
National Snow and Ice Data Center |
publishDate |
2017 |
url |
http://hdl.handle.net/10852/62741 http://urn.nb.no/URN:NBN:no-65314 https://doi.org/10.5194/tc-11-1041-2017 |
long_lat |
ENVELOPE(-82.499,-82.499,75.335,75.335) |
geographic |
Greenland Devon Ice Cap |
geographic_facet |
Greenland Devon Ice Cap |
genre |
Greenland Ice cap The Cryosphere |
genre_facet |
Greenland Ice cap The Cryosphere |
op_source |
1994-0416 |
op_relation |
http://urn.nb.no/URN:NBN:no-65314 Gray, Laurence Burgess, David Copland, Luke Dunse, Thorben Langley, Kirsty Moholdt, Geir . A revised calibration of the interferometric mode of the CryoSat-2 radar altimeter improves ice height and height change measurements in western Greenland. The Cryosphere. 2017, 11, 1041-1058 http://hdl.handle.net/10852/62741 1483774 info:ofi/fmt:kev:mtx:ctx&ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=The Cryosphere&rft.volume=11&rft.spage=1041&rft.date=2017 The Cryosphere 11 1041 1058 http://dx.doi.org/10.5194/tc-11-1041-2017 URN:NBN:no-65314 Fulltext https://www.duo.uio.no/bitstream/handle/10852/62741/4/tc-11-1041-2017.pdf |
op_rights |
Attribution 3.0 Unported https://creativecommons.org/licenses/by/3.0/ |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/tc-11-1041-2017 |
container_title |
The Cryosphere |
container_volume |
11 |
container_issue |
3 |
container_start_page |
1041 |
op_container_end_page |
1058 |
_version_ |
1766015541500182528 |