Three years of sea ice freeboard, snow depth, and ice thickness of the Weddell Sea from Operation IceBridge and CryoSat-2
<p>We examine the variability of sea ice freeboard, snow depth, and ice thickness in three years (2011, 2014, and 2016) of repeat surveys of an IceBridge (OIB) transect across the Weddell Sea. Averaged over this transect, ice thickness ranges from 2.40±1.07 (2011) to 2.60±1.15 m...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-08-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/12/2789/2018/tc-12-2789-2018.pdf |
| _version_ | 1819260185522208768 |
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| author | R. Kwok S. Kacimi |
| author_facet | R. Kwok S. Kacimi |
| author_sort | R. Kwok |
| collection | DOAJ |
| description | <p>We examine the variability of sea ice freeboard, snow
depth, and ice thickness in three years (2011, 2014, and 2016) of repeat
surveys of an IceBridge (OIB) transect across the Weddell Sea. Averaged over
this transect, ice thickness ranges from 2.40±1.07 (2011) to
2.60±1.15 m (2014) and snow depth from 35.8±11.5 (2016) to
43.6±10.2 cm (2014), suggesting a highly variable but broadly thicker
ice cover compared to that inferred from drilling and ship-based
measurements. Spatially, snow depth and ice thickness are higher in the more
deformed ice of the western Weddell. The impact of undersampling the thin
end of the snow depth distribution on the regional statistics, due to the
resolution of the snow radar, is assessed.</p><p>Radar freeboards (uncompensated
for snow thickness) from CryoSat-2 (CS-2) sampled along the same transect
are consistently higher (by up to 8 cm) than those computed using OIB data.
This suggests radar scattering that originates above the snow–ice interface,
possibly due to salinity in the basal layer of the snow column.
Consequently, sea ice thicknesses computed using snow depth estimates solely
from differencing OIB and CS-2 freeboards (without snow radar) are therefore
generally higher; mean differences in sea ice thickness along a transect are
up to ∼ 0.6 m higher (in 2014). This analysis is relevant to
the use of differences between ICESat-2 and CS-2 freeboards to estimate snow
depth for ice thickness calculations. Our analysis also suggests that, even
with these expected biases, this is an improvement over the assumption that
snow depth is equal to the total freeboard, with which the underestimation of
thickness could be up to a meter. Importantly, better characterization of
the source of these biases is critical for obtaining improved estimates and
understanding the limits of retrievals of Weddell Sea ice thickness from
satellite altimeters.</p> |
| first_indexed | 2024-12-23T19:21:53Z |
| format | Article |
| id | doaj.art-7c4c41b6ddb140cbbb41c14702f92ebf |
| institution | Directory Open Access Journal |
| issn | 1994-0416 1994-0424 |
| language | English |
| last_indexed | 2024-12-23T19:21:53Z |
| publishDate | 2018-08-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The Cryosphere |
| spelling | doaj.art-7c4c41b6ddb140cbbb41c14702f92ebf2022-12-21T17:34:09ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242018-08-01122789280110.5194/tc-12-2789-2018Three years of sea ice freeboard, snow depth, and ice thickness of the Weddell Sea from Operation IceBridge and CryoSat-2R. Kwok0S. Kacimi1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USAJet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA<p>We examine the variability of sea ice freeboard, snow depth, and ice thickness in three years (2011, 2014, and 2016) of repeat surveys of an IceBridge (OIB) transect across the Weddell Sea. Averaged over this transect, ice thickness ranges from 2.40±1.07 (2011) to 2.60±1.15 m (2014) and snow depth from 35.8±11.5 (2016) to 43.6±10.2 cm (2014), suggesting a highly variable but broadly thicker ice cover compared to that inferred from drilling and ship-based measurements. Spatially, snow depth and ice thickness are higher in the more deformed ice of the western Weddell. The impact of undersampling the thin end of the snow depth distribution on the regional statistics, due to the resolution of the snow radar, is assessed.</p><p>Radar freeboards (uncompensated for snow thickness) from CryoSat-2 (CS-2) sampled along the same transect are consistently higher (by up to 8 cm) than those computed using OIB data. This suggests radar scattering that originates above the snow–ice interface, possibly due to salinity in the basal layer of the snow column. Consequently, sea ice thicknesses computed using snow depth estimates solely from differencing OIB and CS-2 freeboards (without snow radar) are therefore generally higher; mean differences in sea ice thickness along a transect are up to ∼ 0.6 m higher (in 2014). This analysis is relevant to the use of differences between ICESat-2 and CS-2 freeboards to estimate snow depth for ice thickness calculations. Our analysis also suggests that, even with these expected biases, this is an improvement over the assumption that snow depth is equal to the total freeboard, with which the underestimation of thickness could be up to a meter. Importantly, better characterization of the source of these biases is critical for obtaining improved estimates and understanding the limits of retrievals of Weddell Sea ice thickness from satellite altimeters.</p>https://www.the-cryosphere.net/12/2789/2018/tc-12-2789-2018.pdf |
| spellingShingle | R. Kwok S. Kacimi Three years of sea ice freeboard, snow depth, and ice thickness of the Weddell Sea from Operation IceBridge and CryoSat-2 The Cryosphere |
| title | Three years of sea ice freeboard, snow depth, and ice thickness of the Weddell Sea from Operation IceBridge and CryoSat-2 |
| title_full | Three years of sea ice freeboard, snow depth, and ice thickness of the Weddell Sea from Operation IceBridge and CryoSat-2 |
| title_fullStr | Three years of sea ice freeboard, snow depth, and ice thickness of the Weddell Sea from Operation IceBridge and CryoSat-2 |
| title_full_unstemmed | Three years of sea ice freeboard, snow depth, and ice thickness of the Weddell Sea from Operation IceBridge and CryoSat-2 |
| title_short | Three years of sea ice freeboard, snow depth, and ice thickness of the Weddell Sea from Operation IceBridge and CryoSat-2 |
| title_sort | three years of sea ice freeboard snow depth and ice thickness of the weddell sea from operation icebridge and cryosat 2 |
| url | https://www.the-cryosphere.net/12/2789/2018/tc-12-2789-2018.pdf |
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