Comparison of CryoSat-2 and ENVISAT radar freeboard over Arctic sea ice: toward an improved Envisat freeboard retrieval
Over the past decade, sea-ice freeboard has been monitored with various satellite altimetric missions with the aim of producing long-term time series of ice thickness. While recent studies have demonstrated the capacity of the CryoSat-2 mission (2010–present) to provide accurate freeboard measuremen...
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Copernicus Publications
2017
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00009089 2023-05-15T15:17:12+02:00 Comparison of CryoSat-2 and ENVISAT radar freeboard over Arctic sea ice: toward an improved Envisat freeboard retrieval Guerreiro, Kevin Fleury, Sara Zakharova, Elena Kouraev, Alexei Rémy, Frédérique Maisongrande, Philippe 2017-09 electronic https://doi.org/10.5194/tc-11-2059-2017 https://noa.gwlb.de/receive/cop_mods_00009089 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00009046/tc-11-2059-2017.pdf https://tc.copernicus.org/articles/11/2059/2017/tc-11-2059-2017.pdf eng eng Copernicus Publications The Cryosphere -- ˜Theœ Cryosphere -- http://www.bibliothek.uni-regensburg.de/ezeit/?2393169 -- http://www.the-cryosphere.net/ -- 1994-0424 https://doi.org/10.5194/tc-11-2059-2017 https://noa.gwlb.de/receive/cop_mods_00009089 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00009046/tc-11-2059-2017.pdf https://tc.copernicus.org/articles/11/2059/2017/tc-11-2059-2017.pdf uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2017 ftnonlinearchiv https://doi.org/10.5194/tc-11-2059-2017 2022-02-08T22:57:42Z Over the past decade, sea-ice freeboard has been monitored with various satellite altimetric missions with the aim of producing long-term time series of ice thickness. While recent studies have demonstrated the capacity of the CryoSat-2 mission (2010–present) to provide accurate freeboard measurements, the current estimates obtained with the Envisat mission (2002–2012) still require some large improvements. In this study, we first estimate Envisat and CryoSat-2 radar freeboard by using the exact same processing algorithms. We then analyse the freeboard difference between the two estimates over the common winter periods (November 2010–April 2011 and November 2011–March 2012). The analysis of along-track data and gridded radar freeboard in conjunction with Envisat pulse-peakiness (PP) maps suggests that the discrepancy between the two sensors is related to the surface properties of sea-ice floes and to the use of a threshold retracker. Based on the relation between the Envisat pulse peakiness and the radar freeboard difference between Envisat and CryoSat-2, we produce a monthly CryoSat-2-like version of Envisat freeboard. The improved Envisat data set freeboard displays a similar spatial distribution to CryoSat-2 (RMSD = 1.5 cm) during the two ice growth seasons and for all months of the period of study. The comparison of the altimetric data sets with in situ ice draught measurements during the common flight period shows that the improved Envisat data set (RMSE = 12–28 cm) is as accurate as CryoSat-2 (RMSE = 15–21 cm) and much more accurate than the uncorrected Envisat data set (RMSE = 178–179 cm). The comparison of the improved Envisat radar freeboard data set is then extended to the rest of the Envisat mission to demonstrate the validity of PP correction from the calibration period. The good agreement between the improved Envisat data set and the in situ ice draught data set (RMSE = 13–32 cm) demonstrates the potential of the PP correction to produce accurate freeboard estimates over the entire Envisat mission lifetime. Article in Journal/Newspaper Arctic Sea ice The Cryosphere Niedersächsisches Online-Archiv NOA Arctic The Cryosphere 11 5 2059 2073 |
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Open Polar |
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Niedersächsisches Online-Archiv NOA |
op_collection_id |
ftnonlinearchiv |
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English |
topic |
article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Guerreiro, Kevin Fleury, Sara Zakharova, Elena Kouraev, Alexei Rémy, Frédérique Maisongrande, Philippe Comparison of CryoSat-2 and ENVISAT radar freeboard over Arctic sea ice: toward an improved Envisat freeboard retrieval |
topic_facet |
article Verlagsveröffentlichung |
description |
Over the past decade, sea-ice freeboard has been monitored with various satellite altimetric missions with the aim of producing long-term time series of ice thickness. While recent studies have demonstrated the capacity of the CryoSat-2 mission (2010–present) to provide accurate freeboard measurements, the current estimates obtained with the Envisat mission (2002–2012) still require some large improvements. In this study, we first estimate Envisat and CryoSat-2 radar freeboard by using the exact same processing algorithms. We then analyse the freeboard difference between the two estimates over the common winter periods (November 2010–April 2011 and November 2011–March 2012). The analysis of along-track data and gridded radar freeboard in conjunction with Envisat pulse-peakiness (PP) maps suggests that the discrepancy between the two sensors is related to the surface properties of sea-ice floes and to the use of a threshold retracker. Based on the relation between the Envisat pulse peakiness and the radar freeboard difference between Envisat and CryoSat-2, we produce a monthly CryoSat-2-like version of Envisat freeboard. The improved Envisat data set freeboard displays a similar spatial distribution to CryoSat-2 (RMSD = 1.5 cm) during the two ice growth seasons and for all months of the period of study. The comparison of the altimetric data sets with in situ ice draught measurements during the common flight period shows that the improved Envisat data set (RMSE = 12–28 cm) is as accurate as CryoSat-2 (RMSE = 15–21 cm) and much more accurate than the uncorrected Envisat data set (RMSE = 178–179 cm). The comparison of the improved Envisat radar freeboard data set is then extended to the rest of the Envisat mission to demonstrate the validity of PP correction from the calibration period. The good agreement between the improved Envisat data set and the in situ ice draught data set (RMSE = 13–32 cm) demonstrates the potential of the PP correction to produce accurate freeboard estimates over the entire Envisat mission lifetime. |
format |
Article in Journal/Newspaper |
author |
Guerreiro, Kevin Fleury, Sara Zakharova, Elena Kouraev, Alexei Rémy, Frédérique Maisongrande, Philippe |
author_facet |
Guerreiro, Kevin Fleury, Sara Zakharova, Elena Kouraev, Alexei Rémy, Frédérique Maisongrande, Philippe |
author_sort |
Guerreiro, Kevin |
title |
Comparison of CryoSat-2 and ENVISAT radar freeboard over Arctic sea ice: toward an improved Envisat freeboard retrieval |
title_short |
Comparison of CryoSat-2 and ENVISAT radar freeboard over Arctic sea ice: toward an improved Envisat freeboard retrieval |
title_full |
Comparison of CryoSat-2 and ENVISAT radar freeboard over Arctic sea ice: toward an improved Envisat freeboard retrieval |
title_fullStr |
Comparison of CryoSat-2 and ENVISAT radar freeboard over Arctic sea ice: toward an improved Envisat freeboard retrieval |
title_full_unstemmed |
Comparison of CryoSat-2 and ENVISAT radar freeboard over Arctic sea ice: toward an improved Envisat freeboard retrieval |
title_sort |
comparison of cryosat-2 and envisat radar freeboard over arctic sea ice: toward an improved envisat freeboard retrieval |
publisher |
Copernicus Publications |
publishDate |
2017 |
url |
https://doi.org/10.5194/tc-11-2059-2017 https://noa.gwlb.de/receive/cop_mods_00009089 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00009046/tc-11-2059-2017.pdf https://tc.copernicus.org/articles/11/2059/2017/tc-11-2059-2017.pdf |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Sea ice The Cryosphere |
genre_facet |
Arctic Sea ice The Cryosphere |
op_relation |
The Cryosphere -- ˜Theœ Cryosphere -- http://www.bibliothek.uni-regensburg.de/ezeit/?2393169 -- http://www.the-cryosphere.net/ -- 1994-0424 https://doi.org/10.5194/tc-11-2059-2017 https://noa.gwlb.de/receive/cop_mods_00009089 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00009046/tc-11-2059-2017.pdf https://tc.copernicus.org/articles/11/2059/2017/tc-11-2059-2017.pdf |
op_rights |
uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/tc-11-2059-2017 |
container_title |
The Cryosphere |
container_volume |
11 |
container_issue |
5 |
container_start_page |
2059 |
op_container_end_page |
2073 |
_version_ |
1766347468925042688 |