Refining the sea surface identification approach for determining freeboards in the ICESat-2 sea ice products
In Release 001 and 002 of the ICESat-2 sea ice products, candidate height segments used to estimate the reference sea surface height for freeboard calculations included two surface types: specular and smooth dark leads. We found that the uncorrected photon rates, used as proxies of surface reflectan...
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ftdoajarticles:oai:doaj.org/article:2035509ee9e04bc793cf11e70295b159 2023-05-15T15:06:18+02:00 Refining the sea surface identification approach for determining freeboards in the ICESat-2 sea ice products R. Kwok A. A. Petty M. Bagnardi N. T. Kurtz G. F. Cunningham A. Ivanoff S. Kacimi 2021-02-01T00:00:00Z https://doi.org/10.5194/tc-15-821-2021 https://doaj.org/article/2035509ee9e04bc793cf11e70295b159 EN eng Copernicus Publications https://tc.copernicus.org/articles/15/821/2021/tc-15-821-2021.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-15-821-2021 1994-0416 1994-0424 https://doaj.org/article/2035509ee9e04bc793cf11e70295b159 The Cryosphere, Vol 15, Pp 821-833 (2021) Environmental sciences GE1-350 Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.5194/tc-15-821-2021 2022-12-31T12:06:31Z In Release 001 and 002 of the ICESat-2 sea ice products, candidate height segments used to estimate the reference sea surface height for freeboard calculations included two surface types: specular and smooth dark leads. We found that the uncorrected photon rates, used as proxies of surface reflectance, are attenuated due to clouds resulting in the potential misclassification of sea ice as dark leads, biasing the reference sea surface height relative to those derived from the more reliable specular returns. This results in higher reference sea surface heights and lower estimated ice freeboards. The resolution of available cloud flags from the ICESat-2 atmosphere data product is too coarse to provide useful filtering at the lead segment scale. In Release 003, we have modified the surface-reference-finding algorithm so that only specular leads are used. The consequence of this change can be seen in the composites of mean freeboard of the Arctic and Southern oceans. Broadly, coverages have decreased by ∼10 –20 % because there are fewer leads (by excluding the dark leads), and the composite means have increased by 0–4 cm because of the use of more consistent specular leads. Article in Journal/Newspaper Arctic Sea ice The Cryosphere Directory of Open Access Journals: DOAJ Articles Arctic The Cryosphere 15 2 821 833 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
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Environmental sciences GE1-350 Geology QE1-996.5 R. Kwok A. A. Petty M. Bagnardi N. T. Kurtz G. F. Cunningham A. Ivanoff S. Kacimi Refining the sea surface identification approach for determining freeboards in the ICESat-2 sea ice products |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
In Release 001 and 002 of the ICESat-2 sea ice products, candidate height segments used to estimate the reference sea surface height for freeboard calculations included two surface types: specular and smooth dark leads. We found that the uncorrected photon rates, used as proxies of surface reflectance, are attenuated due to clouds resulting in the potential misclassification of sea ice as dark leads, biasing the reference sea surface height relative to those derived from the more reliable specular returns. This results in higher reference sea surface heights and lower estimated ice freeboards. The resolution of available cloud flags from the ICESat-2 atmosphere data product is too coarse to provide useful filtering at the lead segment scale. In Release 003, we have modified the surface-reference-finding algorithm so that only specular leads are used. The consequence of this change can be seen in the composites of mean freeboard of the Arctic and Southern oceans. Broadly, coverages have decreased by ∼10 –20 % because there are fewer leads (by excluding the dark leads), and the composite means have increased by 0–4 cm because of the use of more consistent specular leads. |
format |
Article in Journal/Newspaper |
author |
R. Kwok A. A. Petty M. Bagnardi N. T. Kurtz G. F. Cunningham A. Ivanoff S. Kacimi |
author_facet |
R. Kwok A. A. Petty M. Bagnardi N. T. Kurtz G. F. Cunningham A. Ivanoff S. Kacimi |
author_sort |
R. Kwok |
title |
Refining the sea surface identification approach for determining freeboards in the ICESat-2 sea ice products |
title_short |
Refining the sea surface identification approach for determining freeboards in the ICESat-2 sea ice products |
title_full |
Refining the sea surface identification approach for determining freeboards in the ICESat-2 sea ice products |
title_fullStr |
Refining the sea surface identification approach for determining freeboards in the ICESat-2 sea ice products |
title_full_unstemmed |
Refining the sea surface identification approach for determining freeboards in the ICESat-2 sea ice products |
title_sort |
refining the sea surface identification approach for determining freeboards in the icesat-2 sea ice products |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-15-821-2021 https://doaj.org/article/2035509ee9e04bc793cf11e70295b159 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Sea ice The Cryosphere |
genre_facet |
Arctic Sea ice The Cryosphere |
op_source |
The Cryosphere, Vol 15, Pp 821-833 (2021) |
op_relation |
https://tc.copernicus.org/articles/15/821/2021/tc-15-821-2021.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-15-821-2021 1994-0416 1994-0424 https://doaj.org/article/2035509ee9e04bc793cf11e70295b159 |
op_doi |
https://doi.org/10.5194/tc-15-821-2021 |
container_title |
The Cryosphere |
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15 |
container_issue |
2 |
container_start_page |
821 |
op_container_end_page |
833 |
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1766337934091354112 |