Impact of assimilating a merged sea-ice thickness from CryoSat-2 and SMOS in the Arctic reanalysis
<p>Accurately forecasting the sea-ice thickness (SIT) in the Arctic is a major challenge. The new SIT product (referred to as CS2SMOS) merges measurements from the CryoSat-2 and SMOS satellites on a weekly basis during the winter. The impact of assimilating CS2SMOS data is tested for the TOPAZ...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-11-01
|
| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/12/3671/2018/tc-12-3671-2018.pdf |
| _version_ | 1818336566065496064 |
|---|---|
| author | J. Xie F. Counillon F. Counillon L. Bertino L. Bertino |
| author_facet | J. Xie F. Counillon F. Counillon L. Bertino L. Bertino |
| author_sort | J. Xie |
| collection | DOAJ |
| description | <p>Accurately
forecasting the sea-ice thickness (SIT) in the Arctic is a major challenge.
The new SIT product (referred to as CS2SMOS) merges measurements from the
CryoSat-2 and SMOS satellites on a weekly basis during the winter. The impact
of assimilating CS2SMOS data is tested for the TOPAZ4 system – the Arctic
component of the Copernicus Marine Environment Monitoring Services (CMEMS).
TOPAZ4 currently assimilates a large set of ocean and sea-ice observations
with the Deterministic Ensemble Kalman Filter (DEnKF).</p>
<p>Two parallel reanalyses are conducted without (Official run) and with (Test
run) assimilation of CS2SMOS data from 19 March 2014 to 31 March 2015. Since only mapping errors were provided in the CS2SMOS
observation, an arbitrary term was added to compensate for the missing
errors, but was found a posteriori too large. The SIT bias (too thin) is
reduced from 16 to 5 cm and the standard errors decrease from 53 to 38 cm (by 28 %) when compared to the assimilated SIT. When compared to
independent SIT observations, the error reduction is 24 % against the ice
mass balance (IMB) buoy 2013F and by 12.5 % against SIT data from the
IceBridge campaigns. The improvement of sea-ice volume persists through the
summer months in the absence of CS2SMOS data. Comparisons to sea-ice drift
from the satellites show that dynamical adjustments reduce the drift errors
around the North Pole by about 8 %–9 % in December 2014 and February 2015.
Finally, using the degrees of freedom for signal (DFS), we find that CS2SMOS
makes the prime source of information in the central Arctic and in the Kara
Sea. We therefore recommend the assimilation of C2SMOS for Arctic reanalyses
in order to improve the ice thickness and the ice drift.</p> |
| first_indexed | 2024-12-13T14:41:21Z |
| format | Article |
| id | doaj.art-8bcad0478df04622b811a107da106647 |
| institution | Directory Open Access Journal |
| issn | 1994-0416 1994-0424 |
| language | English |
| last_indexed | 2024-12-13T14:41:21Z |
| publishDate | 2018-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The Cryosphere |
| spelling | doaj.art-8bcad0478df04622b811a107da1066472022-12-21T23:41:36ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242018-11-01123671369110.5194/tc-12-3671-2018Impact of assimilating a merged sea-ice thickness from CryoSat-2 and SMOS in the Arctic reanalysisJ. Xie0F. Counillon1F. Counillon2L. Bertino3L. Bertino4Nansen Environmental and Remote Sensing Center, Bergen N5006, NorwayNansen Environmental and Remote Sensing Center, Bergen N5006, NorwayBjerknes Center for Climate Research, Bergen, NorwayNansen Environmental and Remote Sensing Center, Bergen N5006, NorwayBjerknes Center for Climate Research, Bergen, Norway<p>Accurately forecasting the sea-ice thickness (SIT) in the Arctic is a major challenge. The new SIT product (referred to as CS2SMOS) merges measurements from the CryoSat-2 and SMOS satellites on a weekly basis during the winter. The impact of assimilating CS2SMOS data is tested for the TOPAZ4 system – the Arctic component of the Copernicus Marine Environment Monitoring Services (CMEMS). TOPAZ4 currently assimilates a large set of ocean and sea-ice observations with the Deterministic Ensemble Kalman Filter (DEnKF).</p> <p>Two parallel reanalyses are conducted without (Official run) and with (Test run) assimilation of CS2SMOS data from 19 March 2014 to 31 March 2015. Since only mapping errors were provided in the CS2SMOS observation, an arbitrary term was added to compensate for the missing errors, but was found a posteriori too large. The SIT bias (too thin) is reduced from 16 to 5 cm and the standard errors decrease from 53 to 38 cm (by 28 %) when compared to the assimilated SIT. When compared to independent SIT observations, the error reduction is 24 % against the ice mass balance (IMB) buoy 2013F and by 12.5 % against SIT data from the IceBridge campaigns. The improvement of sea-ice volume persists through the summer months in the absence of CS2SMOS data. Comparisons to sea-ice drift from the satellites show that dynamical adjustments reduce the drift errors around the North Pole by about 8 %–9 % in December 2014 and February 2015. Finally, using the degrees of freedom for signal (DFS), we find that CS2SMOS makes the prime source of information in the central Arctic and in the Kara Sea. We therefore recommend the assimilation of C2SMOS for Arctic reanalyses in order to improve the ice thickness and the ice drift.</p>https://www.the-cryosphere.net/12/3671/2018/tc-12-3671-2018.pdf |
| spellingShingle | J. Xie F. Counillon F. Counillon L. Bertino L. Bertino Impact of assimilating a merged sea-ice thickness from CryoSat-2 and SMOS in the Arctic reanalysis The Cryosphere |
| title | Impact of assimilating a merged sea-ice thickness from CryoSat-2 and SMOS in the Arctic reanalysis |
| title_full | Impact of assimilating a merged sea-ice thickness from CryoSat-2 and SMOS in the Arctic reanalysis |
| title_fullStr | Impact of assimilating a merged sea-ice thickness from CryoSat-2 and SMOS in the Arctic reanalysis |
| title_full_unstemmed | Impact of assimilating a merged sea-ice thickness from CryoSat-2 and SMOS in the Arctic reanalysis |
| title_short | Impact of assimilating a merged sea-ice thickness from CryoSat-2 and SMOS in the Arctic reanalysis |
| title_sort | impact of assimilating a merged sea ice thickness from cryosat 2 and smos in the arctic reanalysis |
| url | https://www.the-cryosphere.net/12/3671/2018/tc-12-3671-2018.pdf |
| work_keys_str_mv | AT jxie impactofassimilatingamergedseaicethicknessfromcryosat2andsmosinthearcticreanalysis AT fcounillon impactofassimilatingamergedseaicethicknessfromcryosat2andsmosinthearcticreanalysis AT fcounillon impactofassimilatingamergedseaicethicknessfromcryosat2andsmosinthearcticreanalysis AT lbertino impactofassimilatingamergedseaicethicknessfromcryosat2andsmosinthearcticreanalysis AT lbertino impactofassimilatingamergedseaicethicknessfromcryosat2andsmosinthearcticreanalysis |