A new state-dependent parameterization for the free drift of sea ice
Free-drift estimates of sea ice motion are necessary to produce a seamless observational record combining buoy and satellite-derived sea ice motion vectors. We develop a new parameterization for the free drift of sea ice based on wind forcing, wind turning angle, sea ice state variables (thickness a...
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2022
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ftdoajarticles:oai:doaj.org/article:7f57cb8a16f840be8c59c77bb7dd0298 2023-05-15T18:16:48+02:00 A new state-dependent parameterization for the free drift of sea ice C. Brunette L. B. Tremblay R. Newton 2022-02-01T00:00:00Z https://doi.org/10.5194/tc-16-533-2022 https://doaj.org/article/7f57cb8a16f840be8c59c77bb7dd0298 EN eng Copernicus Publications https://tc.copernicus.org/articles/16/533/2022/tc-16-533-2022.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-16-533-2022 1994-0416 1994-0424 https://doaj.org/article/7f57cb8a16f840be8c59c77bb7dd0298 The Cryosphere, Vol 16, Pp 533-557 (2022) Environmental sciences GE1-350 Geology QE1-996.5 article 2022 ftdoajarticles https://doi.org/10.5194/tc-16-533-2022 2022-12-31T15:09:33Z Free-drift estimates of sea ice motion are necessary to produce a seamless observational record combining buoy and satellite-derived sea ice motion vectors. We develop a new parameterization for the free drift of sea ice based on wind forcing, wind turning angle, sea ice state variables (thickness and concentration), and estimates of the ocean currents. Given the fact that the spatial distribution of the wind–ice–ocean transfer coefficient has a similar structure to that of the spatial distribution of sea ice thickness, we take the standard free-drift equation and introduce a wind–ice–ocean transfer coefficient that scales linearly with ice thickness. Results show a mean bias error of −0.5 cm s −1 (low-speed bias) and a root-mean-square error of 5.1 cm s −1 , considering daily buoy drift data as truth. This represents a 35 % reduction of the error on drift speed compared to the free-drift estimates used in the Polar Pathfinder dataset ( Tschudi et al. , 2019 b ) . The thickness-dependent transfer coefficient provides an improved seasonality and long-term trend of the sea ice drift speed, with a minimum (maximum) drift speed in May (October), compared to July (January) for the constant transfer coefficient parameterizations which simply follow the peak in mean surface wind stresses. Over the 1979–2019 period, the trend in sea ice drift in this new model is +0.45 cm s −1 per decade compared with +0.39 cm s −1 per decade from the buoy observations, whereas there is essentially no trend in a free-drift parameterization with a constant transfer coefficient ( −0.09 cm s −1 per decade) or the Polar Pathfinder free-drift input data ( −0.01 cm s −1 per decade). The optimal wind turning angle obtained from a least-squares fitting is 25 ∘ , resulting in a mean error and a root-mean-square error of +3 and 42 ∘ on the direction of the drift, respectively. The ocean current estimates obtained from the minimization procedure resolve key large-scale features such as the Beaufort Gyre and Transpolar Drift Stream and are in good ... Article in Journal/Newspaper Sea ice The Cryosphere Directory of Open Access Journals: DOAJ Articles The Cryosphere 16 2 533 557 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
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ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 C. Brunette L. B. Tremblay R. Newton A new state-dependent parameterization for the free drift of sea ice |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
Free-drift estimates of sea ice motion are necessary to produce a seamless observational record combining buoy and satellite-derived sea ice motion vectors. We develop a new parameterization for the free drift of sea ice based on wind forcing, wind turning angle, sea ice state variables (thickness and concentration), and estimates of the ocean currents. Given the fact that the spatial distribution of the wind–ice–ocean transfer coefficient has a similar structure to that of the spatial distribution of sea ice thickness, we take the standard free-drift equation and introduce a wind–ice–ocean transfer coefficient that scales linearly with ice thickness. Results show a mean bias error of −0.5 cm s −1 (low-speed bias) and a root-mean-square error of 5.1 cm s −1 , considering daily buoy drift data as truth. This represents a 35 % reduction of the error on drift speed compared to the free-drift estimates used in the Polar Pathfinder dataset ( Tschudi et al. , 2019 b ) . The thickness-dependent transfer coefficient provides an improved seasonality and long-term trend of the sea ice drift speed, with a minimum (maximum) drift speed in May (October), compared to July (January) for the constant transfer coefficient parameterizations which simply follow the peak in mean surface wind stresses. Over the 1979–2019 period, the trend in sea ice drift in this new model is +0.45 cm s −1 per decade compared with +0.39 cm s −1 per decade from the buoy observations, whereas there is essentially no trend in a free-drift parameterization with a constant transfer coefficient ( −0.09 cm s −1 per decade) or the Polar Pathfinder free-drift input data ( −0.01 cm s −1 per decade). The optimal wind turning angle obtained from a least-squares fitting is 25 ∘ , resulting in a mean error and a root-mean-square error of +3 and 42 ∘ on the direction of the drift, respectively. The ocean current estimates obtained from the minimization procedure resolve key large-scale features such as the Beaufort Gyre and Transpolar Drift Stream and are in good ... |
format |
Article in Journal/Newspaper |
author |
C. Brunette L. B. Tremblay R. Newton |
author_facet |
C. Brunette L. B. Tremblay R. Newton |
author_sort |
C. Brunette |
title |
A new state-dependent parameterization for the free drift of sea ice |
title_short |
A new state-dependent parameterization for the free drift of sea ice |
title_full |
A new state-dependent parameterization for the free drift of sea ice |
title_fullStr |
A new state-dependent parameterization for the free drift of sea ice |
title_full_unstemmed |
A new state-dependent parameterization for the free drift of sea ice |
title_sort |
new state-dependent parameterization for the free drift of sea ice |
publisher |
Copernicus Publications |
publishDate |
2022 |
url |
https://doi.org/10.5194/tc-16-533-2022 https://doaj.org/article/7f57cb8a16f840be8c59c77bb7dd0298 |
genre |
Sea ice The Cryosphere |
genre_facet |
Sea ice The Cryosphere |
op_source |
The Cryosphere, Vol 16, Pp 533-557 (2022) |
op_relation |
https://tc.copernicus.org/articles/16/533/2022/tc-16-533-2022.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-16-533-2022 1994-0416 1994-0424 https://doaj.org/article/7f57cb8a16f840be8c59c77bb7dd0298 |
op_doi |
https://doi.org/10.5194/tc-16-533-2022 |
container_title |
The Cryosphere |
container_volume |
16 |
container_issue |
2 |
container_start_page |
533 |
op_container_end_page |
557 |
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1766190688602423296 |