The Antarctic sea ice cover from ICESat-2 and CryoSat-2: freeboard, snow depth, and ice thickness
We offer a view of the Antarctic sea ice cover from lidar (ICESat-2) and radar (CryoSat-2) altimetry, with retrievals of freeboard, snow depth, and ice thickness that span an 8-month winter between 1 April and 16 November 2019. Snow depths are from freeboard differences. The multiyear ice observed i...
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Copernicus Publications
2020
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ftdoajarticles:oai:doaj.org/article:55f0bf8845f542fcaf57ca1ba0ff296e 2023-05-15T13:24:16+02:00 The Antarctic sea ice cover from ICESat-2 and CryoSat-2: freeboard, snow depth, and ice thickness S. Kacimi R. Kwok 2020-12-01T00:00:00Z https://doi.org/10.5194/tc-14-4453-2020 https://doaj.org/article/55f0bf8845f542fcaf57ca1ba0ff296e EN eng Copernicus Publications https://tc.copernicus.org/articles/14/4453/2020/tc-14-4453-2020.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-14-4453-2020 1994-0416 1994-0424 https://doaj.org/article/55f0bf8845f542fcaf57ca1ba0ff296e The Cryosphere, Vol 14, Pp 4453-4474 (2020) Environmental sciences GE1-350 Geology QE1-996.5 article 2020 ftdoajarticles https://doi.org/10.5194/tc-14-4453-2020 2022-12-31T09:38:06Z We offer a view of the Antarctic sea ice cover from lidar (ICESat-2) and radar (CryoSat-2) altimetry, with retrievals of freeboard, snow depth, and ice thickness that span an 8-month winter between 1 April and 16 November 2019. Snow depths are from freeboard differences. The multiyear ice observed in the West Weddell sector is the thickest, with a mean sector thickness > 2 m. The thinnest ice is found near polynyas (Ross Sea and Ronne Ice Shelf) where new ice areas are exported seaward and entrained in the surrounding ice cover. For all months, the results suggest that ∼ 65 %–70 % of the total freeboard is comprised of snow. The remarkable mechanical convergence in coastal Amundsen Sea, associated with onshore winds, was captured by ICESat-2 and CryoSat-2. We observe a corresponding correlated increase in freeboards, snow depth, and ice thickness. While the spatial patterns in the freeboard, snow depth, and thickness composites are as expected, the observed seasonality in these variables is rather weak. This most likely results from competing processes (snowfall, snow redistribution, snow and ice formation, ice deformation, and basal growth and melt) that contribute to uncorrelated changes in the total and radar freeboards. Evidence points to biases in CryoSat-2 estimates of ice freeboard of at least a few centimeters from high salinity snow ( > 10) in the basal layer resulting in lower or higher snow depth and ice thickness retrievals, although the extent of these areas cannot be established in the current data set. Adjusting CryoSat-2 freeboards by 3–6 cm gives a circumpolar ice volume of 17 900–15 600 km 3 in October, for an average thickness of ∼ 1.29–1.13 m. Validation of Antarctic sea ice parameters remains a challenge, as there are no seasonally and regionally diverse data sets that could be used to assess these large-scale satellite retrievals. Article in Journal/Newspaper Amundsen Sea Antarc* Antarctic Ice Shelf Ronne Ice Shelf Ross Sea Sea ice The Cryosphere Directory of Open Access Journals: DOAJ Articles Antarctic The Antarctic Ross Sea Amundsen Sea Weddell Ronne Ice Shelf ENVELOPE(-61.000,-61.000,-78.500,-78.500) The Cryosphere 14 12 4453 4474 |
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 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 S. Kacimi R. Kwok The Antarctic sea ice cover from ICESat-2 and CryoSat-2: freeboard, snow depth, and ice thickness |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
We offer a view of the Antarctic sea ice cover from lidar (ICESat-2) and radar (CryoSat-2) altimetry, with retrievals of freeboard, snow depth, and ice thickness that span an 8-month winter between 1 April and 16 November 2019. Snow depths are from freeboard differences. The multiyear ice observed in the West Weddell sector is the thickest, with a mean sector thickness > 2 m. The thinnest ice is found near polynyas (Ross Sea and Ronne Ice Shelf) where new ice areas are exported seaward and entrained in the surrounding ice cover. For all months, the results suggest that ∼ 65 %–70 % of the total freeboard is comprised of snow. The remarkable mechanical convergence in coastal Amundsen Sea, associated with onshore winds, was captured by ICESat-2 and CryoSat-2. We observe a corresponding correlated increase in freeboards, snow depth, and ice thickness. While the spatial patterns in the freeboard, snow depth, and thickness composites are as expected, the observed seasonality in these variables is rather weak. This most likely results from competing processes (snowfall, snow redistribution, snow and ice formation, ice deformation, and basal growth and melt) that contribute to uncorrelated changes in the total and radar freeboards. Evidence points to biases in CryoSat-2 estimates of ice freeboard of at least a few centimeters from high salinity snow ( > 10) in the basal layer resulting in lower or higher snow depth and ice thickness retrievals, although the extent of these areas cannot be established in the current data set. Adjusting CryoSat-2 freeboards by 3–6 cm gives a circumpolar ice volume of 17 900–15 600 km 3 in October, for an average thickness of ∼ 1.29–1.13 m. Validation of Antarctic sea ice parameters remains a challenge, as there are no seasonally and regionally diverse data sets that could be used to assess these large-scale satellite retrievals. |
format |
Article in Journal/Newspaper |
author |
S. Kacimi R. Kwok |
author_facet |
S. Kacimi R. Kwok |
author_sort |
S. Kacimi |
title |
The Antarctic sea ice cover from ICESat-2 and CryoSat-2: freeboard, snow depth, and ice thickness |
title_short |
The Antarctic sea ice cover from ICESat-2 and CryoSat-2: freeboard, snow depth, and ice thickness |
title_full |
The Antarctic sea ice cover from ICESat-2 and CryoSat-2: freeboard, snow depth, and ice thickness |
title_fullStr |
The Antarctic sea ice cover from ICESat-2 and CryoSat-2: freeboard, snow depth, and ice thickness |
title_full_unstemmed |
The Antarctic sea ice cover from ICESat-2 and CryoSat-2: freeboard, snow depth, and ice thickness |
title_sort |
antarctic sea ice cover from icesat-2 and cryosat-2: freeboard, snow depth, and ice thickness |
publisher |
Copernicus Publications |
publishDate |
2020 |
url |
https://doi.org/10.5194/tc-14-4453-2020 https://doaj.org/article/55f0bf8845f542fcaf57ca1ba0ff296e |
long_lat |
ENVELOPE(-61.000,-61.000,-78.500,-78.500) |
geographic |
Antarctic The Antarctic Ross Sea Amundsen Sea Weddell Ronne Ice Shelf |
geographic_facet |
Antarctic The Antarctic Ross Sea Amundsen Sea Weddell Ronne Ice Shelf |
genre |
Amundsen Sea Antarc* Antarctic Ice Shelf Ronne Ice Shelf Ross Sea Sea ice The Cryosphere |
genre_facet |
Amundsen Sea Antarc* Antarctic Ice Shelf Ronne Ice Shelf Ross Sea Sea ice The Cryosphere |
op_source |
The Cryosphere, Vol 14, Pp 4453-4474 (2020) |
op_relation |
https://tc.copernicus.org/articles/14/4453/2020/tc-14-4453-2020.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-14-4453-2020 1994-0416 1994-0424 https://doaj.org/article/55f0bf8845f542fcaf57ca1ba0ff296e |
op_doi |
https://doi.org/10.5194/tc-14-4453-2020 |
container_title |
The Cryosphere |
container_volume |
14 |
container_issue |
12 |
container_start_page |
4453 |
op_container_end_page |
4474 |
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1766378426291191808 |